The following information will assist the technician in diagnosing body control module (BCM) problems. The technician may view the displays while the vehicle is being driven.

The data messages on the scan tool are divided into the following items:

Module Information

The module information contains the following information:

Powertrain Control Module (PCM) to the BCM A/C Clutch Data

This contains the data sent to the BCM from the powertrain control module (PCM).

Data

Data contains general information regarding the following items:

Inputs

Inputs contain general information regarding the following items:

Outputs

Outputs contain general information regarding the following items:

Module Information: Last 4 Digits of the GM Part Number - Range 00004000-00005999

This number refers to the last 4 digits of the assigned GM Part Number of the BCM Module in the vehicle.

Year Body Control Module Built - Range 1997-1999

This number refers to the model year of the BCM in the vehicle at the time of build.

Body Control Module Option Configuration Number - Range 20000000-30000000

The BCM uses this number in order to identifying the option content currently in the car.

PCM to the BCM A/C Clutch Data

No data received.

A/C Clutch Mode - Range Clutch Enab. Reg/A/C Reg. Off/Off, Low Voltage/ Off, High Temperature/Off, High Pressure/Off, Low Ambient/Off, Low RPM

The message displayed refers to the class 2 serial data communication message from the PCM to the BCM. This message monitors the current state of the A/C compressor clutch. The PCM performs the following functions:

The BCM performs the following functions:

The Clutch Enab. Req (Clutch Enable Requested) display indicates that the PCM is driving the A/C clutch. The A/C Req Off (A/C Requested Off) display indicates that the PCM is not driving the A/C clutch.

The Off, Low Voltage display indicates that the PCM is not driving the A/C clutch because of low battery voltage: 10 volts or less.

The Off, High temperature display indicates that the PCM is not driving the A/C clutch because of high engine coolant temperature: above 121°C (250°F).

The Off, High Pressure display indicates that the PCM is not driving the A/C clutch because of high A/C compressor outlet pressure: above 2928 kPa (424 psi).

The Off, Low Ambient indicates that the PCM is not driving the A/C clutch because of low ambient pressure: below 227 kPa (33 psi).

The Off, Low RPM display indicates that the PCM is not driving the A/C clutch because of low engine RPM: 4 cylinder at below 465 RPM, 6 cylinder at below 440 RPM).

Fuel Sender - Range 0-275 Ohms

The BCM monitors the fuel level sensor value in ohms. The fuel level sensor performs the following functions:

The instrument cluster drives the fuel gauge pointer. Refer to the following table for the fuel sender ohm value to the fuel gauge (pointer) position ratio:

Fuel Sender	Fuel Gauge Position
270 -240 ohms	Full
174 ohms	3/4 Full
140 ohms	Half Full
101 ohms	1/4 Full
40-54 ohms	Empty

Battery Voltage - Range 0-25.5 Volts

This data refers to the battery system voltage that is measured by the BCM.

Ambient Light Sensor Voltage - Range 0-2.6 Volts

The ambient light sensor performs the following functions:

The BCM uses this information in the operation of the ALC and the daytime running lights (DRL).

The BCM supplies 5 volts to the ambient light sensor. The ambient light sensor's internal resistance changes with different levels of ambient light. In high ambient (bright) light, the resistance is low. In the low ambient (dark) light, the resistance is high.

When the sensor is exposed to high ambient light (low resistance) the BCM monitors a high voltage (1.5-2.6 volts) that is interpreted as LIGHT. As the sensor is exposed to low ambient light the internal resistance increases. The BCM will interpret the lower voltage (0-9 volts) as DARK when the voltage signal decreases.

Low Beam Input - Range 0-16 Volts

The BCM uses this input in order to determine the state of the low beam headlamps. A single wire input into the BCM monitors the low beam lamp voltage. On a known good vehicle, with the low beams off, the scan tool displayed value should be battery system voltage.

On a known good vehicle, with the DRL on, the scan tool display value should be 25-83% of battery system voltage.

On a known good vehicle, with the low beams on, the scan tool display value should be 0-16% of the battery system voltage.

On a known good vehicle, with the high beams on (low beams off), the scan tool display value should be the battery system voltage.

High Beam Input - Range 0-16 Volts

The BCM uses this input in order to determine the state of the high beam headlamps. A single wire input monitors the high beam lamp voltage.

On a known good vehicle, with the high beams off, the scan tool displayed value should be battery system voltage. Refer to Battery Voltage.

On a known good vehicle, with the high beams on, the scan tool display value should be 0-16% of the battery system voltage.

Ignition 0 Input - Value Active/Inactive

The BCM uses this input in order to determine the state of the ignition switch. Active is displayed when the ignition switch is in one of the following positions:

Inactive is displayed in any other ignition switch position.

Ignition 1 Input - Value Active/Inactive

The BCM uses this input in order to determine the state of the ignition switch. Active is displayed when the ignition switch is in one of the following positions:

Inactive is displayed in any other ignition switch position.

Ignition 3 Input - Value Active/Inactive

The BCM uses this input in order to determine the state of the ignition switch. Active is displayed when the ignition switch is in the RUN position.

Inactive is displayed in any other ignition switch position.

A/C Request - Value Yes/No

The BCM uses this input in determining whether air conditioning (A/C) is being requested from the HVAC selector. This input is sent out over the class 2 serial data line to the following locations:

YES is displayed when the A/C is being requested.

NO is displayed when the A/C is not being requested.

Note that A/C being requested does not mean that the A/C clutch is engaged. Other variables must be met for the BCM and the PCM to engage the compressor clutch.

Park Lamp Input - Value Active/Inactive

The BCM uses this input in order to determine the state of the parklamps. When the parklamps are illuminated, Active is displayed. When the parklamps are not illuminated, Inactive is displayed.

Turn Signal Switch - Value Active/Inactive

The BCM uses this input in order to determine the state of the turn signals. A 12-volt input from the turn signal circuit is used in order to sense that the turn signals are on. When the turn signals are on or cycling, Active is displayed. When the turn signals are off, Inactive is displayed.

Key in Ignition - Value Yes/No

The BCM uses this input in order to determine whether a key is inserted in the ignition switch. When a key is inserted in the ignition switch (in any position), Yes is displayed. When a key is not inserted (completely removed) in the ignition switch, No is displayed.

Park Brake Switch - Value Yes/No

The BCM uses this input in order to determine whether the parking brake is engaged. The input is received by the BCM and is sent out on the serial peripheral interface (SPI) to the instrument cluster in order to light the brake indicator.

The BCM also sends information out on the class 2 serial data line for use by other modules. When the parking brake is engaged, Yes is displayed. When the parking brake is not engaged, Off is displayed.

Washer Fluid Level - Value OK/Low

The BCM uses this input in order to determine the washer fluid level. The input is received by the BCM and is sent out on the SPI to the instrument cluster in order to light the low washer indicator. When the washer fluid level is above one third full, OK is displayed. When the washer fluid level is less than one third full, Low is displayed.

Low Coolant Level - Value Yes/No

The BCM uses this input in order to determine the engine coolant level. The input is received by the BCM and is sent out on the SPI to the instrument cluster in order to light the low coolant symbol indicator. When the coolant level is low, On is displayed. When the coolant level is not low, Off is displayed.

Driver Door Ajar Switch - Value Yes/No

The BCM uses this input in order to determine the whether the driver door is opened or closed. The input is received by the BCM and is used to power-up the BCM from a low power mode. This condition must be detected when the ignition ON power is inactive (Off).

The BCM also sends the information out on the SPI to the instrument cluster in order to light the instrument cluster and light the door ajar symbol indicator. When the door is open, On is displayed. When the door is closed, Off is displayed.

Passenger Door Ajar Switch - Value Yes/No

The BCM uses this input in order to determine the state of the front passenger door and both rear doors. When either the front passenger or rear door is open, On is displayed. When the front passenger and both rear doors are closed, Off is displayed.

Front Fog Lamp Switch - Value Yes/No

The BCM uses this input in order to determine whether the fog lamps have been requested. When the fog lamp switch is pressed once, the fog lamps will be illuminated providing that the following conditions exist:

1. The ignition 1 is active. (The ignition switch is in the RUN or CRANK position.)
2. The low beams and/or park lamps are ON.
3. The high beam headlights are OFF.

Pressing the fog lamp switch a second time turns off the fog lamps. When the fog lamp switch is pressed once, ON is displayed. When the fog lamp switch is pressed a second time, OFF is displayed. When the high beam headlights are on, the fog lamps will be off. When this occurs, the fog lamp switch display will remain ON until the fog lamp switch is pressed a second time.

Ambient Light Sensor - Value Light/Dark

The BCM uses this input in order to determine whether the ambient light level is light or dark. The BCM uses this information in the operation of the ALC and the DRL features.

When the BCM considers the ambient light to be light, Light is displayed. When the BCM considers the ambient light to be dark, Dark is displayed.

Low Beam/DRL Feedback - Value Low Beam/DRL ON or Low Beam/DRL OFF

The BCM uses this input in order to determine the state of the low beam headlamps. A single wire input into the BCM monitors the low beam lamp voltage. The low beam/DRL ON is displayed when either the low beam or DRL lights are illuminated. When both the low beam and DRL illumination are OFF, low beam/DRL OFF is displayed.

High Beam Feedback - Value High Beams ON/High Beams OFF

The BCM uses this input in order to determine the state of the high beam headlamps. A single wire input into the BCM monitors the high beam headlamp voltage. When the high beams are illuminated, the display will show high beams ON. When the high beams are not illuminated, the display will show high beams OFF.

Passlock® Data - Value Valid/Invalid

Refer to the Vehicle Theft System regarding information about the Passlock® system.

Seatbelt - Value Buckled/Unbuckled

The BCM uses this input in order to determine the state of the drivers seatbelt buckled. When the seatbelt is fastened, the drivers seatbelt buckled will be displayed. When the seatbelt is not fastened, the drivers seatbelt unbuckled will be displayed.

Interior Lamp Output - Value On/Off

This output displays the state of the BCM in commanding the interior lamps (or courtesy lamps). When the BCM is commanding the interior lamps to be illuminated, ON will be displayed. When the BCM is commanding the interior lamps not to be illuminated, OFF will be displayed. The interior lights are commanded ON, under the following conditions:

When the interior lights are to be turned OFF, because a customer is leaving the vehicle (ignition switch in the OFF position for more than 2 minutes). First, the interior lights are to be dimmed, and held that way for a short period of time. Theatre dim the interior lights to the OFF state.

Front Fog Lamp Relay - Value ON/OFF

This output displays the state of the BCM and controls the ground path for the fog lamp relay coil. This output turns the fog lamps ON or OFF.

When the BCM is grounding the fog lamp relay and commanding the front fog lamps to be illuminated, ON is displayed. When the BCM is opening the ground to the fog lamp relay and commanding the front fog lamps not to be illuminated, OFF is displayed.

DRL Relay - Value Active/Inactive

This output displays the state of the BCM in controlling the ground path for the DRL relay coil, turning the DRL illumination ON or OFF.

When the BCM is grounding the DRL relay coil and commanding the DRL lamps to be illuminated, Active is displayed. When the BCM is opening the ground to the DRL relay coil and commanding the DRL lamps to be OFF, Inactive is displayed.

ALC Headlamp Relay - Value ON/OFF

This output displays the state of the BCM in controlling the ground path for the ALC headlamp relay coil, turning the low beams illumination ON or OFF.

When the BCM is grounding the ALC headlamp relay coil and commanding the low beam lamps to be illuminated, ON is displayed. When the BCM is opening the ground to the ALC headlamp relay coil and commanding the low beams headlamps not to be illuminated, OFF is displayed.

ALC Parklamp Relay - Value ON/OFF

This output displays the state of the BCM in controlling the ground circuit for the ALC parklamp relay coil, turning the low beams illumination ON or OFF.

When the BCM is grounding the ALC parklamp relay coil and commanding the low beam lamps to be illuminated, ON is displayed. When the BCM is opening the ground to the ALC parklamp relay coil and commanding the parklamps not to be illuminated, OFF is displayed.

Inadvert. Power Output - Value ON/OFF

This output displays the state of the inadvertent power output. It controls the interior lighting and protects the battery from running down.

Serial Peripheral Interface (SPI) Data Input - Value Low/High

This input displays the state of the SPI data line from the instrument cluster to the BCM.

Serial Peripheral Interface (SPI) Data Output - Value Low/High

This output displays the state of the SPI data line from the BCM to the instrument cluster.

BCM to Cluster Data

Gear Position - Value PARK / REVERSE / NEUTRAL / DRIVE / DRIVE 3 / DRIVE 2 / DRIVE 1

This data indicates what message is being sent from the BCM to the instrument cluster in order to control the illumination of the PRNDL display. The PCM reads the transaxle range switch and transmits the selected gear position information over the class 2 serial data line.

The BCM reads this gear selection information and transmits this information to the instrument cluster over the SPI serial data line. The instrument cluster turns on the correct PRNDL indicator.

Fuel Gauge Position - Range 0-250 Counts:

This data indicates what message is being sent from the BCM to the instrument cluster in order to control the fuel gauge pointer position. The BCM reads the fuel level sensor value in ohms. The sensor performs the following functions:

1. Filters the system in order to prevent fuel gauge slosh
2. Sends the fuel level information on the SPI data line in counts to the instrument cluster
3. The cluster then drives the fuel gauge pointer.

The fuel gauge SPI counts value to the fuel gauge (pointer) position ratio are included in the following table:

Serial Peripheral Interface (SPI) Count Value	Fuel Gauge Position
240 -250 Counts	Full
184	3/4 full
128	Half Full
71	1/4 Full
0-15 Counts	Empty

The BCM also transmits class 2 serial data fuel messages to the PCM for OBD ll purposes. The controller receives a class 2 serial data message from the PCM for PRNDL status.

Temp. Gauge Position - Range 0-255 Counts

This data indicates what message is being sent from the BCM to the instrument cluster in order to control the temperature gauge pointer position. The PCM performs the following functions:

1. Reads the engine coolant temperature (ECT) sensor
2. Filters the sensor
3. Sends engine coolant temperature to the BCM via the class 2 serial data line.

The PCM also monitors the ECT sensor. The PCM will set a DTC if the ECT sensor is faulty. The BCM performs the following functions:

1. Converts the PCM class 2 serial data ECT sensor message into the SPI count units
2. Sends the class 2 serial data message to the instrument cluster in an SPI message.

The instrument cluster then drives the temperature gauge pointer. The temperature gauge SPI counts value to the temperature gauge (pointer) position ratio are included in the following table:

Serial Peripheral Interface (SPI) Count Value	Temp. Gauge Position
255 Counts	127°C (260°F) (red line top)
223	123°C (253°F) (red line bottom)
128	90.5°C (195°F) (½ scale)
0 Counts	38°C (100°F) (cold)

Low Coolant Indicator - Value ON/OFF

This data indicates what message is being sent from the BCM to the instrument cluster in order to control the low coolant indicator illumination. When the BCM is commanding the instrument cluster in order to illuminate the low coolant indicator, ON is displayed. OFF is displayed if the BCM is commanding the instrument cluster not to illuminate the low coolant indicator. The engine coolant level switch, located in the coolant surge tank, is a discrete input to the BCM.

This switch will close (become active) when the engine coolant level drops below the engine coolant level switch for at least 10 seconds. The ignition switch must be in the RUN position. The BCM sends a data message to the instrument cluster in order to turn the low coolant indicator via the SPI data line. The indicator will be commanded OFF, if the engine coolant level switch input goes inactive for at least 2 seconds.

ABS Indicator - Value ON/OFF

This data indicates what message is being sent from the BCM to the instrument cluster in order to control the ABS indicator illumination. When the electronic brake control module (EBCM) transmits a class 2 serial data message to the BCM indicating there is an ABS fail condition, ON is displayed. The BCM sends a data message on the SPI data line to the instrument cluster in order to illuminate the ABS indicator.

When the BCM is sending a message to the instrument cluster not to illuminate the ABS indicator, Off is displayed. In the event of a SPI data loss, the ABS indicator will not be commanded to illuminate (remain off) unless the ABS indicator was illuminated prior to the SPI data loss.

Hi Beam Lamp - Value ON/OFF

This data indicates what message is being sent from the BCM to the instrument cluster in order to control the high beam indicator illumination. When the BCM is commanding the high beam indicator to be illuminated, indicating that the high beam headlamps are illuminated, ON is displayed. When the BCM is commanding the high beam indicator not to be illuminated, indicating that the high beam headlamps are not illuminated, OFF is displayed.

The BCM reads the high beam input voltage and divides by the system voltage in order to determine a percentage value. This value is compared against a calibration in order to determine if the high beams are ON. The controller forwards this status determination information to the instrument cluster via the SPI data line. The instrument cluster commands the high beam lamp accordingly.

Oil Pressure Lamp - Value ON/OFF

This data indicates what message is being sent from the BCM to the instrument cluster in order to control the oil pressure indicator illumination. When the BCM is commanding the oil pressure indicator to be illuminated, ON is displayed. When the BCM is commanding the oil pressure indicator not to be illuminated, OFF is displayed.

The oil pressure switch is located on the engine. This switch closes with low oil pressure at about 13.8 kPa (2 psi). This switch sends a discrete input to the PCM that in turn sends a class 2 serial data message to the BCM. This condition sends a SPI serial data message to the instrument cluster in order to illuminate the oil pressure indicator.

In the event of a class 2 serial data loss. The oil pressure indicator will not illuminate unless the oil pressure indicator was illuminated when the serial data loss occurred. In the event of a SPI data loss, the oil pressure indicator will not illuminate unless the oil pressure indicator was illuminated prior to the serial data loss.

V Indicator - Value ON/OFF

This data indicates that there is a battery charging problem with the generator. The generator information is read by the PCM and this information is sent to the BCM via the class 2 serial data bus.

Low Oil Level Indicator - Value ON/OFF

This data indicates what message is being sent from the BCM to the instrument cluster in order to control the low oil level indicator illumination. When the BCM is commanding the low oil level indicator to be illuminated, ON is displayed. When the BCM is commanding the low oil level indicator not to be illuminated, OFF is displayed.

The engine oil level switch is located in the engine oil pan. This switch closes to ground when the engine oil level is satisfactory. This switch sends a discrete input to the PCM that in turn sends a class 2 serial data message to the BCM. This condition sends a SPI serial data message to the instrument cluster in order to illuminate the low oil indicator level indicator.

In the event of a BCM or PCM class 2 serial data loss, the low oil level indicator will not illuminate unless the low oil level indicator was illuminated when the serial data loss occurred. In the event of a SPI data loss, the low oil level indicator will not illuminate unless the low oil level indicator was illuminated prior to the serial data loss.

Service Vehicle Soon Indicator - Value ON/OFF

This data indicates that there is a non-emissions related failure within the vehicle that set a diagnostic trouble code (DTC).

Low Washer Fluid Indicator - Value ON/OFF

This data indicates what message is being sent from the BCM to the instrument cluster in order to control the low washer fluid indicator illumination. When the BCM is commanding the low washer fluid indicator to be illuminated, ON is displayed. When the BCM is commanding the low washer fluid indicator not to be illuminated, OFF is displayed.

The low washer fluid switch engine is attached to the washer solvent reservoir. This switch sends a discrete input to the BCM that will close (provides a ground) when the washer fluid level drops below the switch for at least 30 seconds. The BCM in turn sends a SPI serial data message to the instrument cluster in order to illuminate the low washer level fluid indicator.

The low washer level fluid indicator will be commanded OFF when the low washer level switch input goes inactive (fluid level satisfactory for 30 seconds). In the event of a SPI data loss, the low washer level indicator will not illuminate unless the low washer level indicator was illuminated prior to the SPI data line failure.

Cruise Indicator - Value ON/OFF

This data indicates what message is being sent from the BCM to the instrument cluster in order to control the cruise indicator illumination. When the BCM is commanding the instrument cluster in order to illuminate the cruise indicator, ON is displayed. When the BCM is commanding the instrument cluster not to illuminate the cruise indicator, OFF is displayed.

With the cruise control engaged, the PCM receives an input signal from the cruise control module. The PCM sends a class 2 serial data message to the BCM. This condition sends a SPI serial data message to the instrument cluster in order to illuminate the cruise indicator.

In the event of a SPI data loss, the cruise indicator will not illuminate unless the cruise indicator was illuminated prior to the SPI data line failure.

Fuel Level Indicator - Value ON/OFF

This data indicates what message is being sent from the BCM to the instrument cluster in order to control the low fuel level indicator illumination. When the fuel level has dropped to a point below 1/8 of a tank, ON is displayed. When the fuel level has risen above 1/4 of a tank, OFF is displayed.

The BCM reads the fuel level sensor value in ohms (less than 59 ohms). The sensor is then filtered in order to prevent fuel gauge slosh from prematurely turning the low fuel level indicator ON. The BCM sends a serial SPI data message to the instrument cluster commanding the sensor to illuminate the low fuel level indicator.

Brake Indicator - Value ON/OFF

This data indicates what message is being sent from the BCM to the instrument cluster in order to control the brake indicator illumination. ON is displayed under one of the following conditions:

The BCM sends a SPI serial data message to the instrument cluster commanding the brake indicator to be illuminated when the parking brake is not engaged. When the EBCM is not sending a class 2 serial data message indicating a brake fail condition, OFF is displayed.

In the event of the EBCM commanding the brake indicator to illuminate the cruise function will be cancelled. In the event of class 2 serial data loss, the brake indicator will illuminate. In the event of an SPI data line failure the brake indicator will not illuminate unless the brake indicator was illuminated prior to the SPI data line failure.

Seat Belt Indicator- Value ON/OFF

This data indicates what message is being sent from the BCM to the instrument cluster in order to control the seat belt indicator. When the BCM is commanding the instrument cluster in order to illuminate the seat belt indicator, ON is displayed. When the BCM is commanding the instrument cluster not to illuminate the seat belt indicator, OFF is displayed.

The seat belt indicator will indicate to the driver that the seatbelt is not buckled (the seatbelt switch is active or grounded). The seat belt input should be in transition from active to inactive under the following conditions:

Upon either transition the seat belt indicator will illuminate steady for 20 seconds and flash for 55 seconds. The seat belt indicator will be OFF under the following conditions:

Theft System Indicator - Value ON/OFF

Scan tool display: this data indicates what message is being sent from the BCM to the instrument cluster in order to control the theft system indicator.

When the BCM is commanding the instrument cluster in order to illuminate the theft system indicator, ON is displayed. When the BCM is commanding the theft system indicator not to be illuminated, OFF is displayed. An illuminated theft system indicator indicates that the BCM has determined the Passlock® data has not passed.

The theft system indicator will be illuminated when any DTC is set or the PCM VTD fail-enable bit is true in the last vehicle security status message received. The BCM will not be in the auto learn mode.

The theft system indicator will flash when the BCM detects a defect or the PCM fuel disable time-out bit is set in the last vehicle security status message received since the ignition switch was turned on to the RUN position. Refer to Vehicle Theft Deterrent (VTD) Description in Theft Deterrent.

Door Ajar Indicator - Value ON/OFF

This data indicates what message is being sent from the BCM to the instrument cluster in order to control the door ajar indicator illumination. When the BCM is commanding the instrument cluster in order to illuminate the door ajar indicator, ON is displayed. This indicates to the driver that one or more doors are not closed and completely latched. When the BCM is commanding the door ajar indicator not to be illuminated, OFF is displayed.

The BCM reads the status of all door inputs and sends a SPI serial data message to the instrument cluster commanding the door ajar indicator to be illuminated. In the event of an SPI data line failure, the instrument cluster will turn the door ajar indicator OFF.

Gear Range Dim - Value ON/OFF

This data indicates what message is being sent from the BCM to the instrument cluster in order to control the gear range indicator illumination intensity. When the BCM is commanding the instrument cluster in order to illuminate the gear range indicator in a dim light intensity state, ON is displayed. When the BCM is not commanding the instrument cluster in order to illuminate the gear range indicator in a dim state (or full bright illumination state), OFF is displayed.

English/Metric State - Value ON/OFF

This data indicates what message is being sent from the BCM to the instrument cluster in order to control the English or Metric units of display.

Tach Signal Range Active/Inactive

This data indicates whether the BCM is acknowledging a tachometer signal message at the instrument cluster via the SPI serial data line. When the BCM is measuring a tachometer signal message at the instrument cluster via the SPI serial data line, Active is displayed. When the BCM is not measuring a tachometer signal message at the instrument cluster via the SPI serial data line, Inactive is displayed.

The instrument cluster receives a discrete tachometer signal from the PCM. The instrument cluster calculates the engine RPM based on the tachometer input and drives the tachometer gauge. The instrument cluster also determines if the discrete hardware input is toggling. This input sets a bit in the SPI serial data return line to the BCM.

Vehicle Speed Sensor Signal (VSS) - Value Active/Inactive

This data indicates whether the BCM is acknowledging a VSS signal at the instrument cluster via the SPI serial data line.

When the BCM is measuring a VSS signal message at the instrument cluster via the SPI serial data line, Active is displayed.

When the BCM is not measuring a VSS signal message at the instrument cluster via the SPI serial data line, Inactive is displayed.

The PCM constantly receives and converts the discrete A/C voltage signal generated by the automatic transmission output (shaft) speed sensor (A/T OSS sensor) into a digital vehicle speed signal. The PCM sends this digital vehicle speed signal information to the BCM. Other modules are also involved via the class 2 serial data line and the instrument cluster via the discrete VSS line.

The instrument cluster calculates the correct vehicle speed in order to display in km/h (mph). This is based on the VSS input that drives the speedometer and odometer accordingly.

Serial Peripheral Interface (SPI) Serial Data Status - Value OK/Fault

This data indicates whether the BCM is communicating with the instrument cluster.

OK is displayed when the BCM is communicating properly on all 3 lines.

FAULT is displayed when the BCM dictates whether the BCM is communicating with the instrument cluster.

OK is displayed when the BCM is not properly communicating with the instrument cluster on any of the 3 lines.

Division-Chevrolet/Oldsmobile

This data identifies the name of the GM division that made the vehicle's instrument cluster. One of the following names will be displayed depending on the instrument cluster GM Division application.