The typical scan tool readings of body control module (BCM) data will assist in diagnosing a problem. The scan tool data displays may be viewed while the vehicle is being driven.
The typical scan tool data definitions represent general information displayed on the scan tool regarding the following items:
| • | BCM functions |
| • | Ignition inputs |
| • | Basic operating conditions |
The data messages and menu headings displayed on the scan tool are defined below.
Module Information 1
Module Part Number
Range: 16XXXXXX
This information refers to the part number assigned to the BCM that is currently in the vehicle.
Manufacturer Enable Counter
Range : 0-255
This information refers to the actual value for the manufacturers enable counter (MEC) in the BCM. This information is for the assembly plant use only.
Software Part Number
Range: 16XXXXXX
This information refers to the version of the software ID (software identification number) in the BCM.
Software Design Suffix
Range: AA-ZZ
This information refers to the version of the software part number in the BCM.
Module Information 2
RAP Calibration Number
Range 16XXXXXX
This information refers to the RAP calibration part number in the BCM.
RAP Suffix
Range: AA-ZZ
This information refers to the RAP identification number in the BCM.
Lighting Calibration Number
Range 16XXXXXX
This information refers to the lighting configuration calibration part number in the BCM.
Lighting Suffix
Range: AA-ZZ
This information refers to the lighting configuration identification number in the BCM.
Reminder Calibration Number
Range: 16XXXXXX
This information refers to the reminder warning calibration part number in the BCM.
Reminder Suffix
Range: AA-ZZ
This information refers to the reminder warning identification number in the BCM.
Security Calibration Number
Range: 16XXXXXX
This information refers to the security calibration part number in the BCM.
Security Suffix
Range: AA-ZZ
This information refers to the security identification number in the BCM.
Data
Dimming Potentiometer
Range: 0.0-18.0 volts
The voltage value displayed indicates the position of the dome lamp switch (thumb wheel). Zero (0) volts will be displayed when the following conditions exist:
| • | The headlamp switch is in the AUTO position. |
| • | The daytime running lamps are OFF. |
10.5 volts will be displayed when the following conditions exist:
| • | The park lamps or the headlamps are turned ON. |
| • | The dome lamp switch is in the FULL bright position (thumb wheel turned completely up just before the detent). |
0.1 volts will be displayed if the following conditions exist:
| • | The park lamps or the headlamps are turned ON. |
| • | The dimmer switch is in the FULL DIM position (thumbwheel turned completely down). |
The dimming potentiometer voltage will change as the dome lamp switch is moved between FULL BRIGHT and FULL DIM. The voltage value displayed should vary between 0.1-12.7 volts depending on the position of the dome lamp switch.
Battery Voltage
Range: 0-18.0 volts
The voltage value displayed refers to the battery system voltage measured by the BCM.
Ambient Light Sensor
Range: 0-5.0 volts
The displayed voltage value refers to the amount of ambient light level as measured by the light sensor. This information is used by the BCM in order to operate the automatic headlamp feature and the daytime running lamps (DRL) feature. The BCM supplies 5 volts to the ambient light photocell sensor and receives a return signal voltage from the ambient light photocell on the return signal circuit. The ambient light sensor internal resistance changes with different levels of ambient light. In LIGHT ambient conditions, the resistance is low. In DARK ambient conditions, the resistance is high.
The BCM interprets the following conditions as LIGHT:
| • | The ambient light sensor is exposed to bright ambient light (low resistance). |
| • | High voltage (2.2-4.7 volts) is present on the return circuit. |
The BCM interprets the following conditions as DARK:
| • | The ambient light sensor is exposed to dark ambient light. |
| • | Internal resistance increases. |
| • | The return signal voltage decreases (0.2-1.3 volts). |
If there is an open or a short to ground in the ambient light sensor circuit, the sensor will read about 0.0 volts. The BCM will default into a DARK state and turn ON the headlamps.
If the headlamps are set to the AUTO position while in the LIGHT state and the ambient light level conditions change to DARK for 15 seconds, the BCM will turn ON the headlamps.
If the headlamps are set to the AUTO position while the DARK state and the ambient light level conditions change to LIGHT for 20 seconds, the BCM will turn the headlamps OFF.
Ambient Light
Range: Light/Dark
The displayed value refers to the amount of ambient light level calculated by the BCM using the light sensor.
The information is used by the BCM for operation of the following features:
| • | The automatic headlamp feature |
| • | The daytime running lamps (DRL) feature |
The BCM supplies 5 volts to the ambient light photocell sensor and receives a return signal voltage from the ambient light photocell sensor on the return signal circuit.
The following actions will occur if there is an open or a short to ground in the ambient light sensor circuit:
| • | The scan tool will display DARK. |
| • | The BCM will default into a DARK state and turn the headlamps ON. |
If the headlamps are set to the AUTO position while in the LIGHT state and the ambient light level conditions change to DARK for 15 seconds, the BCM will turn the headlamps ON.
If the headlamps are set to the AUTO position while the DARK state and the ambient light level conditions change to LIGHT for 20 seconds, the BCM will turn the headlamps OFF.
Dusk
YES/NO
The displayed value refers to the dimming signal output from the BCM. This information is used by the BCM for the operation of the following features:
| • | Automatic headlamp |
| • | Daytime running lamps (DRL) feature |
Dusk is displayed whenever the park lamps are ON.
High Beam Input
Range: 0.0-18.0 Volts
The BCM uses this input in order to determine the state of the high beam headlamps. The BCM measures the circuit voltage at a point between both of the high beam headlamps and the beam selector switch. The high beam input voltage will vary depending on the state of the headlamps.
Refer to the following table.
Headlamps State | High Beam Input Voltage |
|---|---|
DRL Beams ON | 5.9-7.0 volts |
Low Beams ON | 11.5-14.0 volts |
High Beams ON | 1.2 volts |
Vehicle Speed
Range: 0-205 km/h (0-127 mph)
The BCM uses the data for determining how fast the vehicle is traveling. The BCM uses this data for the operation of the following features:
| • | Automatic door lock feature |
| • | Turn signal reminder feature |
Inadvertent Power Timer
Range: 0-1216 seconds
The BCM uses this feature to protect the battery against inadvertent battery rundown caused by devices that attach to the courtesy lamp circuit. If the following lights remain ON, the BCM will turn the lights OFF after 20 minutes:
| • | The dome/courtesy lamp |
| • | The vanity lamp |
| • | The underhood or the glove box lamp |
The lights are turned OFF by the inadvertent power relay. The inadvertent power relay supplies power to the courtesy lamp circuit when the ignition is in the OFF position. The number of seconds displayed refers to the amount of time left before the BCM will turn the relay OFF.
RAP Timer
Range: 0-1198 seconds
The BCM uses this feature to control the devices that attach to the retained accessory power (RAP) circuit. This feature allows the operation of the following components for 20 minutes after the ignition key is turned to the OFF position and before any door is opened:
| • | The radio |
| • | The power windows |
When any door is opened or after 20 minutes, the BCM opens the ground circuit for the RAP relay. The following components will turn OFF:
| • | The radio |
| • | The power windows |
The number of seconds displayed refers to the amount of time left before the BCM will turn OFF the RAP relay. The BCM uses the data in order to control the power to the RAP circuit.
Courtesy Lamp Timer
Range: 0-40 seconds
The BCM uses the courtesy lamp timer in order to control the devices that attach to the following circuits:
| • | Illuminated entry -- The courtesy lamps will turn ON when you enter the vehicle. The lamps will stay ON for 15 seconds or until the ignition switch is turned to the ON position. |
| • | Exit lighting -- The courtesy lamps will turn ON when the key is removed from the ignition switch. The lamps will remain ON for 40 seconds. The number of seconds displayed refers to the amount of time left before the BCM turns the courtesy lamp relay OFF. |
Input 1
Ignition 1
Range: ACTIVE/ INACTIVE
The BCM uses the Ignition 1 data in order to determine the position of the ignition switch.
ACTIVE is displayed when the ignition switch is in the RUN or CRANK position.
INACTIVE is displayed when the ignition switch is not in the RUN or CRANK position.
Ignition 3
Range: ACTIVE/ INACTIVE
The BCM uses the Ignition 1 data in order to determine the position of the ignition switch.
ACTIVE is displayed when the ignition switch is in the RUN position.
INACTIVE is displayed when the ignition switch is not in the RUN position.
Ignition Power Mode
Range: OFF/ RUN/ CRANK/ UNKNOWN
The BCM uses the ignition power mode data in order to determine the position of the ignition switch.
OFF is displayed when the ignition switch is in the OFF or the ACCESSORY positions.
RUN is displayed when the switch is in the RUN position.
CRANK is displayed when the ignition switch is in the CRANK position.
UNKNOWN is displayed when the BCM cannot determine the position of the ignition switch (i.e. between the OFF and the RUN position).
Door Handle Switch
Range: ACTIVE/ INACTIVE
The door handle switch information refers to the position of either of the door handles (outside or inside). The information is used by the BCM for the illuminated entry feature.
ACTIVE is displayed when either of the handles is raised.
INACTIVE is displayed when neither of the front door handles is raised. The right front door jamb switch is also on the circuit.
ACTIVE is displayed when the right front door is opened.
INACTIVE is displayed when the right front door is completely closed.
Driver Door Jamb Switch
Range: ACTIVE/ INACTIVE
The driver door jamb switch information refers to the position of the driver door.
INACTIVE is displayed when the driver door is closed and the switch plunger is pushed in.
ACTIVE is displayed when the driver door is open and the switch plunger is out.
Key In Ignition
Range: YES/ NO
The key in ignition information refers to the position of the ignition key in the ignition switch.
YES displays when you completely insert the ignition key in the ignition switch cylinder.
NO displays when you do not completely insert the ignition ley into the ignition switch cylinder.
The BCM uses the data in order to control the operation of the key in ignition warning chime feature.
Seat Belt Buckled
Range: YES/ NO
The seat belt buckled information refers to the position of the driver seat belt buckle.
YES displays when you buckle the driver seat belt buckle (switch opened).
NO displays when you do not buckle the driver seat belt buckle (switch closed).
The BCM uses the data in order to control the operation of the seat belt warning chime.
Park Brake Switch
Range: SET/ RELEASED
The park brake switch information refers to the position of the park brake pedal.
SET displays when you depress the parking brake (switch closed).
RELEASED displays when you do not depress the parking brake switch (switch opened).
The BCM uses the data in order to control the operation of the following items:
| • | The parking brake ON warning light feature |
| • | The DRL system |
RAP Relay Feedback
Range: ON/ OFF
The RAP feedback information refers to the operation of the retained accessory power (RAP) circuit. ON displays whenever the BCM turns ON the RAP relay. The RAP relay then allows the following components to operate:
| • | The radio |
| • | The power windows |
Passenger Door Unlock Input
Range: ACTIVE/ INACTIVE
The passenger door unlock input information refers to the operation of the following items:
| • | Passenger door(s) unlock function |
| • | Passenger door unlock relay |
ACTIVE displays whenever the passenger door unlock relay coil is energized. An energized coil allows current to flow to the lock/unlock motors.
INACTIVE displays whenever the passenger door unlock relay is not energized. This condition prevents current from reaching the lock/unlock motors.
Door Lock Relay Feedback
Range: ON/ OFF
The door lock relay feedback information refers to the operation of the following items:
| • | Power door locks |
| • | Power door lock relay |
ON displays when the BCM senses the door lock relay coil is energized. This allows the current to flow to the lock/unlock motors.
OFF displays when the BCM does not sense that the door lock relay coil is being energized.
Horn Relay Input
Range: ACTIVE/ INACTIVE
The horn relay input information refers to the horn operation.
ACTIVE displays when the following conditions exist:
| • | The BCM senses that the horn relay coil circuit is grounded. |
| • | The horns receive a command to sound. |
INACTIVE displays when the following conditions exist:
| • | The BCM does not sense that the horn relay coil circuit is grounded. |
| • | The horns do not receive a command to sound. |
Input 2
Interior Lamp Request
Range: ACTIVE/ INACTIVE
The interior lamp request information refers to the interior lamp request circuit.
ACTIVE displays momentarily when the driver turns the interior lamp ON and the inadvertent power relay is ON.
INACTIVE displays when the inadvertent power relay is ON.
Headlamp Request Switch
Range: ACTIVE/ INACTIVE
The BCM uses the headlamp request switch input in order to determine the position of the headlamp switch.
ACTIVE displays when the headlamp switch is in the HEADLAMP position.
INACTIVE displays when the headlamp switch is not in the HEADLAMP position.
Headlamp Relay Feedback
Range: ON/ OFF
The BCM uses the headlamp Relay Feedback input in order to determine if the headlamps are ON or OFF by determining if current is present on the headlamp circuit. The BCM monitors CKT 352 in order to determine if the headlamp power relay energizes.
ON displays when the BCM receives a voltage input on the circuit between the headlamp switch and the headlamp power relay coil. The voltage input indicates that the headlamps are ON.
OFF displays when the BCM does not receive a voltage signal on the circuit between the headlamp switch and the headlamp power relay coil. The lack of voltage indicates that the headlamps are OFF.
High Beam Switch
Range: ON/ OFF
The BCM uses the high beam switch input in order to determine if the high beam headlamps are ON by measuring the voltage on CKT 524 between the following components:
| • | Both of the high beam headlamps |
| • | The high/ low beam selector switch |
| • | The flash to pass switch |
Flash to Pass
Range: ON/ OFF
The BCM monitors the flash to pass input on CKT 1356 in order to determine if the high beams are requested ON. The scan tool displays ON when the BCM or the flash to pass switch commands the high beams ON. OFF is displayed when the flash to pass switch or the BCM is not commanding the high beams ON.
Park Lamps
Range: ON/ OFF
The BCM monitors the voltage on the park lamp CKT 2409 in order to determine if the park lamps are ON. The scan tool displays ON when the BCM or the headlamp switch turns the park lamps ON. OFF displays when the neither the park lamp switch nor the BCM commands the park lamps to turn ON.
Daytime Running Lamps
Range: ON/ OFF
The BCM monitors the state of the daytime running lamps in order to determine if the daytime running lamps are ON.
The scan tool displays ACTIVE when the BCM commands the daytime running lamps to turn ON.
INACTIVE displays when the BCM does not command the DRL to turn ON.
Left Turn Signal
Range: ON/ OFF
The BCM uses the left turn signal input in order to determine the state of the left turn signal.
ON displays when the left turn signal switch engages. This commands the left turn signal lamps to illuminate.
OFF displays when the left turn signal switch does not engage or the turn signal lamps do not illuminate.
The BCM monitors the vehicle speed input for activation of the turn signal reminder chime feature. The scan tool display alternates between ON and OFF as the turn signal flashes.
Right Turn Signal
Range: ON/ OFF
The BCM uses the right turn signal input in order to determine the state of the right turn signal.
ON displays when the right turn signal switch engages. This commands the right turn signal lamps to illuminate.
OFF displays when the right turn signal switch does not engage or the turn signal lamps do not illuminate.
The BCM monitors the vehicle speed input for activation of the turn signal reminder chime feature. The scan tool display alternates between ON and OFF as the turn signal flashes.
Front Fog Lamp Switch
Range: ON/ OFF
The BCM uses the front fog lamp switch input in order to determine the status of the front fog lamp switch.
ON displays when you depress the front fog lamp switch.
OFF displays when you are not depressing the front fog lamp switch.
Dome Lamp Switch
Range: ON/ OFF
The BCM uses the dome lamp switch input in determining if the dome lamp switch (thumb wheel) is requesting the interior lights to turn ON.
ON displays if the dome lamp switch requests the BCM to turn the interior lights ON (full up position past the detent).
OFF displays when the dome lamp switch does not request the BCM to turn the interior lights ON (not in the full up position past the detent).
Dome Override Switch
Range: ON/ OFF
The BCM uses the dome override switch input from the dome override switch in order to allow or to defeat the interior lighting when the door opens. The dome override switch is located near the headlamp switch.
ON displays if the dome override switch is overriding the interior lighting.
OFF displays if the dome override switch allows the interior lights to turn ON when any door opens or if the left glass opens (if equipped).
Dim Pot Input
Range: ACTIVE/ INACTIVE
The BCM uses the dim pot input in order to determine the position of the dome lamp switch (thumb wheel) when the park lamps are ON.
ACTIVE displays when the dome lamp switch is not in the FULL DOWN position and the park lamps are ON.
INACTIVE displays when you turn the dome lamp switch to the FULL DOWN position (dash lights OFF) and the park lamps are ON.
The headlamp reminder chime does not sound under the following conditions:
| • | The dome lamp switch (thumbwheel) is in the FULL DOWN position (MAX DIM). |
| • | You turn the park lamps ON manually. |
| • | You remove the ignition key. |
Courtesy Lamp Relay
Range: ON/ OFF
The BCM uses the courtesy lamp relay input in order to determine the state of the courtesy lamp relay.
ON displays when the BCM commands the courtesy lamps to turn ON by providing a ground for the courtesy lamp relay coil.
OFF displays when the BCM is not commanding the courtesy lamps to turn ON by not providing a ground for the courtesy lamp relay coil.
Auto Headlamps Enable
Range: YES/ NO
The output refers to the BCM commanded state of the auto headlamp feature.
YES displays when the BCM commands the auto headlamps to turn ON.
NO displays when the BCM commands the auto headlamps to turn OFF.
Auto Headlamps
Range: ACTIVE/ INACTIVE
The BCM uses the auto headlamps input in order to determine if the auto headlamps are ON.
ACTIVE displays when the auto headlamps are ON.
INACTIVE displays when the auto headlamps are OFF.
Outputs
Chime
Range: NONE/ HEADLAMP/ KEY IN IGNITION/ SEAT BELT/ TURN SIGNAL
The chime output refers to the commanded state of the audible chime.
NONE displays when no audible chime sound is commanded.
HEADLAMP displays when the headlamp ON reminder feature commands the chime to turn ON.
KEY IN IGNITION displays when the key in ignition reminder feature and the driver door open feature command the chime to turn ON.
SEAT BELT displays when the driver seat belt not buckled reminder feature commands the chime to turn ON.
TURN SIGNAL displays when the turn signal ON reminder feature (on for more than 0.75 mile) commands the chime to turn ON.
Interior Lighting Mode
Range: NONE/ INTERIOR/ ILLUM ENTRY/ EXIT LIGHTING/ REMOTE ILLUM
The interior lighting mode output displays the name of the feature that is commanding the interior lights to turn ON.
NONE displays when the interior lights are not commanded to turn ON.
INTERIOR displays when the dome lamp switch commands the interior lights to turn ON.
ILLUM, ENTRY, EXIT LIGHTING, REMOTE ILLUM. display when the respective mode commands the interior lighting to turn ON.
Inadvertent Power Relay
Range: ON/ OFF
The inadvertent power relay output refers to the commanded state of the inadvertent power relay coil.
ON displays when the BCM commands the inadvertent power relay coil to energize. The command allows the relay to power up the following components:
| • | The courtesy lamp relay |
| • | The vanity lamps |
| • | The underhood lamps |
| • | The glove box lamp |
OFF displays when the BCM does not command the inadvertent power relay coil to turn ON. The inadvertent power relay coil then does not allow current to the following components:
| • | The courtesy lamp relay |
| • | The vanity lamps |
| • | The underhood lamp |
| • | The glove box lamp |
RAP Relay
Range: ON/ OFF
The RAP relay output refers to the commanded state of the RAP relay coil.
ON displays when the BCM commands the RAP relay coil to energize. The command allows the relay to power up the following components:
| • | The radio |
| • | The power windows |
OFF displays when the BCM commands the RAP relay to turn OFF.
Headlamp Power Relay
Range: ON/ OFF
The headlamp power relay output refers to the commanded state of the headlamp power relay coil.
ON displays when the BCM commands the headlamp power relay coil to turn ON.
OFF displays when the BCM does not command the headlamp power relay coil to turn ON.
The BCM then does not allow current to the headlamp power relay coil. The headlamps remain OFF.
DRL Relay
Range: ON/ OFF
The DRL relay output refers to the commanded state of the DRL relay coil.
ON displays when the BCM commands the DRL relay coil to turn ON. This allows the relay to power up the daytime running lamps.
OFF displays when the BCM does not command the DRL relay coil to turn ON. This denies current to the DRL relay coil and causes the daytime running lamps to be OFF.
Park Lamp Relay
Range: ON/ OFF
The park lamp relay output refers to the commanded state of the park lamp relay coil.
ON displays when the BCM commands the park lamp relay coil to turn ON. This allows the relay to power up the park lamps.
OFF displays when the BCM does not command the park lamp relay coil to turn ON.
This denies current to the park lamps and causes the park lamps to be OFF.
Front Fog Lamp Relay
Range: ON/ OFF
The front fog lamp relay output refers to the commanded state of the front fog lamp relay coil.
ON displays when the BCM commands the front fog lamp relay coil to turn ON. This allows the relay to power up the front fog lamps.
OFF displays when the BCM does not command the front fog lamp relay coil to turn ON. This denies current to the front fog lamps and causes the front fog lamps to remain OFF.
Courtesy Lamp Relay
Range: ON/ OFF
The courtesy lamp relay output refers to the commanded state of the courtesy lamp relay coil.
ON displays when the BCM commands the courtesy lamp relay coil to turn ON. This allows the relay to power up the courtesy lamps, and causes the courtesy lamps to turn ON. OFF displays when the BCM does not command the courtesy lamp relay coil to turn ON. This causes the courtesy lamps to remain OFF.
Dimming
Range: ACTIVE/ INACTIVE
The dimming output refers to the state of the headlamp switch dimming feature. The headlamp switch dimming feature is a term describing the customer's ability to control the illumination of the following components:
| • | The instrument panel cluster |
| • | The radio |
| • | The HVAC controls |
| • | The PRNDL |
| • | The PSIR switch with the dome lamp switch (thumbwheel) near the headlamp switch |
The up and down movement of the dome lamp switch allows the customer the ability to control the brightness of the components.
INACTIVE displays when the park lamps are OFF.
ACTIVE displays when the park lamps are ON.
Door Lock Relay
Range: ON/ OFF
The door lock relay output refers to the commanded state of the door lock relay coil.
ON displays when the BCM commands the door lock relay coil to turn ON.
ON displays when you press the power lock button.
OFF displays when you do not press the power lock button.
Driver Door Unlock Relay
Range: ON/ OFF
The driver door unlock relay output refers to the commanded state of the driver door unlock relay coil.
ON displays when the BCM commands the driver door unlock relay coil to turn ON.
ON momentarily displays when an input from the power door unlock switches. This causes the BCM to unlock the driver door.
OFF displays when the BCM does not command the driver door unlock relay coil to turn ON and the driver door unlock relay does not energize.
Passenger Door Unlock Relay
Range: ON/ OFF
The passenger door unlock relay output refers to the command state of the passenger door unlock relay coil.
ON displays when the BCM commands the passenger door unlock relay coil to turn ON.
OFF displays when you use the passenger power door unlock button.
Horn Relay
Range: ON/ OFF
The horn relay output refers to the commanded state of the horn relay coil. The horn button and the RFA transmitter panic button are inputs to the BCM. The BCM supplies a ground to the horn relay coil and sounds the horns.
ON displays when the BCM commands the horn relay coil to turn ON when you perform the following steps:
- Press the horn button.
- Press the transmitter panic button.
OFF displays when the BCM does not command the horn relay coil to turn ON and neither the RFA transmitter panic button nor the horn button are pressed.
Security Data
Ignition 1
Range: ACTIVE/ INACTIVE
The BCM uses the Ignition 1 data in order to determine the position of the ignition switch.
ACTIVE displays when the ignition switch is in the RUN or CRANK position.
INACTIVE displays when the ignition switch is not in the RUN or CRANK position.
Ignition 3
Range: ACTIVE/ INACTIVE
The BCM uses the Ignition 3 data in order to determine the position of the ignition switch.
ACTIVE displays when the ignition switch is in the RUN position.
INACTIVE displays when the ignition switch is not in the RUN position.
Battery Voltage
Range: 0.0-16.0 volts
The voltage value that displays refers to the battery system voltage measured by the BCM on CKT 1140.
Content Theft Lamp
Range: ON/ OFF/ FLASHING
The security lamp turns ON for 15 seconds and then turns OFF when you open a door by using the handle or the key fob. The security lamp also displays ON STEADY for 3 seconds and then turns OFF when the ignition switch turns from the OFF position to the RUN position. The security telltale has the following 3 states:
| • | OFF |
| • | ON STEADY |
| • | FLASHING |
If the IPC is unable to communicate with the BCM, the security telltale displays ON STEADY and the Passlock™ system functions. The security telltale goes to FLASHING mode momentarily and then displays ON STEADY for approximately 10 minutes if the vehicle is in the lockout cycle. The Passlock™ system requires 3 consecutive lockout cycles in order to complete the 30 minute learn procedure for a changed component. Refer to Theft Deterrent on the theft deterrent system.
