GM Service Manual Online
For 1990-2009 cars only

Data Display

The scan tool displays the module data. This information assists in determining whether the module is operating properly, and whether the module is sending or receiving the proper data to and from a particular system. The module uses data received from other systems in order to carry out some functions. If the module receives the incorrect data from another system, the module may function improperly. Use the scan tool in order to review the data from the systems that interact with the module.

Displayed Input/Output Status

The scan tool also displays the module input/output status. Select the module input/output status display in order to display the data and determine if the switched inputs/outputs may be properly interpreted. The display also indicates if the input/output has changed states. For example, when a door is closed, the scan tool displays the input status of the door ajar switch as INACTIVE. When the door is open, the scan tool reads ACTIVE. Use this type of information when diagnosing a malfunction associated with a particular module input or an input that is shared with another system.

Control Outputs

Use a scan tool in order to control the module output functions. When the module output control is selected, the scan tool can command the module to turn an output on or off. This feature may be used in order to determine if the module is able to control an output regardless of the inputs or any specific program instructions. Once a test is selected, the scan tool will command the module to energize the selected output. The scan tool then displays the status of the selected output. The displayed information represents only what was module commanded, not what action was actually taken. Verify that the module is performing each of the selected output functions.

Scan Tool Menus

Refer to the Scan Tool Manual for complete information on scan tool diagnostics.

Diagnostic Trouble Codes (DTC)

The diagnostic trouble codes (DTC) function has the following 3 modes:

DTC Information: Current or history DTCs stored by the EBCM/EBTCM may be displayed.

DTC History: Displays the conditions under which a history DTC was set.

Clear DTC Information: Current or history DTCs stored by the EBCM/EBTCM may be cleared.

Data Display

The data display function has the following 3 modes:

    • Normal Mode
    • Diagnostic Mode
    • Engineering Mode

A brief description of data display parameters available on the scan tool are listed below:

Normal Mode

System Content - TCS: Scan tool displays: Yes/No - Display indicates if the vehicle is equipped with TCS.

System Content - MSVA: Scan tool displays: Yes/No - Display indicates if the vehicle is equipped with Magna Steer.

TCS Status/PCM - Ready: Scan tool displays: Yes/No - Display indicates the traction control status of the PCM.

TCS Status/EBTCM - Ready: Scan tool displays: Yes/No - Display indicates the traction control status of the EBCM/EBTCM.

TCS Status/EBTCM - Inhibited: Scan tool displays: Yes/No - Display indicates the traction control status of the EBCM/EBTCM.

TCS Status/EBTCM - BTM Exceeded: Scan tool displays: Yes/No - Display indicates the if the brake thermal model has been exceeded.

TCS Off Lamp: Scan tool displays: On/Off - Display indicates the TRACTION OFF indicator status.

TCS Active Lamp: Scan tool displays: On/Off - Display indicates the TRACTION ACTIVE indicator status.

ABS/TCS System: Scan tool displays: Active/Inactive - Display indicates the ABS/TCS system status.

ABS Warning Lamp: Scan tool displays: On/Off - Display indicates the ANTILOCK indicator status.

TCS Status/PCM - TCS Active: Scan tool displays: Yes/No - Display indicates the traction control active status of the PCM.

TCS Status/EBTCM - TCS Active: Scan tool displays: Yes/No - Display indicates the traction control active status of the EBCM/EBTCM.

ABS Status/EBTCM - Failed: Scan tool displays: Yes/No - Display indicates the ABS failed status of the EBCM/EBTCM.

ABS Status/EBTCM - Active: Scan tool displays: Yes/No - Display indicates the ABS active status of the EBCM/EBTCM.

TCS Status/PCM - Inhibited: Scan tool displays: Yes/No - Display indicates the traction control inhibited status of the PCM.

TCS Status/EBTCM - Inhibited: Scan tool displays: Yes/No - Display indicates the traction control inhibited status of the EBCM/EBTCM.

TCS Status/PCM - TCS Failed: Scan tool displays: Yes/No - Display indicates the traction control failed status of the PCM.

TCS Status/EBTCM - TCS Failed: Scan tool displays: Yes/No - Display indicates the traction control failed status of the EBCM/EBTCM.

Brake Switch Status: Scan tool displays: Applied/Released - Display indicates the brake switch status.

Brake 40% Switch Status: Scan tool displays: Applied/Released - Display indicates the brake switch status.

Diagnostic Mode

Left Front Wheel Speed: Scan tool displays: km/h or mph - Display indicates the actual speed of the left front wheel.

Right Front Wheel Speed: Scan tool displays: km/h or mph - Display indicates the actual speed of the right front wheel.

Left Rear Wheel Speed: Scan tool displays: km/h or mph - Display indicates the actual speed of the left rear wheel.

Right Rear Wheel Speed: Scan tool displays: km/h or mph - Display indicates the actual speed of the right rear wheel.

Vehicle Speed: Scan tool displays: km/h or mph - Display indicates vehicle speed from the average of all four wheel speeds.

Reached 40 km/h: Scan tool displays: Yes/No - Display indicates whether the vehicle reached 40 km/h during the ignition cycle.

Ignition3 Voltage: Scan tool displays: Volts - Display indicates the current ignition voltage.

Solenoid Voltage: Scan tool displays: Volts - Display indicates the current BPMV solenoid relay voltage.

Pump Motor Feedback: Scan tool displays: Volts - Display indicates the current BPMV motor voltage.

TCS Active Lamp: Scan tool displays: On/Off - Display indicates the TRACTION ACTIVE indicator status.

TCS Switch: Scan tool displays: On/Off - Display indicates the traction control on/off switch status.

ABS Active: Scan tool displays: Yes - Display indicates the ABS status.

Solenoid Relay State: Scan tool displays: On/Off - Display indicates the BPMV solenoid relay status.

Motor Relay State: Scan tool displays: On/Off - Display indicates the BPMV motor relay status.

Brake Switch Open: Scan tool displays: Yes/No - Display indicates if the brake switch is open.

Brake Switch Status: Scan tool displays: Applied/Released - Display indicates the brake switch status.

Brake Travel Switch: Scan tool displays: Applied/Released - Display indicates the brake travel switch status.

LF Outlet Solenoid: Scan tool displays: Inactive/Active - Display indicates the state of the solenoid valve.

RR Outlet Solenoid: Scan tool displays: Inactive/Active - Display indicates the state of the solenoid valve.

RR Inlet Solenoid: Scan tool displays: Inactive/Active - Display indicates the state of the solenoid valve.

LR Inlet Solenoid: Scan tool displays: Inactive/Active - Display indicates the state of the solenoid valve.

LR Outlet Solenoid: Scan tool displays: Inactive/Active - Display indicates the state of the solenoid valve.

RF Outlet Solenoid: Scan tool displays: Inactive/Active - Display indicates the state of the solenoid valve.

RF Inlet Solenoid: Scan tool displays: Inactive/Active - Display indicates the state of the solenoid valve.

LF Inlet Solenoid: Scan tool displays: Inactive/Active - Display indicates the state of the solenoid valve.

LF TCS Isolation Valve: Scan tool displays: Inactive/Active - Display indicates the state of the solenoid valve.

RF TCS Isolation Valve: Scan tool displays: Inactive/Active - Display indicates the state of the solenoid valve.

RF TCS Prime Valve: Scan tool displays: Inactive/Active - Display indicates the state of the solenoid valve.

LF TCS Prime Valve: Scan tool displays: Inactive/Active - Display indicates the state of the solenoid valve.

Engineering Mode

Important: The data displayed by the scan tool in this mode is used during engineering development. It is not useful for the technician.

PCM Data $90 Bytes 1-4: Scan tool displays: Number - Display indicates an engineering number.

PCM Data $90 Bytes 5-8: Scan tool displays: Number - Display indicates an engineering number.

ABS Data $91 Bytes 1-4: Scan tool displays: Number - Display indicates an engineering number.

ABS Data $91 Bytes 1-4: Scan tool displays: Number - Display indicates an engineering number.

Snapshot

In this test mode, the scan tool captures the data listed in the data displays before and after a snapshot-triggering condition which may or may not set a DTC.

Special Functions

In this test mode, the scan tool may be used in order to perform functional tests on the system which help verify proper operation. Malfunction conditions may be further identified by testing and observing the test results. You must clear any DTCs before any tests in Special Functions may be performed. The Special Functions are grouped in the following manner:

    • Solenoid Test
    • Automated Bleed
    • Automated Test
    • TCS Test
    • TCS System Test
    • Lamp/Message(s) Test

The Special Functions are detailed below.

Solenoid Test-Pressure Hold

This test activates the selected wheel circuit inlet valve, placing the valve in the pressure hold position. When the valve is in the pressure hold position, the valve will not allow master cylinder pressure to be delivered to the hydraulic wheel circuit. This is done under actual operating conditions when the EBCM/EBTCM determines that the wheel is moving too slowly. The EBCM/EBTCM holds additional master cylinder pressure from the hydraulic wheel circuit in an attempt to allow the circuit to rotate at an appropriate speed. The scan tool commands the valve to close. This should allow the technician to spin the wheel even though an assistant is applying pressure to the brake pedal. Perform the following test:

  1. Turn the ignition switch to the OFF position.
  2. Connect a scan tool to the data link connector (DLC).
  3. Turn the ignition switch to the RUN position.
  4. Raise the vehicle. Ensure that all of the wheels are about 15 cm (6 in) off of the floor.
  5. Place the gear selector in the NEUTRAL position.
  6. Select the Special Functions from the ABS/TCS menu.
  7. Select the Solenoid Test. Have an assistant command Inlet Valve Solenoid of the appropriate wheel using the scan tool.
  8. Have the assistant press and hold the brake pedal.
  9. Attempt to move the wheel being tested by hand. The wheel should move even though the assistant is applying pressure to the brake pedal. The front wheels may be difficult to turn by hand, but may be moved if the system is working properly.

Solenoid Test-Pressure Release

This test activates the selected hydraulic wheel circuit outlet valves, placing them in the pressure reduce position. When in the pressure reduce position, the valve will allow wheel caliper pressure to be returned to the master cylinder circuit. This is done under actual operating conditions because the EBCM/EBTCM has determined that the wheel is moving too slowly, and holding additional master cylinder pressure from it has not allowed it to rotate at an appropriate speed. The scan tool commands the valves to these positions which should allow the technician to spin the wheel even though an assistant is applying pressure to the brake pedal. Perform the following test:

  1. Turn the ignition switch to the OFF position.
  2. Connect a scan tool to the data link connector (DLC).
  3. Turn the ignition switch to the RUN position.
  4. Raise the vehicle. Ensure that all of the wheels are about 15 cm (6 in) off of the floor.
  5. Place the gear selector in the NEUTRAL position.
  6. Select the Special Functions from the ABS/TCS menu.
  7. Select the Solenoid Test. Have an assistant command the Outlet Valve Solenoid of the appropriate wheel using the scan tool.
  8. Have the assistant press and hold the brake pedal.
  9. Attempt to move the wheel being tested by hand. The wheel should move even though the assistant is applying pressure to the brake pedal. The front wheels may be difficult to turn by hand, but may be moved if the system is working properly.

Automated Bleed

The Automated Bleed mode of the scan tool is used during bleeding of the ABS System. Refer to Antilock Brake System Automated Bleed Procedure .

Automated Test

This test cycles each valve solenoid and the pump motor (as well as the necessary relays) in order to verify component operation. This test is identical to the Initialization Sequence. If a malfunction is detected, the EBCM/EBTCM will set DTCs. The DTCs will be displayed upon completion of the test. Perform the following test:

  1. Turn the ignition switch to the OFF position.
  2. Connect a scan tool to the data link connector (DLC).
  3. Turn the ignition switch to the RUN position.
  4. Select the Special Functions from the ABS/TCS menu.
  5. Select the Automated Test.
  6. Run the Automated Test.
  7. Record any DTCs that were set.

TCS Test

This test runs the pump motor in order to apply fluid pressure to the front wheel circuits.

Perform the following test. This test does NOT require an assistant:

  1. Turn the ignition switch to the OFF position.
  2. Connect a scan tool to the data link connector (DLC).
  3. Turn the ignition switch to the RUN position.
  4. Place the gear selector in the NEUTRAL position.
  5. Raise the vehicle. Ensure that all of the wheels are about 15 cm (6 in) off of the floor.
  6. Select the Special Functions from the ABS/TCS menu.
  7. Select the TCS Test.
  8. Command the TCS Test ON with the scan tool. The pump motor will turn on for approximately 25 seconds.
  9. Attempt to move each front wheel by hand. The wheels should not move due to the pump motor running and applying pressure to the front wheels.

TCS System Test

This test checks for proper communication between the EBCM/EBTCM and the PCM. The scan tool will report any possible problems.

Lamp/Message(s) Test

This test controls the following indicators:

    • ANTILOCK LAMP
    • TCS ACTIVE
    • TCS OFF