GM Service Manual Online
For 1990-2009 cars only
Table 1: ABS Data
Table 2: TCS Data
Table 3: Controller Information
Table 4: TIM Data

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

Diagnostic Trouble Codes (DTC)

The Diagnostic Trouble Codes (DTC) function has three modes that are described below:

    • DTC Information: In this mode, current or history DTC(s) stored by the EBTCM/EBCM can be displayed.
    • Enhanced Data: In this mode, DTC data for current or history DTC(s) is displayed. This data includes the following information at the time when the DTC(s) was set:
       - Brake switch status
       - TCS switch status
       - ABS activity status
       - TCS activity status
       - Vehicle speed
       - The number drive cycles since the DTC was set
    • Clear DTC Information: In this mode, current or history DTC(s) stored by the EBTCM/EBCM can be cleared.

Data Display

The Data Display function contains six sets of menus. The menus available depend on the number and type of systems on the vehicle and are listed below:

    • ABS Data
    • TCS Data
    • Controller Information
    • TIM Data

A listing of all data parameters available on the scan tool are below:

ABS Data

Scan Tool Parameter

Unit Displayed

Left Front Wheel Speed

Km/h (MPH)

Right Front Wheel Speed

Km/h (MPH)

Left Rear Wheel Speed

Km/h (MPH)

Right Rear Wheel Speed

Km/h (MPH)

Vehicle Speed

Km/h (MPH)

Rough Road Parameter

g

ABS Active

Yes/No

ABS Warning Lamp

On/Off

Brake Switch Status

Applied/Release

Brake Fluid Level

Low/OK

Ignition Voltage

Volts

Switched Battery Voltage

Volts

ABS Relay Command

On/Off

ABS Relay Feedback

On/Off

Pump Motor Commanded State

On/Off

Pump Motor Feedback State

On/Off

LF Inlet Valve Solenoid

Active/Inactive

LF Outlet Valve Solenoid

Active/Inactive

RF Inlet Valve Solenoid

Active/Inactive

RF Outlet Valve Solenoid

Active/Inactive

LR Inlet Valve Solenoid

Active/Inactive

LR Outlet Valve Solenoid

Active/Inactive

RR Inlet Valve Solenoid

Active/Inactive

RR Outlet Valve Solenoid

Active/Inactive

TCS Data

Scan Tool Parameter

Unit Displayed

Left Front Wheel Speed

Km/h (MPH)

Right Front Wheel Speed

Km/h (MPH)

Left Rear Wheel Speed

Km/h (MPH)

Right Rear Wheel Speed

Km/h (MPH)

Vehicle Speed

Km/h (MPH)

Rough Road Parameter

g

EBTCM to PCM Requested Torque

0-100% of duty cycle

PCM to EBTCM Delivered Torque

0-100% of duty cycle

Brake Temp Status

Overtemp/Normal

LF Rotor Temperature

°C (°F)

RF Rotor Temperature

°C (°F)

TCS Failed

Yes/No

TCS Active

Yes/No

TCS Enable Status

Enable/Disable

TCS Active Lamp

On/Off

TCS Disable Lamp

On/Off

TCS Warning Lamp

On/Off

Controller Information

Scan Tool Parameter

Unit Displayed

DE Base Part Number

4 characters

DE ROM Part Number

4 characters

DE Calibration Part Number

4 characters

DE End Model Part Number

4 characters

DE Build Sequence Number

8 characters

Julian Date Code

8 characters

System ID

4 characters

Configuration ID

4 characters

DRP Equipped

Yes/No

ETS Equipped

Yes/No

TCS Equipped

Yes/No

TIM Equipped

Yes/No

VES Equipped

Yes/No

TIM Data

Data Parameter

Display Status

Left Front Wheel Speed

Km/h (MPH)

Right Front Wheel Speed

Km/h (MPH)

Left Rear Wheel Speed

Km/h (MPH)

Right Rear Wheel Speed

Km/h (MPH)

TIM Failed

Yes/No

TIM Reset Switch

Pressed

Auto Learn Mode Active

Yes/No

Check Tires

Yes/No

Definitions:

    • Front Wheel Speed--Display shows actual wheel speed of either the left or right front wheel.
    • Rear Wheel Speed--Display shows actual wheel speed of either the left or right rear wheel.
    • Engine Speed--Display shows actual vehicle speed.
    • Rough Road Parameter--This parameter, calculated from wheel speed sensor data, represents the rapid variation or acceleration in g's of the driven wheel speeds due to a rough road. A rough road will cause torque to be applied to the drivetrain which may be detected by the PCM's OBD II misfire diagnostic as a false misfire. This rough road detection data is sent to the PCM via serial data. The PCM will disable the OBD II misfire diagnostic during rough road detection since this could be interpreted as misfire.
    • ABS Active--This parameter indicates if the ABS is currently in a ABS event or not.
    • ABS Warning Lamp--This indicates the state of the ANTILOCK indicator.
    • Brake Switch Status--This parameter indicates the state of the brake switch.
    • Brake Fluid Level--This parameter indicates the state of the brake fluid level.
    • Ignition Voltage--This parameter is the ignition voltage at the EBTCM.
    • Switched Battery Voltage--This parameter is the battery voltage available at the solenoid valves and the pump motor when the solenoid valve control relay is energized.
    • ABS Relay Command--This display indicates the commanded state of the solenoid valve control relay.
    • ABS Relay Feedback--This display indicates the actual state of the solenoid valve control relay.
    • Pump Motor Commanded State--This display indicates the commanded state of the ABS pump motor.
    • Pump Motor Feedback State--This display indicates the actual state of the ABS pump motor.
    • Inlet Valve Solenoid--This display indicates the commanded state of the specific inlet solenoid valve.
    • Outlet Valve Solenoid--This display indicates the commanded state of the specific outlet solenoid valve.
    • EBTCM to PCM Requested Torque--This parameter represents the requested engine torque from the EBCTM to the PCM.
    • PCM to EBTCM Delivered Torque--This parameter represents the delivered engine torque from the PCM to the EBTCM.
    • Brake Temp Status--Parameter displays a high temperature condition with the braking system which will inhibit TCS operation.
    • LF Rotor Temperature--Parameter displays a calculated temperature value of the LF rotor.
    • RF Rotor Temperature--Parameter displays a calculated temperature value of the RF rotor.
    • TCS Failed--This parameter indicates if the TCS is inactive due to a malfunction.
    • TCS Enable Status-- This parameter indicates the state of the TCS based on if the operator has disabled TCS by pressing the Traction Control switch, or if the TCS is disabled because of a malfunction.
    • TCS Active--This parameter indicates if the TCS is currently in a TCS event or not.
    • TCS Active Lamp--This parameter indicates if the TCS is currently in a TCS event.
    • TCS Warning Lamp--This indicates the state of the TRAC OFF indicator.
    • TCS Disable Lamp--This indicates if the TCS has been disabled by the driver.
    • TIM Failed--This parameter indicates if the TIM is inactive due to a malfunction.
    • TIM Reset Switch--This parameter indicates the state of the TIM reset switch.
    • Auto Learn Mode--Parameter displays whether or not vehicle is in process of Auto Learn after a TIM reset condition has begun.
    • Check Tires--Parameter indicates that the EBTCM has detected a low tire condition.

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 can be used to perform functional tests on the ABS/TCS which help verify proper operation. Malfunction conditions can be further identified by testing and observing the test results. DTCs must be cleared before any tests in Special Functions can be performed. In a vehicle equipped with ABS/TCS, the Special Functions are as following:

    • Automated Bleed Procedure.
    • ABS Relay Test.
    • Automated Test.
    • Solenoid Tests.
       - Right Rear Inlet Valve Solenoid
       - Right Rear Outlet Valve Solenoid
       - Right Front Inlet Valve Solenoid
       - Right Front Outlet Valve Solenoid
       - Left Rear Outlet Valve Solenoid
       - Left Rear Inlet Valve Solenoid
       - Left Front Inlet Valve Solenoid
       - Left Front Outlet Valve Solenoid

Lamp Test

To do a lamp test you must use the scan tool and be in the Instrument Panel Cluster Special Functions Mode. Then go to WOW mode, in this mode you can turn all the indicators ON and OFF.

    • ABS Indicator
    • TRAC OFF indicator
    • LOW TRAC indicator
    • Brake Warning indicator
    • Low Tire Warning indicator

The WOW Test aids in diagnosing indicator malfunctions. The test allows the operator to flash the all the indicators on and off manually.

Automated Test

The Automated Test cycles each valve solenoid and the pump motor to check component operation. If a malfunction is detected, the EBCM/EBTCM will set DTC(s), which will be displayed upon completion of the test. Perform the test as follows:

  1. Ignition OFF.
  2. Install the scan tool.
  3. Turn ignition to RUN, engine off.
  4. Select the scan tool's Special Functions.
  5. Select the Automated Test.
  6. Run the Automated Test.
  7. Note any DTCs set.

Solenoid Tests (Inlet Valves)

The Solenoid Test for inlet valves activates the selected wheel circuit Inlet valve placing it in the pressure hold position. When 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 ABS operating conditions because the EBCM/EBTCM has determined that the wheel is moving too slowly, so it holds additional master cylinder pressure from it in an attempt to allow it to rotate at an appropriate speed. The scan tool commands the valve to close, which should allow the technician to spin the wheel even though an assistant is applying pressure to the brake pedal. Perform the test as follows:

  1. Ignition OFF.
  2. Install the scan tool.
  3. Turn ignition to RUN, engine off.
  4. Raise vehicle such that wheels are about 6 inches off the floor with the transmission in neutral. Refer to Lifting and Jacking the Vehicle
  5. in General Information for lifting.

  6. Select the scan tool's Special Functions.
  7. Select Solenoid Test. Have an assistant command Hold Pressure with the scan tool.
  8. Have the assistant press and hold the brake pedal.
  9. Attempt to move the wheel being tested by hand; it should move even though the assistant is applying pressure to the brake pedal. The wheels may be difficult to turn by hand, but can be moved if the system is working properly.

Solenoid Tests (Outlet Valves)

The Solenoid Test for outlet valves activates the selected hydraulic wheel circuit valves, placing them in the pressure release position. When in the pressure release position, the valve will allow wheel caliper pressure to be returned to the master cylinder circuit. This is done under ABS 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 test as follows:

  1. Ignition OFF.
  2. Install the scan tool.
  3. Turn ignition to RUN, engine off.
  4. Raise vehicle such that wheels are about 6 inches off the floor with the transmission in neutral. Refer to Lifting and Jacking the Vehicle in General Information for lifting.
  5. Have an assistant press and hold the brake pedal.
  6. Select the scan tools Special Functions.
  7. Select Solenoid Test. Have the assistant command Release Pressure with the scan tool.
  8. Attempt to move the wheel being tested by hand; it should move even though the assistant is applying pressure to the brake pedal. The wheels may be difficult to turn by hand, but can be moved if the system is working properly.