GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 1998 🢒 Grand Prix 🢒 Brakes 🢒 Antilock Brake System 🢒 Scan Tool Diagnostics

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 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
      • ETC/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 can be cleared.

Data Display

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

    • Data Display (ABS/ETS)
    • Data Display (ABS/ETS/MSVA)
    • Data Display (ABS/TCS/MSVA)

A brief description of all ABS/ETS/TCS data parameters available on the scan tool are listed below:

    • ABS Data:
      • Left Front Wheel Speed--scan tool displays: Km/h / MPH--Display shows actual wheel speed.
      • Right Front Wheel Speed--scan tool displays: Km/h / MPH--Display shows actual wheel speed.
      • Left Rear Wheel Speed--scan tool displays: Km/h / MPH--Display shows actual wheel speed.
      • Right Rear Wheel Speed--scan tool displays: Km/h / MPH--Display shows actual wheel speed.
      • Engine Speed--scan tool displays: 0 to 10200 RPM--This is essentially a digital tachometer display.
      • Brake Switch--scan tool displays: Applied/Released--This parameter indicates the state of the brake switch.
      • Valve Relay State--scan tool displays: On/Off--This parameter indicates the state of the valve relay.
      • Pump Monitor State--scan tool displays: On/Off--This parameter indicates the state of the return pump relay.
      • TCS Switch State--scan tool displays: On/Off--This parameter indicates the state of the traction control switch.
    • ETS Data:
      • Engine Speed--scan tool displays: 0 to 10200 RPM--This is essentially a digital tachometer display.
      • Vehicle Speed--scan tool displays: Km/h / MPH--Display shows actual vehicle speed.
      • EBTCM to PCM Requested Torque--scan tool displays: -100 to 510N·m--This parameter represents the requested engine torque from the EBCTM to the PCM.
      • PCM to EBTCM Delivered Torque--scan tool displays: -100 to 510N·m--This parameter represents the delivered engine torque from the PCM to the EBTCM.
      • PCM Torque Reduction--scan tool displays: Active/Inactive--This parameter indicates whether the PCM is actively reducing engine torque.
      • PCM Inhibit of ETS--scan tool displays: Yes/No--This parameter indicates if the PCM is temporally inhibiting ETS because of high catalytic converter temperature or the engine coolant temperature is outside the normal range.
      • ETS Status EBTCM--scan tool displays: Inable/Disable-- This parameter indicates the state of the ETS based on if the operator has disabled ETC by pressing the TRAC switch, or if the ETS is disabled because of a malfunction.
      • ETS Status PCM--scan tool displays: Inable/Disable--This parameter indicates if the PCM is permanently inhibiting ETC because the PCM has set a DTC(s) that turns on the CHECK ENGINE indicator.
      • ETS State EBTCM--scan tool displays: Active/Inactive--This parameter indicates if the ETS is currently in a ETS event or not.
    • TCS Data:
      • Engine Speed--scan tool displays: 0 to 10200 RPM--This is essentially a digital tachometer display.
      • Vehicle Speed--scan tool displays: Km/h / MPH--Display shows actual vehicle speed.
      • EBTCM to PCM Requested Torque--scan tool displays: -100 to 510N·m--This parameter represents the requested engine torque from the EBCTM to the PCM.
      • PCM to EBTCM Delivered Torque--scan tool displays: -100 to 510N·m--This parameter represents the delivered engine torque from the PCM to the EBTCM.
      • PCM Torque Reduction--scan tool displays: -Active/Inactive--This parameter indicates whether the PCM is actively reducing engine torque.
      • PCM Inhibit of TCS--scan tool displays: Yes/No--This parameter indicates if the PCM is temporarily inhibiting TCS because of high catalytic converter temperature or the engine coolant temperature is outside the normal range.
      • TCS Status EBTCM--scan tool displays: Inable/Disable-- This parameter indicates the state of the TCS based on if the operator has disabled TCS by pressing the TRAC switch, or if the TCS is disabled because of a malfunction.
      • TCS Status PCM--scan tool displays: Inable/Disable--This parameter indicates if the PCM is permanently inhibiting TCS because the PCM has set a DTC(s) that turns on the CHECK ENGINE indicator.
      • TCS State EBTCM--scan tool displays: Active/Inactive--This parameter indicates if the TCS is currently in a TCS event or not.

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 grouped as following:

    • ABS
      • Automated Test
      • Solenoid Tests (for all inlet and outlet solenoid valves)
      • Lamp Test (ABS indicator)
    • TCS
      • TCS Test
      • Lamp Tests
   • TCS OFF indicator
   • LOW TRAC indicator

In a vehicle equipped with ABS/ETS, the Special Functions are as follows:

    • Automated Test
    • Solenoid Tests (for all inlet and outlet solenoid valves)
    • Lamp Tests
      • ABS Indicator
      • LOW TRAC indicator

The Special Functions are detailed below.

Lamp Test

This test allows activation of the following indicators:

    • ABS Indicator
    • ETS/Trac off indicator
    • Low Trac indicator

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

Automated Test

The Automated Test cycles each valve solenoid and the pump motor (as well as the necessary relays) to check component operation. If a malfunction is detected, the 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.
  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 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.
  4. Raise vehicle such that wheels are about 6 inches off the floor with the transmission in neutral.
  5. Select the scan tool's Special Functions.
  6. Select Solenoid Test. Have an assistant command Hold Pressure with the scan tool.
  7. Have the assistant press and hold the brake pedal.
  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.

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 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.
  4. Raise vehicle such that wheels are about 6 inches off the floor with the transmission in neutral.
  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.

Traction Control System Test

This test runs the pump motor and the applicable solenoid valves to apply fluid pressure to the front wheel circuits.

Perform the test as follows (this test does not require an assistant):

  1. Ignition OFF.
  2. Install the scan tool.
  3. Turn ignition to RUN.
  4. Raise vehicle so that wheels are about 6 inches off the floor with the transmission in neutral.
  5. Select the scan tools Special Functions.
  6. Select TCS Test.
  7. Command the TCS Test on with the scan tool. The pump motor will turn on for approximately 25 seconds.
  8. Attempt to move each front wheel by hand, they should not move, due to the pump motor running and applying pressure to the front wheels.