For 1990-2009 cars

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 EBCM/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

• | 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 EBCM/EBTCM can be cleared.

#### Data Display

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

• | Data Display (ABS)

• | Data Display (TCS)

A brief description of all ABS/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.

- | Rear Wheel Speed--scan tool displays: Km/h / MPH--Display shows actual wheel speed.

- | 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 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.

- | Throttle Angle--scan tool displays in percent of throttle open.

- | Brake Switch--scan tool displays: Applied/Released--This parameter indicates the state of the brake switch.

- | TCS Switch State--scan tool displays: On/Off--This parameter indicates the state of the traction control 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.

- | Vehicle Speed--scan tool displays: Km/h / MPH--Display shows actual vehicle speed.

- | 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 TCS On/Off switch, or if the TCS is disabled because of a malfunction.

- | 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 can 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 Tests

- | ABS Warning Lamp

- | Low Trac Lamp

• | TCS

- | TCS Test

- | Lamp Tests--TCS OFF Lamp (ASR if vehicle is a Chevrolet)

- | TP Sensor Replacement

The Special Functions are detailed below.

### 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 EBCM/EBTCM will set DTCs, 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 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.
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 Valve 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 Tests for the outlet valves activates the selected hydraulic wheel circuit 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 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.
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 Valve 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 appropriate solenoid valves to apply fluid pressure to the rear 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 rear wheel by hand, they should not move, due to the pump motor running and applying pressure to the rear wheels.

### TP Sensor Replacement

This procedure must be run anytime the TP sensor is replaced on a vehicle that has Traction Control (RPO NW9). The TP sensor replacement allows the Accelerator and Servo Control Module (ASM) to relearn the new TP sensor position.

1. Ignition OFF.
2. Install the scan tool.
3. Turn ignition to RUN.
4. Select the scan tools Special Functions.
5. Select TP Sensor Replacement.
6. Follow the scan tool menus until the procedure is completed.