Diagnostics

 

CEL Intake Manifold
Do It Yourself: Diagnostics  
Anti-Lock Brake System Test
Automatic Transaxle Self Test
Engine Self Test
Intake Manifold Vacuum Test
Variable Assist Power Steering Test
Supplemental Restraint System Test
 
Anti-Lock Brake System Test: 1989-91 Probes [
Overview Probes equipped with anti-lock brake systems have an internal diagnostic system. When the engine is started, the ABS warning lamp on the instrument cluster should illuminate for a second or two, and then go out. If the lamp stays illuminated after the engine is started or illuminates while driving, there may be a problem with the anti-lock brake system. Checking for error codes is an easy way to find out what's wrong and what, if anything, caused the ABS warning lamp to illuminate.

Procedure Checking for codes can be performed with a standard analog voltmeter. Set the meter to read between 0 and 20 volts.

There are two types of error codes:

Present Error Code
An ABS warning lamp that stays illuminated indicates that there is a present failure.

Continuous Error Code
A flashing ABS warning lamp indicates a continuous error code. This type of occurance is for intermittent faults where a fault code was generated at one point, but is no longer present.

Remove the driver's seat. Find the four-wire connector on the ABS control module. Without disconnecting the connector, connect a jumper wire between the check terminal wire (Green/Black) and the ground wire (Black).
 

Connect the positive wire of the voltmeter to the Green/Red wire on the ABS control module connector. Connect the negative wire on the voltmeter to a ground.
 

When you're ready to start the test, start the engine. If a continuous error code is present, it may be necessary to drive the vehicle to try to re-create the fault event.

See below for how to interpret the pulses.

Interpreting the Codes The pulses on the voltmeter translate into single digit codes. Every time the needle on the voltmeter sweeps across to 12 volts and drops back to zero, that is considered one pulse. Codes are displayed by the number of pulses the voltmeter displays. So three pulses would indicate an error code 3. If there is more then one error code, they are separated by a longer pause.

 

Code 3

In addition to the voltmeter, you will need to keep an eye on the ABS warning lamp during the test as well. The lamp will either flash on then off once for each code, or will stay illuminated. A flash or a continuous illumination of the ABS warning lamp will be part of determining which fault is present.

Clearing the Codes At the ABS control module connector, connect a jumper wire between the Green/Red wire and the Green/Black wire. Turn the ignition on. Check that the ABS warning lamp is illuminated and wait 1-2 seconds. Turn the ignition off and remove the jumper wire.
 

 

 
Anti-Lock Brake System Test: Codes  
Code ABS Lamp Sensor or System
1 Flash Wheel Brake Sensor, Wiring Harness, or Hydraulic Actuation Assembly - Right Front Wheel
2 Flash Wheel Brake Sensor, Wiring Harness, or Hydraulic Actuation Assembly - Left Front Wheel
3 Flash Wheel Brake Sensor, Wiring Harness, or Hydraulic Actuation Assembly - Rear Wheel
4 Flash Sensor Rotor - Right Front Wheel
Possibly caused by:
bulletDamaged sensor rotor
5 Flash Sensor Rotor - Left Front Wheel
Possibly caused by:
bulletDamaged sensor rotor
6 Flash Sensor Rotor - Right Rear Wheel
Possibly caused by:
bulletDamaged sensor rotor
7 Flash Sensor Rotor - Left Rear Wheel
Possibly caused by:
bulletDamaged sensor rotor
1 Illuminated Hydraulic Actuation Assembly Unit or Wiring Harness
Possibly caused by:
bulletDefective pump motor
bulletDefective pressure switch
bulletFaulty wiring harness
bulletPoor connection of ABS control module 11-pin connector module
2 Illuminated Hydraulic Pump Motor Relay, or Wiring Harness
Possibly caused by:
bulletDefective motor relay
bulletFaulty motor drive circuit wiring harness
3 Illuminated Hydraulic Pump Motor Relay, or Wiring Harness
Possibly caused by:
bulletDefective relay
bulletFaulty fail-safe ground circuit wiring harness
4 Illuminated Hydraulic Pump Motor Relay, or Wiring Harness
Possibly caused by:
bulletDefective relay
bulletFaulty drive circuit wiring harness
bulletFaulty motor drive circuit or ground circuit wiring harness
5 Illuminated ABS Control Module
Possibly caused by:
bulletDefective solenoid control valve
bulletDefective control module
6 Illuminated ABS Control Module
Possibly caused by:
bulletDefective control module
No Code Illuminated Other
Possibly caused by:
bulletPoor connection of ABS control module 17-pin connector
bulletInsufficient battery capacity
bulletLow alternator voltage output

 

 

 

 

Created by Scott Amoroso