Fault code 31

The ABS carries out a self-test when the ignition is switched on. If no faults are found the light will go out. If the light stays on it means a fault has been discovered, recorded and the ABS will be switched off.

To rectify this condition the fault will have to be identified by a code read, the fault repaired and the fault code erased.

That would be a code 31, You can call your local dealership and the should be able to interpret this code for you

Error logs are a great thing. They will help you find intermittent problems and start you off in a general direction of where a problem could be. There is a great level of detail on the justcommodores site on checking error codes logged by the engine management system, but this does not detail anything about the abs system. The abs warning light is not as common as the check engine warning light. Reading through the posts, I haven't found any detail on checking error codes logged by the abs system.

So here it is. For those of you familiar with checking the engine error codes, this procedure is so simple its not funny.

Basically, to check the engine error log, you bridge the 5th (ground) and 6th pins in the ODB connector under the steering wheel.

To check the ABS error log, using the same trusty calibrated paper clip, you simply bridge pins 5 and 12 of the connector.

To find pins 5 and 12, start at the top left hand corner. That is pin one. Going to the right, you count pin 2,3,4 etc. Once you get to the end, jump back to the start of the bottom left level of pins and keep counting. Pin 5 is about halfway along the top row, pin 12 is a little left of the middle in the bottom row.

Reading the error codes is the same procedure (counting the flashes), except now, the ABS light flashes (as opposed to the engine light when checking the engine codes).

The ABS log also uses code 12 firstly, with any errors logged shown after that. If no errors are logged, the 12 will flash again.

Error codes for the ABS error log (VR/VS) are as follows:

12 Diagnostic system operational
21 Right hand front wheel speed sensor fault
23 Right hand front wheel speed sensor continuity fault
25 Left hand front wheel speed sensor fault
27 Left hand front wheel speed sensor continuity fault
28 Wheel speed sensor frequency error
31 Right hand rear wheel speed sensor fault
33 Right hand rear wheel speed sensor continuity fault
35 Left hand rear wheel speed sensor fault
37 Left hand rear wheel speed sensor continuity fault
41 Right hand front inlet solenoid valve circuit fault
42 Right hand front outlet solenoid valve circuit fault
45 Left hand front inlet solenoid valve circuit fault
46 Left hand front outlet solenoid valve circuit fault
55 Rear inlet solenoid valve circuit fault
56 Rear outlet solenoid valve circuit fault
61 Pump motor relay circuit fault
63 Valve relay circuit fault
71 ABS control module internal fault

The above guide has been verified on a VR/VS. Checking the error log on all models prior to VR/VS is the same for the engine log, and I would assume that the same can be said for the ABS log, would be happy if someone could verify this for me.

What do you want to know?

Any type of light on your dash is an
OBD System Failure or at least you check for a fault
code & diagnose

These type of lights have been on all vehicles since1980
That is 31 years,a long time

You have an owners manual or order one from Helm.Com

ABS is part of your braking system, if that is what your asking

Any light will stay on your dash, until you repair the vehicle
That is why they light up

You obviously have an OBD2 (ABS) System Malfunction

Why you ask the question, I have no idea, you need as
we all have for the last 31 years ,when we get any light on the
dash & there never has been a light called an idiot light,
their there for a reason.

Check for codes
Diagnose System with fault
Repair

You do the same thing that everyone should have been doing
since 1980,some 31 years now

Check for codes ---anytime you get ANY malfunction
indicator lamp on your dash

Diagnose the system with the fault


Repair

Could be a Wheel Speed Sensor
Has to be checked out,can't guess

Never heard of OBD2 (On-Board-Diagnostics)

Have been on all vehicles for 31 years

CHECK LIGHT ON DASH (ABS)

Check for codes
Diagnose system with problem
Repair

Abs ---is a system with many items that could go wrong

ABS Fault Code List 1991 Corvette (C4)
Code Definition
21 Right Front Wheel Speed Sensor Fault
22 Right Front Toothed Wheel Frequency Error
25 Left Front Wheel Speed Sensor Fault
26 Left Front Toothed Wheel Frequency Error
31 Right Rear Wheel Speed Sensor Fault
32 Right Rear Toothed Wheel Frequency Error
35 Left Rear Wheel Speed Sensor Fault
36 Left Rear Toothed Wheel Frequency Error
41 Right Front Solenoid Valve Fault
45 Left Front Solenoid Valve Fault
55 Rear Wheels Solenoid Valve Fault
61 Pump Motor or Motor Relay Fault
63 Solenoid Valve Relay Fault
71 Electronic Brake Control Module Fault
72 Serial Data Line Fault
75 Lateral Accelerometer Fault (Short ot Open)
76 Lateral Accelerometer Fault (Signal out of Range)

31 is throttle position sensor, 42 is Idle switch

CODE 32- FRONT LEFT WHEEL SPEED SENSOR SIGNAL MALFUNCTION. CODE 31- FRONT RIGHT WHEEL SPEED SENSOR SIGNAL MALFUNCTION. CODE 48- OPEN OR SHORT CIRCUIT IN VTA2 SIGNAL CIRCUIT OF THE SUB THROTTLE POSITION SENSOR.