Toyota Repair: 1994 Prizm ABS light on / ABS active light sometimes flashes on start-up

Question
QUESTION: This is on my 1994 Prizm LSI (Corolla clone) with 342,000 miles.

With the advent of colder and damp weather, my ABS system is acting up.  When I start the car, the yellow "ABS" stays on normally the whole time the car is running.  Sometimes, the white "ABS Active" flashes rapidily in synchronization with clicking sound from under the hood (coming from the ABS module on the right front corner of the engine compartment).

This clicking and "ABS Active" flashing usually lasts less than a minute after start-up, but the ABS light stays on.  Rarely, the "ABS Active" and clicking is accompanied by the red "Brake" warning light flashing at the same frequency.  

I assume that the ABS light stays lit because some kind of a code is set in the ABS computer, but I have no idea how to read it.  Could this be a bad ground on the ABS system, or more likely a wheeel sensor gone bad??

Thanks for any ideas or things to look at.


obd connector   ANSWER: My best guess and the most common problem is a wheel speed sensor, check the brake fluid first, this being a 1994 it could have either the old OBD 1 or the newer OBD 2 diagnostic system, I heed to know if there is a check connector to the left of the steering wheel, or you can look under the hood at the label, it will indicate if it is OBD 2 compliant, after that I can show you how to check for codes.  

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QUESTION: Brake fluid is OK.  I did check that.  It is an OBD I car with the test ports under the hood.  But, my understanding is that ABS codes are not available on the Prizm OBD I set-up.  Thanks.

Answer
Toyota Corolla ABS service - Helpful Tech Tips From Car ...
Copy this link into your browser and click on the top link of the same name, there is all the information you need to check for codes and well as code definitions, after that let me know the results and we can continue from there.