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Discussion Starter #1
Hi, i have a 1993 trans am and it has had an abs inop light on for about a couple of months. Before the abs inop light would turn off and on once in a while but it seems to have gotten much worse over time. I bought a Chinese tech 2 scan tool and scaned for codes on the abs system. I had no codes come up at all. The scan tool shows that the speed sensors on the car are accurate since each sensor reads the exact same speed as my speedometer is reading. I cleaned each sensor and put dye electric grease in them and cleaned the sensors with some electric cleaner. I did switch my entire car to LEDs on the exterior besides the blinkers in the front. I have had a couple issues of using LEDs as the car wants to check for a certain voltage and since the LEDs produce less power and volts than the incandescent bulbs do it sets dash lights off. I havnt tried putting back incandecent bulbs in the 3rd tail light but i will soon because it may think the tail light is out because im using LEDs in the 3rd tail light (even tho it isnt burnt out). Also, the abs inop light turns on for 3 seconds and off like normal when i turn on the car but not start it. And i can flash the light and manualy turn it on too with the tech 2. What is interesting is when i look at the abs system in the tech 2 while driving, it says the abs inop light isnt even on!!! I have read just about every forum there is on the abs inop light and am out if ideas. Lastly, the cuise control stopped working when the abs light is on. Not sure if thats tied into the abs system or not. Any help would be appreciated as the struggles are real here lol. :)
 

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If your using led bulbs in 3rd brake light, that might be your problem. ABS light will come on when 3rd brake light is out. Computer sees led bulb as being out.

People fix led light problem by either switching back to regular bulbs or adding resistor to wiring going to led bulb of 3rd brake light. Sorry I can't tell you how many ohms resistance you should use. But I guess a resistor that can handle at least 2 or 3 watts is needed.

You can do a web search to find the proper ohms resistance needed.
 

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Discussion Starter #4 (Edited)
Didnt work sadly. I put incandecent bulbs in and started car and light was still on. It went off once after i changed the bulbs after a couple hours later of letting it sit and not driving it. However, when i started it again the next day, it turned back on Which it had just rained in the night. The interesting thing is though is the light likes to come and stay on after it just rained. When ever the light decides to go off, it always comes back on when water gets on the car. I had washed the car a couple times and the light for abs inop comes on after word. When the light decides to turn off, all is good until it rains. ( most of the time it seems) Super frustrating.
 

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You might want to check the connectors of the ABS system to see if any of them look like water has gotten in. Nothing like good old water to cause a short in the wiring.

And while your checking connectors, look for bent pins,corrosion, wires that look like they've been overheated etc.

Here's a link to 93 factory servive manual to help you chase wires down. www.mediafire.com/?40mfgeoe4ctti
 

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Discussion Starter #7
been doing a lot of reading on all other forums too on people having the abs inop light. I made sure that all my bulbs on the dash are back to incandescent ones. Im going to check wires later today if i get time to do it. Its weird though how my tech 2 scan tool says the light is off when it is clearly on on my dash.
 

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Discussion Starter #8 (Edited)
i am just confused on why the scan tool is saying the light is off and it isnt detecting anything wrong with it. i can make the abs light turn on and off rapidly and make it solid with the scan tool both not starting car and starting car so i would assume that would mean its communicating with the abs system. One forum said to replace the abs fuse, another said check the reluctor ring in the rear end, and another said replace EBCM. Seems like its all over the place. Having the scan tool saying nothing is wrong though is defying logic here. And i cant use cruise control until i get this darn light to turn off.
 

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Discussion Starter #9
So i thought of an idea, i have leds in my tail lights, but not my 3rd break light. Would that trigger the abs inop light?
 

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So i have checked so far every wire and have done almost all testes on abs system With scan tool and all pass. I have cleaned all sensors on every wheel speed sensor and around them. So far nothing i have done has had any change on turning off the abs inop light. Only test i havnt done is a motor test on the scan tool. After i have done that, everything regarding the abs system i have done (that i can think of). Any help at all at this point would be very much appreciated. Might have to see a mechanic on this.
 

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Discussion Starter #11 (Edited)
So i checked history codes on my scan tool and there is a code for c1211 which is C1211 - ABS Indicator Lamp Circuit Malfunction

Read more at: https://www.obd-code...assis-codes.php
Copyright OBD-Codes.com

i also found multiple websites saying ABS Outlet Valve Coil RF Circuit Open. Im not exactly sure what this means. The code dosnt show up in my manuel so im not sure what this code means.

I also ended up finding a missing seal around my right front speed sensor so i think water must have gotten in there, causing the abs inop light to turn on when it rains. How ever it hasnt rained for a while so im still not sure why its still on. Code was also triggered at 0 mph and it has happened 9 times according to the scan tool.
 
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