LS1LT1 Forum banner

1 - 19 of 19 Posts

·
Registered
Joined
·
25 Posts
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. :)
 

·
Global Moderator
Joined
·
13,305 Posts
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.
 

·
Registered
Joined
·
25 Posts
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.
 

·
Global Moderator
Joined
·
13,305 Posts
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
 

·
Registered
Joined
·
25 Posts
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.
 

·
Registered
Joined
·
25 Posts
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.
 

·
Registered
Joined
·
25 Posts
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?
 

·
Registered
Joined
·
25 Posts
Discussion Starter #10
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.
 

·
Registered
Joined
·
25 Posts
Discussion Starter #12 (Edited)
Forgot to follow up with this post. Abs inop light is still on. All connections check out. i cleaned each connector that has to do with the abs system. Gounds are all good. Tried replacing the abs computer as that is what the manual said to do. That didnt work. Took out all my LEDs exept for the interior dome lights, fog lights, license plate light, transmission light, glove box light, front and rear side markers and popup lights. Cant imagine these would have anything to do with the abs system and changing its voltage but it might. None are in the instrument cluster anymore. Abs system passed all the scan tools tests. Tested each wheel speed sensor and each have the correct voltage and all read the same speed.

One thing i did notice was that on my 3rd break light, one of the bulbs sometimes doesn't turn on when i turn on my parking lights and also sometimes dosnt turn on when i press the brake pedal at all. If i move the bulb around it turns on but the abs light still says on when i do fix it. After i wiggle it around it dosnt seem to fix it from turning off. Could somthing be wrong with my wire for the 3rd brake light and it is causing my abs inop light problem? Reminder, the abs light dosnt turn on when the key is set to run position. It passes that check. It only turns on when i start the car.
 

·
Registered
Joined
·
25 Posts
Discussion Starter #14 (Edited)
Yes, problem with 3rd brake light can be caused by socket, wiring, connectors, & grounds.
Do you know where the wire goes for the 3rd break light? I see it goes way down into the spoiler but from there were does that lead? Want to see if it is damaged. Also how do i go about getting to the wire in the spoiler? Do i somehow have to remove the top of the spoiler to get to the wire?

The sockets that the bulbs go into are in pretty good shape if i remember so i dont think its the sockets. I put bulb contact grease on each bulb to make sure they were getting a good connection from the socket and sprayed the sockets with electric cleaner. All grounds look really good. Wires that go to each ground look good and the grounds are tight. So i dont think it is a ground or socket problem.
 

·
Global Moderator
Joined
·
13,305 Posts
I've never traced the 3rd brake light wiring. But you need to look at the back of hatch area when lid is raised. You should be able to find the wireing where it goes into the body.

If wires need to be changed, this electrician trick will help you. Tie a piece of strong string to end of wires at 3rd brake light. Make sure you have enough string to go all the way through hatch, with some extra.

When you pull wires through hatch, string will come with them. Attach new wires to string, which if you have enough string, will be hanging out at 3rd brake light end. You use the string at the 3rd brake light end to pull new wiring back to 3rd brake light.
 

·
Registered
Joined
·
25 Posts
Discussion Starter #16
I've never traced the 3rd brake light wiring. But you need to look at the back of hatch area when lid is raised. You should be able to find the wireing where it goes into the body.

If wires need to be changed, this electrician trick will help you. Tie a piece of strong string to end of wires at 3rd brake light. Make sure you have enough string to go all the way through hatch, with some extra.

When you pull wires through hatch, string will come with them. Attach new wires to string, which if you have enough string, will be hanging out at 3rd brake light end. You use the string at the 3rd brake light end to pull new wiring back to 3rd brake light.
ok, got it. Thank you very much. I will take a look at the wires hopefully soon.
 

·
Registered
Joined
·
9 Posts
If you have changed the bulbs to LED's, that could be your problem. LED's in the third brake light will sometimes cause ABS problems.
 

·
Registered
Joined
·
25 Posts
Discussion Starter #18
Yea, no leds in the 3rd brake light. The abs light turned off for the first time in months yesterday. Continued to stay off after i started the car a couple of times and both bulbs in the 3rd brake light seemed to be on. Ill see if the light turns back on when i run it again and if it does turn back on i will see if both bulbs are lit up on the 3rd brake light.
 

·
Registered
Joined
·
25 Posts
Discussion Starter #19
So far it hasn't turned back on. Hoping it stays that way. Only thing that was diffrent than every other day the light was on was that it got cold out and rained a lot. Not sure if that could tie into the issue im having or if its just coincidence.
 
1 - 19 of 19 Posts
Top