Hi.

Back again with another problem I hope someone can help me with.
I have a 96 LT1 coupe I just finished doing some front suspension work and changing the plug and wires, during the course of this work I removed the front steering knuckle which required the disconnection of the speed sensor connections.

I also ran the car after I changed the plugs and wire and naturally received a Service ASR and Service ABS warning light because the sensors were disconnected at the time. The only other problem I had was during the course of this work the battery went dead so I had to charge it yesterday before I could drive the car. When I started the car I had no warning lights everything was normal but when I went to test drive it as soon as I reached some speed I got an ASR Active and I could hear it going then it presented some resistance at the gas pedal and went to Service ASR, Service ABS and ASR Off.

So far I have rechecked all the front connections and cleaned them with contact cleaner I have also disconnected the battery twice for upwards of 15 min. and checked my brake fluid level which is at the Max line.

Everything was fine before I did this any suggestions? Thanks in advance.

 

Try this link to see if you can pull the codes, with that information someone might be able to assist you but you really need a FSM.

http://www.corvettephotographs.com/c4vettes/codes.htm

 

Quite true. Did you have both front wheels sensors disconnected? Just a guess w/o codes but I'm thinking it's detecting a faulty or no signal from the front wheels, thus sensing wheelspin and reacting accordingly.

 

Just checked the codes and it shows an H21 & H23 which according to the FSM refers to the right front speed sensor, just checked ohms from terminals 22 & 23 on the EBTCM and read 1217 ohms, FSM calls for 990 to 1210 I would think 7 ohms would pass the test but it doesn't look like it.

Any help would be appreciated. Thanks Again

 

Any more ideas, I am open to suggestions on this one I really don't want to change the bearing assembly.
Thanks

 

I would follow the flow chart in the manual, I don't have a 96 FSM but my 93 says to check the sensor resistance at the sensor, have you done that as well as a good visual inspection for sensor damage? If resistance is closer to the correct value at the sensor I would then check the wiring from the sensor to EBTCM.

 

Find someone with a Tech-1A or Tech-2 scan-tool that has the software to diagnose ABS/ASR problems and it will tell you what is wrong.
With it, while driving down a straight road, you can see the individual speeds of each wheel speed sensor and the speedometer at the same time and compare them -- on a straight road they should all be the same.
It also allows you to do individual tests on each wheel.

Tom Piper

 

I've got a Tech 1 and Wellington isn't that far from Boynton Beach but don't know for sure if my mass storage cartridge has software that will read 96 ABS data, the version listed is 2.0 if anyone happens to know?
I do have the 12 pin to 16 pin adapter.

 

Thank you for the offer, sounds good. I have been following the FSM flow chart and everything checks out. The sensor is now reading 1117 ohms, no shorts between the sensor wires. No faults to ground on the sensor wires and no sign of any induced voltage interfering with the signal. According to the FSM the fix replace the wheel bearing/sensor assembly and if that doesn't clear the problem replace the EBTCM. So I quess I will be bearing shopping and EBTCM shopping. I am almost tempted to swap the front bearings and see if the code follows the assembly from the right to the left.

Thanks everyone for your help, this is one great resource provided by this forum.

 

PM me if you want to try the Tech 1 before you buy the new parts. It does have ABS software but I haven't tried it on a C4 with OBDII so can't swear it will work.
If it isn't ridiculously difficult to swap the bearings your plan seems sound to me, then you will know for sure, Good luck.

 

this may sound strange...but you worked on it so long the battery went dead...how long was that... could your gas have gone bad...I had ASR & ABS codes come up when I bought my car....the guy before me ran reg. unleaded gas...When I switched to premium the codes were gone.

Maybe since you played with the plugs and cables this may be a relayed issue...just a thought

 

I agree with you with the 7 ohms. The FSM has to give you some limits. There really looking for an open or a short. What really important is the signal coming back to the to the computer. That's what is really looked at which requires continuity all the way back to the brake computer including connections.

 

Thanks everyone

I went ahead and swapped the front bearings this morning and sure enough the code followed the sensor so I guess I am front bearing shopping to make this problem go away.

 

This is just off the cuff.
I have never had to do this myself, but have read where some have had luck cleaning out the assembly. I understand if to much dirt is in there, it may reduce or kill the signal. It is a magnetic pick up and I don’t know how much dirt and debris is to much that would make the difference.

Try some alcohol on the pickup or dedicate parts to clean it up. Then dry it with clean air. Who know, you might get lucky.

 

Thanks for the tip but unfortunately on a 96 the front sensor is a sealed assembly that is part of the bearing assembly. I have cleaned the connection several times and have checked the resistance from the EBTCM to the sensor, no problem I get the same resistance at EBTCM connector as on the sensor itself. Also checked for shorts, ground and induced voltages with no luck. I have to believe the wiring is good because when I swapped the front bearings the code followed the sensor which rules out the interconnecting wiring.
I will try driving it for a few days and see what happens if it doesn't clear then a bearing assembly replacement is in order.

Thanks
Kevin

 

I am a new member and owner, I just placed my thread a few days ago.
Listen, I have the same problem, but Mr.Mojo advised me that its beacuse of wrong tire sizes I have 235/55/R17 front, 255/55/R17 rear.
Could you tell me if each wheel should have sensor? Also, you ordrered bearing assmbly. Did you do some research? Where you buying it from?
Thanks
Batyrkhan

 

I don't know about tire size and effect but I would think because each wheel has a sensor as long as the tires were the same side to side it would not make a difference because the sensor just allows the electronics to determine a variation in RPM on each wheel.
I bought a new bearing assembly from Mid America and my problem is solved.
Let me know if you need any additional information.