Service ASR light

[weatherman]

I have a '92 LT1 and the service ASR light has been on for some time, and yes the brake fluid reservoir is completely full. Because my regular mechanic's scanner couldn't initially dig deep enough into my ECM to narrow down the problem, I dropped $100 at the local Chevy dealership for a diagnosis, and they said the TPS (throttle position sensor) needed to be replaced. I replaced the TPS, and the service ASR light remained lit. Took it back to my regular mechanic, he put it back on the scanner, and it is now showing error code #28 which supposedly translates to Quad-Driver Module #3 Circuit. Can anyone please tell me what that really means? Is it a problem that be individually resolved within the ECM, or will I more than likely have to replace the whole thing? Lastly, if I do need to replace the ECM, anybody got any suggestions who or where to order it from? Thanks. Sorry for being so windy.

 

[93Rubie]

The ASR is not ECM controlled. The ASR/ABS is self controlled but it does give inputs and receives data from the ECM. However, if you ASR light is on you will not find codes in the ECM for the ASR. It is a separate system. Any codes like a throttle position code or quad driver code are NOT for the ASR, those are ECM codes.

If you mechanic did a get a code 28 for the ASR it would be a Wheel Speed Sensor Frequency Error code. My info is correct for a 93 as per my FSM. (Field Service Manual, if you do not have one, get one, worth its weight in gold, and apparently that dealership does not know how to use one or a Tech1A or Tech II scan tool. The FSM's can be found on E-bay or Zip Corvette or Corvette Central, etc....only buy the Red Ones.) On my scan tool the ABS/ASR is seperate from the ECM on the scan tools screen as far as selection of modules is concerned. I have a OTC Nemisys updated thru 07 Domestic. This might not help you, but your mechanic, it might.

Is there any Check Engine Light on? How does the car run?

FYI, you can access ASR/ABS codes via the CCM and instrument cluster interface using the Trip/Fuel buttons. This procedure is found in the FSM, you might find it here doing a search.

I would say with no other lights the problem is in the ASR system, you need to pull the code for the ASR and start from there. A decent scan tool or the above CCM method will work. I would check any relevant fuses as well.

 

[Hib Halverson]

I have a '92 LT1 and the service ASR light has been on for some time, and yes the brake fluid reservoir is completely full. Because my regular mechanic's scanner couldn't initially dig deep enough into my ECM to narrow down the problem, I dropped $100 at the local Chevy dealership for a diagnosis, and they said the TPS (throttle position sensor) needed to be replaced. I replaced the TPS, and the service ASR light remained lit. Took it back to my regular mechanic, he put it back on the scanner, and it is now showing error code #28 which supposedly translates to Quad-Driver Module #3 Circuit. Can anyone please tell me what that really means? Is it a problem that be individually resolved within the ECM, or will I more than likely have to replace the whole thing? Lastly, if I do need to replace the ECM, anybody got any suggestions who or where to order it from? Thanks. Sorry for being so windy.

After you replaced the TPS did you clear codes?

Code 28 is not an ASR fault but an engine controls fault. Quad drivers are devices used to control various engine controls functions. They are called that because each quad driver module, there are two, I believe, has four drivers. Quad drivers are not in the ECM, thus if you replace the engine controller, the quad driver fault will still exist.

If you are going to continue to work on this DIY, you need the Factory Service Manual so you can 1) learn how to read ABS/ASR codes and engine codes and 2) have the troubleshooting information for both ABS/ASR faults and ECM faults.

 

[weatherman]

93rubie. the car runs fantastic. I just can't get the 'service asr' light to go out. there are no other idiot lights lit. so based on the fact that the 'service asr' light is on and it is throwing a code 28, you think it may have a faulty wheel speed sensor? I really do need to get a FSM. thanks.

 

[Robertwav1]

I have a '92 LT1 and the service ASR light has been on for some time, and yes the brake fluid reservoir is completely full. Because my regular mechanic's scanner couldn't initially dig deep enough into my ECM to narrow down the problem, I dropped $100 at the local Chevy dealership for a diagnosis, and they said the TPS (throttle position sensor) needed to be replaced. I replaced the TPS, and the service ASR light remained lit. Took it back to my regular mechanic, he put it back on the scanner, and it is now showing error code #28 which supposedly translates to Quad-Driver Module #3 Circuit. Can anyone please tell me what that really means? Is it a problem that be individually resolved within the ECM, or will I more than likely have to replace the whole thing? Lastly, if I do need to replace the ECM, anybody got any suggestions who or where to order it from? Thanks. Sorry for being so windy.

Just a thought...I know you said the brake fluid res is full but is the sensor working?

 

[93Rubie]

Just a thought...I know you said the brake fluid res is full but is the sensor working?

If the sensor was faulty (reading low for no reason) the RED brake light SHOULD be on as well, at least one would think so.

Weatherman, based on what you said, sounds like a ASR only problem. Code 28 is not necessarily a bad wheel speed sensor but it could be. The 93 FSM calls it a Wheel Speed Sensor Frequency Error. You are going to need a FSM for this one, no way around it. You may also want to find someone with a ABS/ASR capable scan tool, this would help a ton. Best of Luck.

 

[gmjunkie]

If the sensor was faulty (reading low for no reason) the RED brake light SHOULD be on as well, at least one would think so.

Weatherman, based on what you said, sounds like a ASR only problem. Code 28 is not necessarily a bad wheel speed sensor but it could be. The 93 FSM calls it a Wheel Speed Sensor Frequency Error. You are going to need a FSM for this one, no way around it. You may also want to find someone with a ABS/ASR capable scan tool, this would help a ton. Best of Luck.

A lot of times the rear wheel sensor reluctor rings on C4's get covered with brake dust with metallic particles and the sensor will mis-count the teeth on the ring!~!! First thing I'd do is check and clean the rear rings,their open on the backside so usually their purdy cruddy!

 

[Hib Halverson]

As is often the case "gmjunkie" is on the right track.

I wasted bandwidth talking about Quad drivers when it was obvious---if I'd read the post carefully--that the mechanic read the ABS/ASR code 28 and the OP interpreted it using the ECM code, ie: DTC28 Quad driver fault. Well...duh! Silly me.

ASR code 28 is, of course, wheel speed sensor error and the advice "gmjunkie" dispensed...check the ABS wheels for dirt and stuff is spot on.

If you clean the dirt off, clear codes then have the code reset, you'll need the FSM and a scan tester with ABS/ASR software to solve the code.

 

[CHRLDO]

i had the same problem on my 92 , it was the front speed sensor connector. i forgot to reconnect after removing inner panels to do plugs and wires. the wire goes from front wheel hub thru opening in inner wheel well and is plugged into a connector after it passes thru the opening. connector is fastened to the rear section of the 3 pc. inner fender well . might be loose or might need cleaned .

 

[9340Ruby]

93rubie. the car runs fantastic. I just can't get the 'service asr' light to go out. there are no other idiot lights lit. so based on the fact that the 'service asr' light is on and it is throwing a code 28, you think it may have a faulty wheel speed sensor? I really do need to get a FSM. thanks.

I had the same code and had the ASR service light on as well. The car ran perfect for a long time. I did not want to just through parts at it. After approximately several months of the ASR light on, my car ran perfect but would not restart when hot. The injectors were not spraying, the engine was just cranking over, so look out for that possibly happening to you. I did several tests and finally put a bag of ice on the ECM when hot and it would immediately start up. I sent my ECM off to directauto.com and for $163.00 they repaired it and sent it back overnight mail. It has worked flawlessly ever since. I hope you figure out your problem too.

 

[digimc]

I know this is an old thread but we have old cars. I had the dreaded ASR light for several months. The light would come on after I started the engine and moved forward at about 10 mph, and stay illuminated until the next cycle. The only indication was the lighted ASR, no other symptoms. The first thing I checked was the ASR motor and pulley. No problem there. Next, I pulled the rear wheel sensors and found that they were coated with grime, metallic fines and road dirt. I cleaned them with a dry napkin and my fingernail. That cured the issue. This car has only 23000 miles and is never driven in inclement weather (only if it's 72+ deg and the top can be down) so I imagine that normal usage would cause this issue in a very short time. Hope this helps others as an easy first check.

UPDATE: Shortly after posting this the problem again became intermittent. Some days I can put 50 miles without the ASR light illuminating and other days it comes on from the start of the trip. I guess I live with it. In the end, should I keep the car long enough, I will probably be deleting the entire system (ASR, ABS). The costs involved for the control modules at are not worth it - not to mention that the ASR module can't be repaired and NOS is a gazillion $$$ if you could find it. I don't drive in rain or snow so the benefits are minimal. Resale would be the only consideration.

 

[DonB]

Hi guys. I think gmjunkie hit the "nail on the head" here. I recently replaced my rear wheel bearings(and most of the rear suspension) and you wouldn't believe the crud built up on the wheel speed reluctor rings and the sensor.

They get coated with rust, brake dust, grease and God knows what else. With that housing open on the inside, where the half-shaft connects, it slings all kinds of stuff in there. I wire brushed mine off real good while I had it apart. I'd think some Brake-Kleen and a good blow off would do the trick to clean it while assembled. There's very little room in there with the suspension installed. Although that's pretty much the "status quo" for the whole car!.....LOL!