Thread: Multiple ABS codes

I finally found the site again! I couldn't log in using my old info so I had to create another one.

My current issue is with the ABS system. The ABS lights are always on. The brake warning light will go on and reset when I turn the car off. I scanned the car and found 5 codes. This is for my '05 GTP.

C0040 - RF wheel speed sensor
C0036 - LF speed circuit range performance
C0450 - Steering assist control actuator
P0703 - Brake switch circuit low
U1040 - Lost communication with brake control module

I have searched the site and found solutions for them but my question is could the brake and speed sensors be symptoms and the EBCM be the cause? I have had the service power steering message for years and I know the rack needs replacing.

One last thing is I just had the transmission rebuilt last week. Should I clear the codes and see if they come back or would the failed transmission have nothing to do with the ABS? The ABS lights were on long before the transmission imploded.

I'm not quite sure if the transmission could affect the ABS system/module... I have a similar issue and am also leaning towards thinking it is the ABS module that's crapped out somehow. When I bought my '04 GTP I would get the Service Variable Effort Steering message in the DIC every time I'd start the engine; I eventually took it to a local dealer for a diagnostic and I was told ((I don't know WHAT he said about the EBCM and the rack because he spoke way too quickly)) I needed a new rack and pinion - which eventually I ordered one online (definitely not buying anything from the dealer) and had it replaced but to no avail. The mechanic actually did mention something about a code for the left rear wheel but I don't remember what it was. Actually just a week after going to the dealer, every single day after a while of driving (maybe 10 minutes or so) and several times a day, I will get two beeps and notification in the DIC that traction control and stability control have turned off, then followed by the warnings each time to service traction system, stability system, ABS system and brake system. And sometimes it forgets to mention the variable effort steering message but it will maybe 5 minutes later, lol. I really think (and hope) it is the EBCM that is in need of repair or replacement (I read somewhere someone will repair it for $99 if you ship it to them which is not terrible, unless you find a fully functioning one that matches your vehicle in a junkyard for less). I'm kind of pissed I replaced the rack for nothing (and I actually found out afterwards that the previous owners had already had it replaced a year before!)
Oh well, trial and error I guess, and believing idiots at dealers who want to rip you off. (they wanted to charge me $1,900 to replace the rack... )

Originally Posted by wickedfrisone

(they wanted to charge me $1,900 to replace the rack... )

Hence the nickname " Stealership "

Here's a little update for those following along. I found the RF wheel was afflicted with the infamous broken wire about 6 inches away from the plug. The LF was reading 5v and the hub was reading around 1100 ohms so I didn't go any further with that one. I spliced in new RF wire and the ABS/traction light went off. I drove it around a little last night and the ABS/traction light came back on. This morning when I started the car the lights were off and stayed off all the way to work. I hate intermittent electrical issues. I'll have to scan it again and see what, if any, codes are still there.

Well I hope that resolves the issue on yours- if so that'd be great as it doesn't involve repairing or replacing the ABS module. I have yet to get to check mine to see if they look good/are still working. Probably when I get to resurfacing the wheels.

Originally Posted by GYSOT1

Here's a little update for those following along. I found the RF wheel was afflicted with the infamous broken wire about 6 inches away from the plug.

6" which way ? Towards the hub, or towards the main wiring harness ? I ask because our Monte has chafed wires right at the hub. I figure it'll be to difficult to splice there ?? Leaning towards a new hub. Your thoughts ?

It was broken 6 inches from the hub plug. Not the wires from the hub to the plug. The hub wiring was ok. Fairly simple repair. Unplug from the hub, open the clips that hold it to the A-arm and then pull back the plastic wrap around the wires. I used a meter to probe the wires until I found where the break was. You can't see the break, it's broken inside the insulation.

Originally Posted by GYSOT1

It was broken 6 inches from the hub plug. Not the wires from the hub to the plug. The hub wiring was ok. Fairly simple repair. Unplug from the hub, open the clips that hold it to the A-arm and then pull back the plastic wrap around the wires. I used a meter to probe the wires until I found where the break was. You can't see the break, it's broken inside the insulation.

Thanks. Hub wiring seems dainty compared to the harness. I wonder if anyone has had any success trying to repair frayed hub wires. Mine must have been rubbing for a while, because the plastic clip was broken off, and it rubbed through the little white "jacket" around the hub leads. Seems like not enough room for an in place fix, and if it's gotta come out I might as well toss in a new hub. It's an OE hub with only 50K.

Ya, those short wires would be tough to splice.

The warning lights are still coming on periodically so I scanned it again last night. There are now 3 codes, one of them being new.

C0550 - ECU Malfuncion
C0036 - LF wheel speed circuit range performance
C0450 - steering assist control actuator

Based on those codes, the previous codes and the new C0550 I'm leaning towards a bad EBCM.

Found this article from a google search
I have a 2004 pontiac grand prix gtp with 78,000 miles on it and the tcs, abs, and the brake light is coming on. On the

Another update. I sent the EBCM out to cheap ABS to get repaired. Got it back and put it back in. That took care of all my issues except there is still a problem with the LF wheel sensor. It even fixed my C0450 steering assist control actuator error which I thought was the steering rack. Guess I'll have to bite it and replace the hub.

The new codes are
C0896 Device voltage range performance
C0035 LF wheel speed sensor circuit malfunction

Thank you to whoever recommended Cheap ABS. It was well worth the $100. A tip for anyone who will need to take the EBCM apart a trick I used to get those screws back into the holes was to put a dab of grease on the tip of the torx head. The screw won't fall off. I also trimmed a little bit of the mounting bracket to create more clearance.

Originally Posted by GYSOT1

Another update. I sent the EBCM out to cheap ABS to get repaired. Got it back and put it back in. That took care of all my issues except there is still a problem with the LF wheel sensor. It even fixed my C0450 steering assist control actuator error which I thought was the steering rack. Guess I'll have to bite it and replace the hub.

The new codes are
C0896 Device voltage range performance
C0035 LF wheel speed sensor circuit malfunction

Thank you to whoever recommended Cheap ABS. It was well worth the $100. A tip for anyone who will need to take the EBCM apart a trick I used to get those screws back into the holes was to put a dab of grease on the tip of the torx head. The screw won't fall off. I also trimmed a little bit of the mounting bracket to create more clearance.

Glad to hear that did *most* of the trick! I've been wondering if Cheap ABS was going to be worth it or not for my ABS issues. Also the EBCM does also utilize the wheel speed sensors' input to control the variable assist steering, so it's good to see it resolved that one too (that's the one I get every single time I turn the engine over, so I'm pretty eager to see that g bye-bye).
I guess now we know Cheap ABS is legit! Haha.

Another update. Finally got around to replacing the LF hub. Drove it around a little and no ABS light. Yay! Go to work today and as I'm pulling into the parking lot. Bam! ABS light. wth. Get home tonight to scan it and the C0035 code is back. LF wheel speed sensor circuit malfunction.

Pull the wheel off and check the plug and wire. I'm getting 4v at the plug. Thinking it may be a semi-broken wire I start wiggling it while monitoring the voltage. Nothing, voltage doesn't change. Now i'm thinking maybe its the plug? When I put it back together originally I used dielectric grease to make sure there was a good connection. What else could it be?

Cut the plug off the old hub, leave a few inches of wire, strip the ends, plug it into the car and then test your voltage.

Hopefully this is the last update. Ever since I unplugged the connection the ABS light has stayed off so it must be the plug itself. I'm calling it fixed. But in case it isn't I went to the junk yard and cut off some connectors I'll solder in if it happens again.