Intermittent ABS issue on C5
 

I have an intermittent failure of my ABS on my 2002 C5 Z06. I is only a track car/race in T1 racing trim. A friend of mine has a 2001 T1 Z06 and he has the same problem.

Some sessions I go out and ABS seems to work fine. Other sessions it fails right away and wheels start locking up. It seems to fail more quickly is I am driving hard and deep into the corners. If I drive just hard enough to get into ABS. but not in an agressive manner, it oftimes does not fail.

I get a persistent 1277 code, an occassional 1235 and if I recall a 1245. I just got back from the track last night. I will go out and verify that last code.

This problem has been going on intermittently most of this year. My two rear hubs were just replaced recently, twice in the last six weeks. The fronts six weeks ago. I have also had the ABS control box with the 12 solendoids rebuilt about four weeks ago and replaced the BCM.

Any ideas...?


Thanks

:bigears :bigears :bigears

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Wow...I had those problems as well off and on. Thought I could just "ease" on the brakes while I was getting the messages. Locked up the wheels and went into some pea gravel at Barber...:ack: Luckily mine went away replacing the rear hubs. Good luck to you...:cheers:

I looked up some info, I would say it might be a wiring issue somewhere. Especally with the code 1277, Maybe a bad connection on the PCM/Ebcm. 1235 could be from the hubs(But you already replaced these), but it might be bad pig tail or wiring also. My software wont let me post any info for you. sorry

John

Ollie, Here are some places to look
1277 is traction control its related to wheel sensor and may be a bad ground on the PCM
1235 is wheel sensor open or shorted to +12v
most likely a dirty or corroded plug connection at the sensor, were they cleaned with contact cleaner when changing out the hubs? it's agood spot to start looking.
the next possibilty is that the new hubs have bad sensors. however since it's intermittant most likely cleaning the connections and the PCM ground will fix it
1245 isn't listed so probably its a ghost (non issue)
:cheers:

In my experience most ABS problems are related wither to the wheel sensors or to the wiring. I would start by doing an exhaustive (and I mean exhaustive) check of all the wiring to the wheel sensors and the associated connectors.

Frank Gonzalez

And...there may be nothing wrong at all.

If I start lapping at 35psi and I grow to 42psi the ABS sensor goes wacky.

If I start at 32psi and never get past 41psi I'm good.

There is a threshold as far as wheel to wheel and front to back as far as revs per mile. If you grow the tires and already run an odd size you might be on the edge of that threshold. Say the C5's stock tire diameter is 26.5 inch. Running say 26.5 up front and a 26.75 in the rear already puts you out. Grow the rears some more and you might trigger the code.

Now this is on a weekender car with street tires I'm sure on a T1 car you don't want to drop the pressure a PSI or two just to fix the issue.

I'd check with a tuner and see if they can open up that threshold for you or better yet properly program the tire heights.

Oli -

Like frank said, check the grounds. I'd start looking at the one on top of the frame rail behind the left headlight. Then check the ones by the PCM. I don't have the doc handy, but there was one floating around that listed all the ground points in the car.

Unscrew the lug and rough it and the frame up with some sand paper. Also the C5 has that goofy black little box for distributing the grounds. Pull the wires out of that and check for corrosion.

Will the scca's inspector blow a gasket if you rebuild all of those wires with a proper lug? If not, you might want to look into that (seems like a stupid thing to bitch about - even dumber than carpet).

It's most certainly the wheel speed sensors, or possibly a bad ground somewhere on the chassis (if rust it an issue in your area).

I don't know who's hub's you are running, but if you are having issues with new GM hubs, then it may be something else, but everytime I've had it, I've replaced the questionable corner (either lost or excessive wheel speed from a particular corner) and it's gone away.

Maybe the new Van Steele hubs are worth a try for you, or just give up on ABS.

Thanks you guys. There is a lot of great stuff in this thread. I will run some of these down and let you know what I find.


Fastest regards,

Oli


:thumbs: :thumbs: :thumbs:

I had an intermittant ABS failures and right front hub codes all throughout 2007. I do LS autox, HS autox and a couple of HPDEs - Pocono and Summit point. Slid off on jefferson at the the top of the esses in Oct 2007 while locking up and corded a set of V710s. Code was 1226/indicated right front hubrotation disparrity(or some thing like that). Service ABS would come on on DIC.
This is what i did:
Replaced both front hubs, kurt at Phoenix/Palm replaced wiring harness to ABS unit, soldered in new connectors, I cleaned all grounds in engine compartment, took car to dealer and ran around w/OBD plugged in/got no bad signals. Sombody on this forum suggested that I check to see if I had copper washers on my SS brake lines. At the time I was using Russels and they had come with aluminum washers. What do i know? I installed the Russels w/their aluminum washers about 3 years ago.
In novemeber i put the OEM lines on with copperw ashers, in january goodridge SS w/copper went on....I HAVE NOT SEEN A SERVICE ABS LIGHT SINCE!!!!

oh yeah.. never even THOUGHT about that.. i knew it effected the AH, but is it sensitive enough to effect the ABS?


oli.. are the hub codes still coming after they replaced the rears?

i saw what sean did re the grounds.. looks like that is covered.

Had the problem with my 03 Z last year replaced all 4 hubs & now no issues

thought about it and it's not it.. Oli's 1277 is a hard code.. as soon as you reset it, it comes back.

less weight, go faster, I would rather bank on my skills (or lack of) than a system that may not work at the worst possible time, front straight at MMP is very long!

I pulled the entire factory wiring and all plumbing out, replacing it all new and better.

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Rick

I can't do that in my race class. GCR mandates a stock car for the most part....

Can you deliberately pull the ABS fuse(hell, put a dead fuse in)? At least then you wouldnt have surprises.

As long as the car does not show a Check Engine Light. That can be grounds for DQ.


Oli

I thought that was not an issue in comp mode but perhaps an issue in normal mode?

I run with all traction control turned-off.

Had a similar issue this past weekend except it was the battery sliding around and loosening up the connectors. A cheap fix.

Be careful with this one, having your ABS go at the exact wrong moment can replicate the feeling something breaking in your steering which could lead to an off track excursion. Also, if your running aggressive rear pads with no ABS than the rear tires will tend to lock up(or atleast upset the car) under certain weight transfer conditions. :eek: