Thread: 03 GTP ABS/TCS--NOT SO SIMPLE--Seeking advanced advise

Trying to be brief, and thorough, so to it. Bought-gambled on-03 gtp w/ 120k mi. in July. It's pretty clean in and out, obviously serviced recently, but still seemed neglected. Also, it had been lightly modded; lights, door locks, stereo, etc. Trying to get/be smart about it, working thru all normal stuff, fluids, plugs, brakes, etc. Most things worked, but ABS/TCS lights were on when I test drove it. I gambled it was 1 or more wheel brg hubs.

So, I paid $125 & had PCM reflashed to latest factory release at dealer. All's good. Service rep is real cool. Says tech felt play in fr rt hub & suggests I start there to get ABS/TCS working.

1) why would they lift it to flash PCM??

1st hub I put on I pulled out wires from back. DA--!!!! Waste of $-no, live & learn. Remove what I just broke & install other new hub. Test drive, still no abs/tcs. Proceed to replace rest of hubs. Both fr, & rr rt are zzp, rr lt is az. Still no ABS/TCS.

Back to dealer, $125 for diagnosis. Said 3 times, "4 new hubs, need to know exactly which parts are not working". They said, its the rt rr (zzp) HUB, it reads "0", parts + labor = $826, so I went to az, & put new hub matching good hub (rr lt).

Still doesn't work.

Dealer isn't really being responsive, no comment why. They won't even suggest 2 new hubs from different makes would be bad at same corner & everything else is good. Just stinky situation.

Additionally, I've checked all fuses, disconnected battey, clear codes w/ obdII (no codes to clear-but trying it all), voltmeter @ each harness @ hubs w/ ignition "on", all 4 get 4.70 - 4.71 v

2) Is 4.7 v what they should be?

Thought, maybe rr rt was cross wired somewhere, so -rewired pigtail(?), tested, still does not work. so i put it back.

Bought $200 scanner supposed to read gm abs, put I tested it in parking lot and it had no mention or acknowledgment of any ABS, said everything was good. Returned it. No luck renting one.

ANY HELP?
IS THERE A METHOD OF TESTING HUBS WHEN NOT INSTALLED?
CAN GM DEALER/TECH II ACTUALLY IDENTIFY A WIRING ISSUE?
Differnet yrs/models vary, ANY DETAILED WIRING DIAGRAMS FOR 03 GTP?

Sorry for length.
Thanks for any help!

Thanks tons guys. Esp. for link to have module rebuilt, seems like good deal--less than $200 at first look.

Dealer is going to look at it/scan it again next week, at no additional cost, which is cool--I like them again.

Still wish I could find detailed wiring diagram of 03 ABS/TCS like those posted in HOW TO section for ABD/ETS and would appreciate anyone that has it sharing and/or tips where I can find them.

Also would be awesome if I could find correct voltage requirement for hub speed sensor. It seems like a good sign that all 4 of mine are exactly same, but little odd to me that it is 4.7v....

I prefer to do the work myself--really, I simply don't trust anyone else messing with my project...

I'll update post when I learn something

Thanks--you're the man!
I"ll look into it thoroughly this weekend when not working against deadline w/ the man sweating me...
I wish I could trust dealer, if not them--who? But for now, they are will ing to talk to me and look at again, so I am cool w/ em

This is great.
Ok, this is what I KNOW:
ABS/TSC lights are on;
ABS/TCS does NOT work--lt fr tire is going bald fast & I replaced rr rotors & pads & put on 12" fr calipers, rotors, pads & have locked up brakes few times since;
dealer told me new zzp rt rr hub was bad, I asked, how do know, rep said, it "reads 0"--thats all the info I could get at the time--at the time I was assured everything else was good;
put new az hub on rt rr--and still no ABS/TCS, & lights are still on;
voltmeter test @ all hubs are the same, 4.70v-4.71v.

At this point, I'm not ruling anything out, esp. b/c of some of the wierd things, including elect., previous owner did. With that said, the ONLY other (besides ABS/TCS) electrical problem is display on the radio is out--All other lights/switches/gauges are now working.

It seems very unlikely to have 2 new bad hubs @ same corner.

IF I KNEW the hubs required 12v, I would start working on tracking the problem from there, but I dont KNOW proper voltage.

If I KNEW the problem was wire continuity b/t ebcm & RT RR hub, I would just re-wire that run.

but I dont KNOW....and dumping $ into it shotting in the dark is not an option for me.

Thanks for the dialogue. Its very helpful; to know TechII can't actually isolate wiring issues, and that it needs to be used as trouble shooting tool. Can't wait to talk to service tech next week.

OK, I can read/follow wiring diagrams, but dont really have good understanding of electricity, in general.

Dumb question, is testing "voltage" wrong approach, as apposed to "checking resistance" as suggested in replies?

had most of my weekend highjacked by fam. haven't made the progress I'd hoped, but getting there.

THANKS FOR LINK TO TOPBUZZ, exectly what I wanted, I think its an excellent, simple explanation of system and processes for trouble shooting.

THANKS FOR TEST METHODS OF HUB, makes perfect sense after reading topbuzz & gives another step.

zzp is zzperformance.com, fronts
az is autozone, I went w/ Duralast, rears.

Ya, I agree that the dealer diagnosis was pemature.

Using methods above, I've tested rears, including new one dealer said was bad so I replaced & so far, they ALL test good.

If I had this info I would have saved at least $300.

ABS shares fuse with AC CL, under hood, #28, 10a. Its good, ALL fuses are good. If fuse was out, then other systems, ie AC CL, would be out too. Just to be sure, I pulled it, started car, threw SES. Put it back, everything back too f'n "normal", ie SES off & ABS/TCS lights still f'n on.

I bought car from dealer, mystery mobile, no history/info. Had new; belts, hoses, tires,& much work obviously recently serviced (why/by who?) like; brake master cylinder, shift cable, AC system. But shamefully neglected brakes, shocks, fluids, orig plugs/wires, routine maintanence, etc. Additionally, it has modded; door locks, security, headlights, and add-on; narrow band a/f, b/v, & oil pressure gauges. So, on top of normal 9 yr old, 120k mi stuff, I'm worried previous owner tapped into most convenient hot wire he could find/other and created a low voltage condition somewhere, which (I think) can cause system malfunction without blowing fuse.

That's why I ask about proper voltage for specific yr/model?

From what I understand, system operates within both restistance and voltage specs. You gave me resistance, but voltage in a working system, is still a ? using pin connections from spare parts, I fashioned a simple flying lead for ABS connection, so I'm testing it with system connected.

To clarify above, all rear hubs test good. But when tested inline w/ system closed--hubs plugged in using flying leads--I dont get the voltage readings I expect, but without knowing proper spec, I'm guessing.

My guess at this point is, wiring short and/or bad EBCM. Anyway, w/ the help you've given me, Im working thru it. Keep you posted.

CODES

I'm at a loss. Too much conflicking info over ABS codes, and my experience doesn't match up...

Got a SES shortly after I got car. Found, fixed leak in vacuum line. Borrowed generic cheapy OBII scan tool from friend, cleared code, no problem.

Still was suspicious of previous owner, check body and PCM VIN, they match. Took it to dealer had PCM check & reflashed.

MY ABS/TCS lights were on, I didnt pay for that ABS diagnosis, only for PCM check and flash, but they said, they felt play in ft lt hub, and that it had NO codes. I checked again w/ OBII, which showed no codes. But ABS/TCS lights on entire time.

Cheapy does not read ABS, but wouldn't dealer's?

And, again, why would they check the wheels when I paid for PCM scan? And yet not tell me if a ABS code came up?

Is ABS code a MIL or SES code?

What about the TCS light on DIC? does that have a code?

I bought a ACTRON 9580, which advertises GM ABS codes. It connected properly and gave real time readings, but it gave me nothing for ABS, no aknowledgement of ABS system, good or bad.

Sale guy said he had same model and looked at it. He could not explain it. Said, it only shows ABS when it has a code. I said dealer says it has bad rr hub, and its not showing anything. He said, must be your computer. I said, dealer tested that ok, I paid for tool to get ABS info and you cant showw me ABS info, gotta get $ back.

I never left parking lot, so I did not do any software updates.... What ever hassle that means. Does anyone have this scanner, know how it works w/ these gpts?

I use plx kiwi (dont waste time trying cheapy blue toothe device) w/ android torque. I looked at features of scan gauages, shopped around. Have never used scan guage, so cant compare, but I love torque. But it does not read ABS.

I Dont understand why this is such a mystery.

I havent seen a ABS code with my own eyes. Dealer didnt say I had a ABS code, dealer said, rt rr hub reads 0, needs replacement.

Some clarification would be great?

And recommendation on scan tool that works w/ 03 GTP would be awesome.

Thanks

Originally Posted by SlowNA06

Uhh... false? Can I get a confirmation on this? Bill?


Only the major aftermarket resource for Grand Prixs. NBD.

The EBCM is supposed to disable the ABS for the duration of the ignition cycle once a code has been thrown but I have run into these many times where the ABS is still held hostage while while the ABS light is on and clearing it returns the system to normal (if there are no faults).

I've not gotten into "after market resources" for Grand Prixs, I'm a noob. Thanks for the info.

Originally Posted by Mr D

CODES

I'm at a loss. Too much conflicking info over ABS codes, and my experience doesn't match up...

Got a SES shortly after I got car. Found, fixed leak in vacuum line. Borrowed generic cheapy OBII scan tool from friend, cleared code, no problem.

Still was suspicious of previous owner, check body and PCM VIN, they match. Took it to dealer had PCM check & reflashed.

MY ABS/TCS lights were on, I didnt pay for that ABS diagnosis, only for PCM check and flash, but they said, they felt play in ft lt hub, and that it had NO codes. I checked again w/ OBII, which showed no codes. But ABS/TCS lights on entire time.

You can have play in the wheel bearing and not throw an ABS code. ABS codes aren't OBDII codes. If your ABS light is on then I would say that you have at least one ABS code.

Originally Posted by Mr D

Cheapy does not read ABS, but wouldn't dealer's?

I would hope so, but that doesn't mean that they actually looked to see if you had ABS codes.

Originally Posted by Mr D

And, again, why would they check the wheels when I paid for PCM scan? And yet not tell me if a ABS code came up?

I don't know why they would be checking your bearings cept maybe they were slow and looking for repairs to sell?

Originally Posted by Mr D

Is ABS code a MIL or SES code?

What about the TCS light on DIC? does that have a code?

ABS is not a MIL code. TCS light usually comes on with MIL light and goes off when MIL fault is fixed and then code(s) cleared. I do believe there are TCS codes, but I think they are in the ABS code set and I don't recall ever having to troubleshoot one. The TCS light just usualy comes on with the MIL because a current fault fits criteria for the PCM to disable the traction control.

Originally Posted by Mr D

I bought a ACTRON 9580, which advertises GM ABS codes. It connected properly and gave real time readings, but it gave me nothing for ABS, no aknowledgement of ABS system, good or bad.

Sale guy said he had same model and looked at it. He could not explain it. Said, it only shows ABS when it has a code. I said dealer says it has bad rr hub, and its not showing anything. He said, must be your computer. I said, dealer tested that ok, I paid for tool to get ABS info and you cant showw me ABS info, gotta get $ back.

I never left parking lot, so I did not do any software updates.... What ever hassle that means. Does anyone have this scanner, know how it works w/ these gpts?

I use plx kiwi (dont waste time trying cheapy blue toothe device) w/ android torque. I looked at features of scan gauages, shopped around. Have never used scan guage, so cant compare, but I love torque. But it does not read ABS.

You scan your PCM with your phone?

Originally Posted by Mr D

I Dont understand why this is such a mystery.

I havent seen a ABS code with my own eyes. Dealer didnt say I had a ABS code, dealer said, rt rr hub reads 0, needs replacement.

Some clarification would be great?

If your right rear speed sensor reads zero, I expect you have an ABS code. If your TCS light is on, I would expect you also HAVE an MIL light on too and the TCS will go off with the MIL fix. If the MIL is off, then you may have a TCS code, but you need to scan ABS (EBCM) to see the code.

You need your PCM and EBCM scanned and all codes documented. If the scanner will let you read data, you need to drive the car and watch the speed sensors to see if you do have a speed sensor reading zero.

Originally Posted by Mr D

And recommendation on scan tool that works w/ 03 GTP would be awesome.

Thanks

Scan tools cost a lot, I wouldn't know which to suggest. I would suggest having a mechanic that already owns one scan it for you.

I did some looking today and this is what I got. This is courtesy of general motors, for an 03 GTP, for an ABS light that is always on with no ABS codes present. To do their tests, you need a universal pinout box (J 39700) w/ cable adapter (J 39700-530) and the testing ends in one of these three places. I can get you the actual test steps if you need them.

1. Replace EBCM
2. Repair the ABS indicator control circuit (there's an open or very high resistance).
3. Replace instrument panel cluster.

I would have an ABS scan done with a quality scanner so you're sure if you have codes or not. If there's no codes, I'd lean into it being the EBCM as well.