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View Full Version : 2001 Pontiac Grand Prix GTP ABS & TCS lights on UPDATED FIX



CJ_More
April 6th, 2010, 11:06 AM
I am stumped and I know there are some expereinced mechanics on here....:D

2001 Pontiac Grand Prix GTP ABS & TCS lights on constantly

ABS & TCS OFF lights came on, my power steering became stiffer and the car was harder to turn

DTC
C0450 - Steering Assist Control Actuator Circuit Malfunction
C0121 - valve Relay Circuit Malfunction
P0650 - Malfunction Indicator Lamp (MIL) Control Circuit

cheftyler
April 6th, 2010, 11:11 AM
Buddy of mine had a similar Grand Prix and had similar issues to yours and it turned out it was his speed/ABS sensors at the wheels.

MrMischief
April 6th, 2010, 11:14 AM
I've got the same problem on my 01 Grand Prix GT. According to the dealer it was a wheel speed sensor. Replaced it, same problem still exists.

cheftyler
April 6th, 2010, 11:24 AM
I've got the same problem on my 01 Grand Prix GT. According to the dealer it was a wheel speed sensor. Replaced it, same problem still exists.

My buddy had to replace all 4.

Jake_Blues
April 6th, 2010, 11:29 AM
I had a Grand Prix and the ABS/Traction Control lights came on, it was a failed wheel sensor (actually the wires to the sensor got ripped out by road debris), but I didn't have any of the steering issues you describe. I'd be looking more towards the sensors in the steering system myself.

-E

MrMischief
April 6th, 2010, 11:45 AM
Oops sorry I should say that the steering problem was solved by a replacement power steering pump. That one has lasted nearly 2 years, wife is saying it's bad again. Since it's spring now, it won't be driven very much so it's on the back burner

J Kimmel
April 6th, 2010, 07:22 PM
uuuhhhhhhh......

I think the problem is that its a Pontiac

theirishavenger
April 6th, 2010, 09:30 PM
I am stumped and I know there are some expereinced mechanics on here....:D

2001 Pontiac Grand Prix GTP ABS & TCS lights on constantly

ABS & TCS OFF lights came on, my power steering became stiffer and the car was harder to turn

DTC
C0450 - Steering Assist Control Actuator Circuit Malfunction
C0121 - valve Relay Circuit Malfunction
P0650 - Malfunction Indicator Lamp (MIL) Control Circuit


Does it have the electronic variable orifice steering (variable steering assist)?

We saw a lot of those that had the steering rate sensor go bad. Little sensor at the base of the steering column up under the dash.

edit: just read your description again. I'd bet good money that's what it is. I think if it fails the steering defaults to having less assist so you don't oversteer at highway speeds.

Chris

CJ_More
April 6th, 2010, 09:43 PM
Yes it does

Good info - I'll look that way Chris and let ya'll know!

CJ_More
April 7th, 2010, 10:15 PM
Gm Markley Motors Diagnostic

C0244- Ebmc not talking to each other
C0550- Internal EBMC fault
For C0244 Checked PCM connector for water inrustion
Looked OK
Noticed ECMB connector not seated properly.cc
pulled ecmb connector off and isp and ressembled connector
after isp. cleared codes and test drove abs and traction light came back now. Now there is EBCM and retest system for further ....
complete diagnosis only. customer declined repair

suggesting ECMB replacement $1500

further diagnosict required

CJ_More
April 7th, 2010, 10:17 PM
suggest $1500 ECMB replacement further testing

Should I be concerned/????

theirishavenger
April 8th, 2010, 09:38 AM
Only if you want your ABS and traction control to work. If you have an internal EBCM fault those systems will be disabled. Your service brakes, as a basic system, will still work, of course. Man, I used to hate giving my customers the estimate for those. Damned pricy.

edit: I don't have a schematic, but I wonder if you've had two failures: The EBCM and that steering yaw rate sensor. The sensor is a cheaper repair. Maybe do that first and at least that way you would restore normal steering operation.

CJ_More
April 8th, 2010, 07:21 PM
Hey Chris, seems you might have a GM in.

Can you confirm the part number for me?
EBMC for 2001 Pontiac Grand Prix GTP - 88894774

theirishavenger
April 8th, 2010, 09:27 PM
I can call the parts guys at the dealer I used to work at and confirm for ya 1st thing in the morning. That ok?
I was wondering to myself if that $1500 means the EBCM comes with the valve assembly all as one unit. If this is the case, and you are thinking of replacing it yourself, I think you need a scantool to complete the bleeding procedure on it. I'll ask in the morning when I call my guy.


Chris

theirishavenger
April 9th, 2010, 03:05 PM
Dude, sorry I'm so late. I did verify that part number. EBCM, and lists at $1138 or something like that. I assumed your $1500 or so was including the labor to replace. That was for the module asm only, and does not include the hydraulic valve assembly, so probably no bleeding. Sorry again about the tardiness.

CJ_More
April 9th, 2010, 06:49 PM
No worries Chris....thanks for the follow-up

I purchased the AC Delco part online
http://www.amazon.com/ACDelco-88894774-Control-Module-Kit/dp/B0010G2MHW

Yes Amazon sells the part - too cool

$605.00 shipped

I figure worst case, I'm back at the dealer to have them put it back on the tech 2 and I'm still ahead of the $1138.00 of the actual part price.

theirishavenger
April 9th, 2010, 08:57 PM
Nice! Good luck.

CJ_More
April 10th, 2010, 11:13 PM
I'll post up results

CJ_More
April 16th, 2010, 06:21 PM
**Update 4/16/10**

I received the ordered part from amazon 10:30am Tuesday 4/13 - Thanks Amazon prime over night shipping

I installed the new EBCM Wednesday evening after purchasing a longer shaft torx T20 - 6" shaft - insert joke here.

The install took roughly 1.5 hours and most of that was spent removing wiring harness, intake, cruise control module and carefully separating the associated plugs without breakage.

**Note EBMC install procedures**

Disconnect negative battery terminal

There are 2 nuts on either side of the ABS / TCS aluminum unit and pump – loosen nuts and remove 6 torx bolts of EBCM. Disconnect bottom plug and remove EBCM.

Make note of wave spring position for ABS and TCS on old EBCM. On the GTP there are no wave springs to reinstall.

Once old EBCM is removed pry the entire unit up another inch working either side right to left, carefully prying from bottom, moving the entire unit upwards. Clean mounting surface with clean rag and alcohol. There is a plug underneath that requires that extra inch of room to plug in and position new unit to mating surface.

Once mated reinstall 6 torx – top and middle 2x2 tightening in a star pattern to 26 lbs. Install 2 bottom torx and reconnect plugs. Connect negative battery terminal.

**

If I had to do it again I bet it could be done in under an hour…..

Both TCS and ABS light are NOT on and car functions properly. I have driven roughly 10 miles and the car has reached normal operating temperature. This weekend I will drive on the highway at speed, but I believe the issue has been resolved.

theirishavenger
April 16th, 2010, 06:35 PM
Back when I was a tech we used to insult each other with a popular phrase: "You couldn't fix a sandwich!" Then, when we actually did fix whatever it was, it was "I guess you CAN fix a sandwich!"

So, "I guess you CAN fix a sandwich!". :D

Glad to see it.:thumbsup:

Chris