GTB/ZR-1

***I already did a search on this issue***

I was trying to adjust rear ride-height & was moving the car back & forth in the driveway trying to get the rear to settle for measuring when this came up on the DIC.

I tried clearing the codes, unhooking the battery etc. It comes on after I start the car when I put it in gear & engage clutch.

Question is: I have some important events coming up & want to know if the car is competition-worthy? I turn everything off when I race, so I don't care if the active handling/TC work.

Also, I'm going to the Z06 fest in BG and I'm thinking of driving the car up, rather than trailer it--will it be OK on the trip?

I've had a C5 in one form or another since '98 & this is the 1st time I've had to deal w/ this.

TIA people

AU N EGL

Check to make sure your conections are secure.

wtknght1

Normally the ABS goes out too...which can suck! I turn everything off as well, but the ABS is still active. You might want to check that before you go out on track and start pounding on it. A flat spotted tire and the possible associated spin could be painful.

freefall

What codes do you see?

When I've seen that message, the "Reduced power mode" wasn't too far behind, and I'd guess its effects on your time would be unpleasant.

GTB/ZR-1

Yeah, that's what I'm afraid of...

I just c'ked the code--you ready for this?

C1295 Brake Lamp Switch Circuit Open

I did a few diagnostic run throughs on the DIC & that's all that comes up.

I reset the 1 code over & over--it still comes up serv ah/tc. I even did it while the car was running & heard the little servo motor buzz & the code came back up.

I noticed something interesting. I reset it, then I started the car, turned off AH/TC & drove the car forward only around the block--no problem. I pulled it in the garage & went into reverse--there it goes again! Seems like it only happens when engaging reverse.

Man, I'm confused here

wtknght1

I seriously doubt that having a reverse light burned out could cause that code, but looking at what you put (code explanation), it's worth a shot I guess. Check your reverse lights.

Did your ABS still work???? That's the real issue in my mind.

tigerdrvr

I hate to say it, but those sound like the symptoms I experienced when my EBCM (electronic brake control module) went south...

John Shiels

check the connections at the wheel sensor they may be loose where it plugs into the hub.

GTB/ZR-1

Well AU & John, since I was adjusting rear ride-height & prodding around back there--it's worth a shot.

Chris, I didn't stomp the brakes while going around the block--I'll try it (hope the homeowners assoc doesn't send me a letter )

tiger--I sure hope that's not the case...

GTB/ZR-1

Update...

I took all the wheels off & c'ked all the connections--all attatched.
I took it around the block & got on the brakes pretty hard--it's hard to tell w/ the 710s on the car, but there was some lockup.
It accelerated OK w/ the TC light on--didn't seem to balk.

When I reset the code (c1295) w/the car running, what sounds like a servo cycle off--then cycles immediately back on along w/ the service AH/TC on the DIC.

I spoke to RAFT today & he looked it up. Unfortunately tigerdrvr may be right--ECBM...
I called the local dealer & it's abt $1100 to repair. I wonder if I could install it myself--anyone know where is it's located?

Thx people...

tigerdrvr

I hope I end up being wrong, but, if I'm not I did do some research before I replaced the EBCM which might be helpful.
What I came up with was two options: either buy the part from someone like gmpartsdirect for about $600 or go ask for a deal from my local dealer. I figured that as the car had only come off warranty six months prior and the EBCM was a safety related part, that they should be able to do the replacement with some kind of warranty type provision or accomodation, which they did, meeting me halfway on the job and charging me right at $600. This saved me the hassle of changing out the part myself (which doesn't look like too big of a job, just a bunch of brake lines and stuff, plus the need to bleed the system when done. It's up front, driver's side, just behind the radiator...kind of) at the same cost as the part would have been.

NV MY C5

See if Gene has one. It is located on the drivers side in front of the engine. It is easy to change. Brakes need to be blead after changing. I think it took me an hour and a half last time I did it.

Lancer033

if it is the EBCM it's easy to change out yourself
http://www.klh-racing.com/AH_TC_ABS_Info.htm

GTB/ZR-1

Thanks guys, I ordered one from Gene @ Fred Beans today for $680 or so--it listed for $1049 (!)

It should be here on Fri...

I'll keep this thread posted

GTB/ZR-1

Bad news...

I manned up & went in and installed it myself (I'm by no means a master mechanic).

I'm still getting the service AH/TC. I reset it a few times & unhooked the batt for a while to be sure--no luck.

Great, I'm out $700 unneccesarily & back to square 1. Any other ideas? I did a search on both forums & c1295 has not seemed to be an issue before--I guess I'll be the pioneer on this one...

Bill Dearborn

The code is found under ABS in the Service Manual. Here is what the Service Manual has to say about the code:
DTC C1295
Circuit Description
The electronic brake control module (EBCM) sources 5 volts on the stop lamp switch signal circuit when the stop lamp switch is inactive. The voltage is supplied a ground path through the stop lamp bulbs.

Conditions for Running the DTC
The ignition is ON.

Conditions for Setting the DTC
The stop lamp switch input voltage is between 1.87 volts and 5.03 volts for 2 seconds.

Action Taken When the DTC Sets
If equipped, the following actions occur:

The EBCM disables the TCS/VSES for the duration of the ignition cycle.
The Traction Control and Active Handling indicator turns ON.
The DIC displays the following messages:
Service Traction System
Service Active Handling
The ABS remains functional.
Conditions for Clearing the DTC
The condition for the DTC is no longer present and the DTC is cleared with a scan tool.
The EBCM automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.
Diagnostic Aids
Possible causes of this DTC are the following conditions:

A signal circuit of the stop lamp switch is open.
The stop lamp switch is misadjusted.
Verify proper stop lamp switch operation using the data list of the scan tool. As the brake is applied, the data list displays the stop lamp switch ON within 2.54 cm (1 in) of travel.
All brake lamps are open.
All brake lamp grounds are open.
Circuit has a wiring problem, terminal corrosion, or poor connections.
Loose or corroded EBCM ground or ECM ground.
An internal EBCM problem.
Test Description
The numbers below refer to the step numbers on the diagnostic table.

This DTC detects an open stop lamp switch signal circuit from the stoplamp side of the splice pack to the EBCM.

The EBCM sources 5 volts on the stop lamp switch signal circuit. This small voltage has a ground path through the stop lamp bulbs. This DTC sets if the path to ground is open.

Since you changed the EBCM it seems more likely you have a wiring problem. I did not copy the diagnostic chart since you need a scan tool to use some parts of the chart. However, you should be able to come up with a modified diagnostic from the description above that will let you find the problem.

Bill

GTB/ZR-1

Thanks for the rundown of the code; Although, I'm tapping out @ this point & bringing it to a dealer & putting a Tech 2 on it.

The car has been stone-reliable for the 3 1/2 yrs I've had it--I hope it doesn't start acting up on me now.

BTW, the AH/TC will not come on now after I re-start the car and do NOT put it in reverse. I turned the TC off & got on the car--all seemed normal.
I pull it in the garage & put it in reverse, and the AH/TC immediately come on--strange...

GTB/ZR-1

Okay, good news...

I took it to the dealer & luckily the tech was great--a C5Z owner & he had a real hotrod F-body he had on his lift that a 408 will be going in--real car guy

He listened carefully to the symptoms & hooked the tech 2 up--C1295.
He c'ked the fuses & connections for corrosion which I did as well to be sure. He c'ked under the dash to be sure the proper voltage was there.
We noticed the brake lamps weren't working, only the amber part of the amber euro lamps.
I asked him if the harness for the euro lamps could be the culprit--he asked "what harness"?????? BINGO!

The harness contains a diode that went bad, which in turn caused the C1295 problem, as the circuit was open (just like the code suggested!).

Okay, now does someone need a perfectly-good-working EBCM I have an extra of now?

2000BSME

sorry,

I've got almost the same problem, but different code (1226), and a new wheel sensor didn't solve it either. I went to my event this weekend and was unaffected, but I paid good attention to make sure that I never got into a brake lock up scenario.

Bill Dearborn

How often does it happen? Here are the conditions for setting that code:
DTC C1226 RF Excessive Wheel Speed Variation
Circuit Description
The speed sensor used on this vehicle is a single point magnetic pickup. This sensor produces an AC signal that the EBCM uses the frequency from to calculate the wheel speed.

Conditions for Setting the DTC
The DTC can be set anytime the brake is not depressed and no wheel speed sensor hardware DTCs are present, and the EBCM sees a wheel speed variation of more than 14 km/h (9 mph) for 2.5 seconds.

Action Taken When the DTC Sets
ABS/TCS/Active Handling (if equipped with RPO JL4) are disabled.

Indicators that turn on:
ABS indicator
Car Icon (TCS indicator)
Messages displayed on the DIC:
Service ABS
Service Traction System
Service Active HNDLG (if equipped with Active Handling RPO JL4)
Conditions for Clearing the DTC
Condition for DTC is no longer present and scan tool clear DTC function is used.
Fifty ignition cycles have passed with no DTCs detected.
Diagnostic Aids
It is very important that a thorough inspection of the wiring and connectors be performed. Failure to carefully and fully inspect wiring and connectors may result in misdiagnosis, causing part replacement with reappearance of the malfunction.
An intermittent malfunction can be caused by poor connections, broken insulation, or a wire that is broken inside the insulation.
If an intermittent malfunction exists refer to Intermittents and Poor Connections in Wiring Systems.

Bill