madmatt9471

Bill,
I will be calling you this week. 1998 Corvette, EBTCM mounted in the rear (Early C5)

I am still getting NO COMM with my EBTCM, even though I had done a few thing in the sticky thread. Messing with the connections on the clip. I have done quite a bit of testing already so i will be able to answer some questions along the way without having to go to the Vette

It still happens, even when I pull the fuses(20AMP and 40AMP) the lights go off (ABS and Traction Control) and or if I unplug the ABS Harness it'll reset the lights and then I'll take it on the road or around the block and bamm it's back on again and "NO COMM"

The only code I am currently getting is a 1255 H in the TCS DIC, Arrrgh!

Last night I took the fuses out and let it sit all night, without them in.

5:50 AM saturday morning 8/8/2010: I just put them back in and went for a test drive, I hit the accelerator spun the back tires and Traction System Active message comes on, (Working good and no lights), I then did quite a few ABS checks (HARD braking) and it is working like a champ and the ABS System Active message comes on (No Lights on the dash) and everything seems to be working at this point.

Is it possible that once the unit heats up it is having this trouble? (thinking outloud)

Thanks for all and any help!

Thanks,Matt 661-406-7516

Bill Curlee

Matt

With that DTC Its best to remove the EBTCM board and inspect the internals. Also Disassemble the connector and look for bad wires/pins or corrosion. Thats NOT a good code to have. Hopefullt you will find something easy:

DTC C1255 EBTCM Internal Malfunction




Circuit Description
This DTC identifies a malfunction within the EBTCM.

Conditions for Setting the DTC
DTC C1255xx is set when an internal EBTCM malfunction exists.

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
When DTC C1255xx is displayed on the Scan Tool, it will be followed by two more numbers which should be noted along with any other DTCs that may be displayed. The additional two numbers displayed with DTC C1255xx are for aiding engineering to determine the cause of the internal malfunction.
Make sure the integrity of the connection between the EBTCM and the BPMV is secure, tight, and free from corrosion.
DTC C1255xx EBTCM Internal Malfunction (ABS/TCS Disabled) Step
Action
Value(s)
Yes
No

1
Was the Diagnostic System Check performed?
--
Go to Step 2
Go to Diagnostic System Check

2
Are any other DTC(s) present besides C1255xx?
--
Go to Applicable DTC Table. Refer to Diagnostic Trouble Code (DTC) List
Go to Step 3

3
Turn the ignition switch to the OFF position.
Disconnect the EBTCM.
Check for damaged, pushed out, or miswired terminals.
Was any damage found?
--
Go to Step 4
Go to Step 5

4
Repair as necessary.

Is the repair complete?
--
Go to Diagnostic System Check
--

5
Replace the EBTCM. Refer to Electronic Brake Control Module (EBCM) Replacement .

Is the replacement complete?
--
Go to Diagnostic System Check
--

madmatt9471

Thanks Bill.
I will get right on the "KISS OF DEATH" Code for my EBTCM

As always I appreciate the help - I might do some dissectiong and see if I can open this thing up, since the '98's are supposed to be unfixable - Hah! I'll fix it

I have the '98 Helms manual so if you have any additional pages you want me to examine or which one this one is on, let me know

Hey if you know anyone who might have one laying around (I know ) but it is worth the asking, I'll take it

I will also trace the harness wiring and see if there is anything wrong with it anywhere. Updates will come along the way

Remember: Any pages and numbers for my '98s HELMS manual you want and need me to look at, just shoot and I'll read it I am gonna find the pages that refer to it anywya, but if you have the ones I can go straight to then fire away!

Thanks,Matt 661-406-7516

madmatt9471

Okay Bill,
I now have the Module in hand and on the desk off the Vette!

What procedure can we go through to test some of the module's parts? (some of the diodes parts etc)

I see the Geletonous substance that it is sunk in, is there anyway we can remove the circuit board to test the other side's componants?

I can re-solder the joints on the circuit board facing me!

Any suggestions at this point would be cool - if you need pics of the module out and on the desk let me know and I'll get them onto Photobucket and on the forum.

Thanks,Matt

Bill Curlee

Matt

Almost anything in that silicone jelly is NON REPAIRABLE. The hard parts on the board and the connections to it and the solder joints are about all you can really inspect and repair. Examine ALL the solder joints with a magnifying glass and look for cold solder joints.

BC

madmatt9471

Ahhhhh Gooooop!

I shot some pics to post, I will check all the solder joints especially for those cold solder joints

Well onto the pics: I wish I knew how to check these little diodes and stuff. I am going to try to trace everything out someway.



































Bill or anyone that has some extra suggestions please let me know

Thanks,Matt

Bill Curlee

From the great pictures that you took,,, I really dont see anything that jumps out as bad. Disassemble the wiring harness connector back shell and check the wires, the pins, where the wires crimp into the pins etc......

BC

madmatt9471

Bill - Question: The "BIG" White wire on the circuit board to the right "Big White Dot" (these are on the flip side where the clip goes in and it has the Red=40 AMP, Red=20 AMP, Brown=12 V switched, Gray=CommI beleive?, White/Black=Grnd, Big White= not sure?)

Do you see which wire that is on your schematic - I think it is from the Magnasteer, am I right?
________________________________________ ____________________

I spoke with GM today and got all the INTERCHANGEABLE numbers for the ABS Module for the NON-ACTIVE HANDLING Corvettes (NON-JL4)

Here they are, these are all interchangeable and are succession numbers for our Nettes with NON-ACTIVE Handling (Non-JL4):Point to remember: All these are "OUT" of PRODUCTION and can't be bought new anymore

ABS-5/TCS/MSVA2 M (Non-JL4)

GM 16268689

GM 16257049

New GM # (Aparent replacement, but out of production )

GM 19244085

AC DELCO:

9367071

9350153

9353611

9356961

That's it and all these are "OUT" of production, "BUT" they are all interchangeable We can only find ones that are used and in good working condition.

I mapped out the back side of my ABS Module - it is a work in progress but all the colors that match are where they "CONTINUITY" tested out along a path.

The other side of our Modules are sunk in epoxy (I.E.- our Processor and the rest of the boards little electrical parts) on the '99's and up these little parts on the opposite side are accessable, due to not being sunk in epoxy like ours are

The Black/White DOTS that overlap are GROUND - I resoldered all the joints just to be sure there were no cracks in them and making full contact.

I re-did it all and then reinstalled it, took it for a 15 mile test drive and then BAMM it happened again, Lights came on TCS/ABS on the DIC and got the codes C1255 and C1256 "Internal Malfunction" which is the kiss of death for these. And then it came up in the diagnostic - TCS - NO COMM. bummer, I was really hoping this would work.

I believe it is the "Processor" (Big Square Shinny Thing) that is loosing communication, or lets say overheating/heating up and taking a dump! It reminds me of a PC that I had that did the same thing when it got hot, turn it off, let it cool down, turn back on warm up, work well for a while then the processor would take a dump computer act freaky.

Onto the pics: 1st one module unsoldered/stock:


2nd Pic Power, Comm, Ground, and a couple other goodies mapped out:


Remember: This is a work in progress, when I get it off again I will test more junk on it. I don't know what all the resistors are supposed to OHM out to or for etc. But this is a start

Thanks,Matt

madmatt9471

Add an extra "4" = 19244085

Thanks,Matt

TexasRedRaider

Looks like you have done a ton of research so could you tell me if the EBCM connectors are the same from 98-00? My 98 (front mounted) shorted and caught fire and I can only find a 99 and 00 harness. Also just to confirm what you said, active and non-native harnesses should be cross compatible rihgt?

Bill Curlee

Yes, all of those connectors should be the same. The more advanced EBTCMs may have more wires but the basic wires should be the same.

Why did it catch fire????????? Make sure that you don't have a shorted EBTCM.

BC

TexasRedRaider

Thanks so much for replying! I have no idea why it shorted. The car has been sitting about six months because I have been unable to solve my parasitic drain issue ( maybe it was this???). I took It out last weekend and it drove great, all temps and pressures where they should be. Then I got the ABS light on the dash and shortly after smelled wire smoke so I B-Lined it home, flipped the hood and saw that the AFT or rear most part of the plug was smoking and had actually caught fire. I yanked the ground off the battery and doused it with water. The fire ruined both connections. My radiator and hoses are new as are pretty much all components on the front of the engine so there was no fluid intrusion...and hasn't rained here in 4 months.

Worth noting I never had any issues with my EBCM/ABS before this, not even codes. I was able to get a reasonable ABS/EBCM module for $350 and I think Mark at vettenuts has a connector (he's looking).

Way before I parked it, I thought my drain was from the battery switch membrane thingy on the steering wheel which shorted open (the relay was hot too) swapped both but it still drained.

Bill Curlee

Save the old module... Remove the horn relay and see if the drain stops. Splice in the replacement connector and see where you are at.

Bill