1995 Deville has Traction Disabled and multiple codes

[oregonk5]

1995 Cadillac Deville base model 4.9L, 135k

Recently the car has had the TRACTION DISABLED light popping up more and more frequently. At first it would come on then stay off for most of the drive. Now it comes on repeatedly while driving.

First codes I pulled from the CCC was IO32, which actually has been in the history since I've had the car last few years. There is also a T072 and T077.

I removed the harness plug from the ABS module and cleaned and inspected. First drive out the light stayed off so I thought I had it licked. Next drive it came on with a vengeance.

Today I hauled scan tool and pulled these codes from history:
B1022 IPC Dimming Port
B1033 Loss of SIR serial data

And these current codes from ABS system:
C0072 IPC Serial Data Line Malfunction
C0077 PCM Serial data malfunction.

There are a couple other quirks which may/may not be related. Sometimes during the same the dash HVAC would stop blowing. Literally the fan would just stop...then it would just as mysteriously restart! Checked the blower connection and it was clean and unmelted. It hasn't done it since the weather turned cool and I'm not using AC consistently. The other weird thing: This car used to average 22mpg on the highway. The distributor wiring rotted out and I had to put a new distributor in it. Timed to factory specs (in fact, I've double checked it twice). Since putting the dist in, I can never get over 18.1mpg. Maybe coincidence? I've always used premium.

Anyway, sure could use some input on where to go with this one. Sounds like IPC or connector failures may be common on these?

[oregonk5]

So this morning, I removed all the PCM, ABS and various fuses from front and rear fuse box (one at a time) and cleaned all the connections. (I had read on another post how a loose ABS fuse contact had caused similar codes).

I then went in and cleared all the codes. Fired the car up and it went through it's re-learning curve. After it had warmed up I took off down the road. Dash HVAC wouldn't blow. No error codes -- on the display, simply wouldn't blow. It was about 40 degrees F outside and I had temp on 80. Banged on the dash a few times, still nothing.

Finally about 5 miles down the road the blower fan came on and it performed flawlessly on the way to town. No Traction Disable message either.

I know this doesn't really tell me anything but it's an interesting story!

Any input, gang?

[Cadillac Jim]

The heat won't com on until the ECT says that the coolant temperature is high enough for the HVAC to blow warm air, so the delay could have been normal.

You *may* have fixed the electrical gremlins when you cleaned up the fuses.

Drive it for a few days, check the codes again, and see what happens.

[oregonk5]

The heat won't com on until the ECT says that the coolant temperature is high enough for the HVAC to blow warm air, so the delay could have been normal.

You *may* have fixed the electrical gremlins when you cleaned up the fuses.

Drive it for a few days, check the codes again, and see what happens.

Hmmm, the defrost has always blown as soon as the car was started before. Besides, it was well warmed up before I took off today. Made the whole 25 mile trip in with no lights on. On the way home, Traction Disabled is back on repeatedly! Pulling codes tomorrow.

[oregonk5]

Took the ETCBM connector off again today and made sure the ground bar wasn't shorting. Also took off the dash pad and checked the IPC connections. Cleared all codes and drove. Again, it took about 15-20 miles and it came back on. When I stopped, pulled the codes and had:

T072 and T077 as current codes and P052 and I032 in history.

[oregonk5]

Removed the PCM connections today, even reseated the PROM. Had the same result, drove about 20 miles with no light on, turned off the car, it sat for an hour or so then after driving again light comes on.

I think I'm seeing a curious pattern emerging: It seems like the lights never come on at initial start up and drive. Only after the car has been restarted later in the day, then the warning light comes on repeatedly. Don't have any idea how this would factor into anything but it sure seems like the pattern. This strike a bell with anyone?

[Cadillac Jim]

It sounds like an intermittent problem in the EBTCM. An example is a bad connection inside the connector for the EBTCM. Another cause can be the relay inside the EBTCM going bad. The car's modules store data on many things right when some codes are thrown. A dealer can read that with a Tech II and tell exactly why the code was thrown.

[oregonk5]

Thanks for the input, CJ. I have a Tech II, that's how I'm pulling the codes. Nothing seems to be telling me why the codes are being thrown....I may try finding an EBTCM at a junkyard and see if that fixes it. I really don't want to take it to a shop because I don't know of any personally that wouldn't just throw parts at it, too. If there really is an open in a circuit, they would probably have to charge more than the whole car cost me to fix it!

[Cadillac Jim]

I wouldn't change the EBTCM until I had a diagnosis. It's a big job, the right EBTCM depends on the options on your car (RSS, ESC, etc.), and the EBTCM needs to be programmed for your car using a Tech II once installed.

Check the freeze frame data and see what is happening when the code is thrown.

If nothing tells you anything, get an Ohmmeter and check the resistance to ground from the black wires in the connector, then try to pull each of the wires out of the connector and see if any of them pull out. This is in the FSM and Goodwrench training, and finds a lot of very elusive intermittent problems, but practically nobody does it except do-it-by-the-book techs.

I had grief for a year with my car until a Goodwrench tech did that; he found two poor grounds and the big pink wire pulled right out. Fixed that, bingo, all the problems went away, fixed while I read a magazine, drank free coffee, and ate junk food. Another dealer was trying to get me to buy a $2,000 discontinued wiring harness and put it in (another $1K to $2K), and the dealer tech and a mechanic were trying to get me to "drive with the lights on" or scrap the car. Prior to that I had bought a new EBTCM, found and fixed EBTCM missing connector pieces, etc. to no effect other than some change in the symptoms whenever anyone messed with the EBTCM connector.