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error codes io34, to72, traction disabled


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I posted this problem on another part of the forum but I think it was the wrong place. So, here we go. I have a 94 SLS and and when starting my DIC reads "--" after a few seconds. The traction is disabled, there are no mpg, coolant, tachometer readings. There is a very weak whine and I have noticed it since the traction control had been disabled. I have checked the grounds G102, G104, G100 and most of the easy ones. Still no change when starting the caddy. The car still rides smooth, has lots of power, gets good gas mileage. Anyone have the same problem. Wondering if there is a fix for this problem. I have Factory service manuals but there is so much to read, it will take me a long time before I could understand them completely.

Edited by wishfulmechanic
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I034 Loss of Powertrain Control Module Data

T072 Serial Data Link Fault

Both codes are data link codes, and your display goes blank. You have a problem with the car's network. This can be caused by any module that shorts out the data line. Someone with a 1994 FSM needs to step in here.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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I034 Loss of Powertrain Control Module Data

T072 Serial Data Link Fault

Both codes are data link codes, and your display goes blank. You have a problem with the car's network. This can be caused by any module that shorts out the data line. Someone with a 1994 FSM needs to step in here.

Thanks for the info but we need to go to the next step. How many modules will cause this problem and what are they? I would assume a MAP module would be one of the devices we could be interested in.

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I034 Loss of Powertrain Control Module Data

T072 Serial Data Link Fault

Both codes are data link codes, and your display goes blank. You have a problem with the car's network. This can be caused by any module that shorts out the data line. Someone with a 1994 FSM needs to step in here.

Just to add to the reply, I have a full 94 FSM set. The 2 manuals are 50lbs and have hundreds of pages. Where do I look for the fix?

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I would start with the section on dealing with the DTC T072 in your FSM. Since your dislplay is going blank, the network connection is the root problem. The I034 is also from a network problem, most likely. So, following the FSM instructions for fixing problems that throw the T072 DTC should clear the problems and the codes.

BTW, I got a copy of your original post as a comment on my profile today. I've been replying here as best I can, and here you get the benefit of many people who are much more familiar with your car and your problem than I am. I'll delete the comment on my profile.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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Well, I fix it...The IO34,TO72, traction disabled, PCM not working is all to do with the brakes. The traction control/ABS is well detected by sensors. If one of those sensors is given an out of range voltage, the error codes come up on the DIC. I have had these error codes a week. I replaced the brakes and rotors and the next morning the DIC was reading correctly again and everything returned to normal. So, there you are and to conclude IO34,TO72, traction disabled, PCM no data means your brakes needs maintenance. Thanks to all for their help.

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Thanks for getting back to us with final resolution. And, thanks for the nice summary of the symptoms, the codes, and the solution.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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I don't see the connection for brakes to affect serial data. you changed no sensors doing a brake job. what part did you change that you think fixed the problem? new pads/rotors has no effect on your loss of data. ABS data is determined by wheel speed which is hub bearing sensor. was your sensor harness loose?

Edited by joeb
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  • 4 weeks later...

I don't see the connection for brakes to affect serial data. you changed no sensors doing a brake job. what part did you change that you think fixed the problem? new pads/rotors has no effect on your loss of data. ABS data is determined by wheel speed which is hub bearing sensor. was your sensor harness loose?

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I don't see the connection for brakes to affect serial data. you changed no sensors doing a brake job. what part did you change that you think fixed the problem? new pads/rotors has no effect on your loss of data. ABS data is determined by wheel speed which is hub bearing sensor. was your sensor harness loose?

Yes, you are right in that the brake job did not fix the problem. I assumed it was fixed because the DTC display returned back to normal, but only for a day. When the car was lowered off the jack while doing the front brakes, I must have moved a sensor cable or something, don't know yet. The display has returned many times and indicates a intermittent. Will check the sensors on both wheels. I wonder how many there is that would cause this problem.

Edited by wishfulmechanic
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  • 3 weeks later...

I don't see the connection for brakes to affect serial data. you changed no sensors doing a brake job. what part did you change that you think fixed the problem? new pads/rotors has no effect on your loss of data. ABS data is determined by wheel speed which is hub bearing sensor. was your sensor harness loose?

Yes, you are right in that the brake job did not fix the problem. I assumed it was fixed because the DTC display returned back to normal, but only for a day. When the car was lowered off the jack while doing the front brakes, I must have moved a sensor cable or something, don't know yet. The display has returned many times and indicates a intermittent. Will check the sensors on both wheels. I wonder how many there is that would cause this problem.

I have been pondering over this problem. I left the car for a few days and when I start the car, the DIC returns to normal. The normal condition is only for a little while and the error codes return, IO34, TO72, etc. Also when I jack up the frontend to change the oil or do a brake job, the error code condition goes away for at least a few hours, then returns. The caddy still has the problem but we are still looking for the problem. Any diagnostic instructions will be appreciated.

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  • 9 months later...

well, here we are again,just about a year later. The problem still exists with the traction control being disengaged. TO72, IO34 and no PCM Data. It is not intermittent anymore. The DIC now has the fault being read steadily when I start the car. The error code readings I am getting are the same as my previous posts practically a year ago. I have been studying the FSM and have found so many sensors which could cause this problem that it is overwhelming. The car runs great, get good gas mileage and starts in seconds. I have used the caddies computer readout and still cannot read the PCM data. There is another socket I could use but I think it is for the ABS system. What kind of device would I need to read data from ABS system. Could the problem be with the ABS system all along.

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Both T072 and I034 relate to network data. T072 probably is thrown by a failure in the dedicated data line from the EBTCM to the PCM for commanded engine torque, part of the TCS logic. But the I034 means that the DIM (Dash Integration Module, the master computer for the car and the one that the OBD connector goes to) or IPM (the Instrument Panel Module) isn't seeing the PCM. The only thing in common with these codes is the connector to the PCM. Thus I would pull the PCM connector and clean it, and check for loose or pushed-back individual connections.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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