: Aurora northstar based 4.0... computer issues... help!



IamMrHart
10-06-10, 11:59 PM
Hello all, I registered with a Cadillac forum... this one because it seems some people here are very knowledgeable with these cars... I am also registered with the Aurora forum as well, but no one can seem to help me out, I figure as far as I can tell the Oldsmobile Aurora is not very different from a Cadillac Deville. That's why I'm here
The problem I have seems complicated; I have a 95 Aurora that has issues, on the surface it seems like the transaxle is done for, but I'm not convinced. When driving at highway speeds, it refuses to shift into 4th gear, after about 2 attempts it defaults to the virtual 2nd gear or limp mode accompanied by the check engine light, (driving in 3rd gear is fine) until restarted, but the problem doesn't end there, the traction control and ABS light won't go off despite changing a wheel sensor hub. So I had a friend with a scan tool that could read the car scan it, and it turns out that I have multiple loss of communication codes all from the DERM, IPC, ABS/TCS, HVAC and the trans shift ratio A problem which I suspect is related to the communication errors... Can someone please point me in the right direction? It is extremely hard to find info on the Auroras and I have scoured the net looking

98eldo32v
10-07-10, 02:44 AM
What codes were/are displayed? You have to start there at least to try to get a grip on the problem. I don't know if the Aurora keeps codes in "history" like the Caddy's do.....

IamMrHart
10-07-10, 09:51 AM
What codes were/are displayed? You have to start there at least to try to get a grip on the problem. I don't know if the Aurora keeps codes in "history" like the Caddy's do.....

The codes I was able to retrieve from the Aurora were:
94 - Shift ratio A problem
133 - Loss of ABS/TC serial data
134 - Loss of IPC serial data
135 - Loss of HVAC serial data
136 - Loss of DERM serial data

From what I understand the car has a hybrid ODB 1(with the OBD 2 type port) computer system, so getting the codes out of this car is a challenge. I have a friend who has an old Snap-On scanner, and after pulling the battery terminal for a few mins, to clear the computer. I then with the scanner connected I went for the nearest highway, and as soon as the SES light came on I pulled over and reviewed the codes, which weren't there before. (listed above)
Sorry to bother you Caddy guys but the Aurora forum doesn't seem to be much help, and I figured since the cars are similar then maybe someone here has had this issue that might be able to point me in the right direction... I'm starting to suspect that one of those modules have failed, I have checked, and re-checked all fuses, and from what I can gather the only reliable way to truly diagnose this car correctly is to buy a tech1 or tech2, which are kind of out of my reach, and the factory service manual is not much help on this issue with out one

98eldo32v
10-07-10, 10:32 AM
When did the problems start occuring or did you buy this car with these known problems? Fuses may be ok, but I'd start checking ground wires, loose connections, anywhere the electrical system has to be grounded. You may have to acquire a factory service manula for deeper diagnosis.

98eldo32v
10-07-10, 10:33 AM
Was this car in an accident by any chance? Possibly you have wiring harness issue......

IamMrHart
10-07-10, 10:56 AM
Was this car in an accident by any chance? Possibly you have wiring harness issue......

To the best of my knowledge the car hasn't been in an accident. I only had the car 2 weeks when these issues begain. It ran great, then one day while passing another car it dropped into limp mode, and has done it ever since. The car sat for most of the summer since I have another vehicle, and was worried about doing damage to the trans, but I found out that if driven in 3rd gear instead of 4th it won't go into limp mode. The ABS/TC lights will still be on though, but once I shift into 4th... limp mode

97EldoCoupe
10-08-10, 10:16 AM
Sounds like an issue my friend is having with his Aurora. No power in 4th. I can't wait to get back there to help pinpoint the issue. Limp-mode is for loss of coolant/overheating issues -