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Discussion Starter · #1 · (Edited)
I have a 2007 Saab 9.3 Aero 2.8T 6 speed automatic 83k miles. The car had an incident that pushed the driver’s headlight back into two large connectors and a few smaller ones, crushing them. These connectors were badly damaged and cracked with several broken wires including broken plastic. I tried to splice the damaged wires using short wires and cramped connectors.

I am assuming that powertrain bus info goes through these wires and connectors; including the twisted pair CAN bus wires, because I have DTC’s indicating a high speed bus failure with the ECM, TCM and SLM - U2105, U2106, U2146 in Limp home mode. Should I replace the drivetrain wiring harness or just rebuild the broken connectors? Does anyone know how the engine bay wiring harness is segmented and which harness I would need to make the repair? Also does anyone know if a 2008 Saab 9.3 Aero 2.8T 6 speed automatic wiring harness would work in my 2007?


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From e-mail conversation in case it helps anyone later:

Brad also told me that the large fuse & relay panel on the driver's inner fender was damaged, that was an important thing to include:

There's nothing wrong with just repairing the wiring, but the CAN leads are extremely voltage sensitive. You need to use quality crimp splices that have adhesive heatshrink over the joint so moisture can't enter.

The fuse box being damaged is an important point I saw you left out of your post of the forum. That fuse & relay panel has a computer module inside. You will have to replace that and repair any damaged wiring, then the new panel has to be programmed to the specs for your car by a SAAB tech or dealer.


Hello Drew,
Thank you for responding. Please call me any time, I am kind of lost here. There may be 1 or more malfunction computer beyond the wiring problems. I really need help diagnosing the ECM, SLM to TCM failure. The car had a bad incident with a culvert. It broke the drivers head light and bumper cover, cracked the rim and broke the CV joint, tweaked the shock tower bent the cradle. It was put back together with new and used stuff. The engine seems to run fine, but I am having issues with the transmission shifter logic after the ignition is turned on. The system is always in limp home mode and gets stuck in ether 6th , 5th or 2nd after reset with a OPCOM scanner and then when the key is recycled it goes into 5th or 6th gear. The car had the Xeon lights and they were removed and cheaper HT7 head lights were use, but the lighting system seems fine. The airbags did not deploy, but lot of codes. I noticed under load the negative side of the battery cable gets warm to hot. Here is a full list of codes I am getting with my OPCOM computer based scanner.





Battery cable getting hot is not good, and may be the cause of so many faults being set.

A lot of times if there are physical wiring problems or damage to modules, then other modules will erroneously throw faults due to low or out-of-range voltage signals, or loss of communication with other modules. Get as much of the physical wiring damage fixed as possible.

Once the physical damage is repaired, clear all the faults in all modules, then cycle the key and drive the car a short distance, power it off, then re-scan and see what faults returned. Then start addressing those.

Check what the voltage drop from the alternator to the starter to the battery is. There shouldn't be more than 0.250 VDC or so difference across the cables (If you read 13.5V at the alternator, you should see at least 13.25V at the battery posts - any more of a drop in the cable will also throw faults).

The underhood fuse/relay panel is called the Underhood Electrical Center (UEC), unscrew the 3 large male Torx bolts and the top of the panel lifts out, and there are 3 large connectors underneath. Check for damage, and check the harness for those 3 connectors for damage.

The TCM (Transmission Control Module) is the small computer mounted to the side of the battery basket, it has two large multi-pin connectors coming out both sides with lots of small wires, check all of them for damage, that might be where the TCM faults are coming from.

The SLM (Shift Lever Module) is the actual shifter in the center console. In addition to the cable that shifts the transmission there are some sensors and another control module in the lever. The fault will be in the communication between TCM-SLM, or TCM-UEC, or UEC-SLM. Again, probably damaged wiring.

Good luck, there is no silver bullet for crash damaged wiring like this, you just have to find all the damage.

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Hell0, I have a problem. I have Saab model 93 1.9tdi from 2007. and ther is a problem with traction control on tashboard. it cuts off a diesel and drives very slow. After conected to the computer it says error U2105 - Can-Bus No Communication with Engine control Module. Can enyone tell me anythink about it. Anyone had problems like this before and how to resolve it??thanks
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