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Discussion Starter #1
Vehicle: 2006 Saab 9-3 SportCombi Aero
Issue: Vehicle will engage systems when the key is inserted and turned, though if the issue is present; the gas gauge "bumps" but will not display the actual amount of gas in the vehicle, the SID will indicate a Traction Control Failure & Stability Control Failure (I feel it should be noted that no ABS light is indicated in this) and the vehicle will not turn-over, let alone start, it is also noted that the fuel pump does not seem to engage. We have bypassed the relay in the UEC with a positive result for cranking, though the vehicle still will not start.
Background: The current issue kind of cropped up while we were troubleshooting headlamp failure. Both headlamps failed at the same time, one of the ballasts had been replaced, so after verifying both the bulbs and ignitors on my xenon headlights were working, we moved on to swapped the UEC, the ABS control unit, and running a Tech-II with Saab Software - turned out the ballasts both went out and once replaced, the headlamp failure was resolved. Though we are left with the crippling Traction/Stability Control Failure. The tie-rods were replaced, though no issue occurred until sometime after. Communication with the ECU seems to be clean, so we are pretty confident the computer is talking to everything as needed. Faults u2105 and u2106 came back on the Tech-II, being missing TCM and ECM on BUS.
Suggested Resolves: Find the wire that is the culprit and fix it.

Continuing my search for specific information will be happening, so I will keep adding as I find steps I am taking to resolve this issue. What I am hoping for is some guidance on which specific wiring harnesses I am looking to test, and how. Taking a quick look at the various harnesses in that driver-side area of the engine-bay has not yielded results, and all tested grounds appeared to be as they needed to be. I am pretty confident it is a wire, just which one where?
 

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Discussion Starter #2
Hey all - I wanted to help anyone verify that they have seen me asking for help in other areas:
No worries, not asking anyone to go to them if they do not want - just sharing that I have posted in both of those seeking assistance with my 2006 9-3 SportCombi Aero
Also, I have seen plenty of other posts with similar issues and attempts to troubleshoot, so feel free to point me to already completed threads - I am putting this together to have a single thread of what all has happened, and maybe help others get to a resolution themselves.
 

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I would look at the ABS module.
 

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Discussion Starter #6
U2105 00 by itself is EHPS
U2105+U2106 00/72/7F is TCS/ESP (ABS)

Communication, P-bus, Motronic E9
P-bus wiring diagram, ME9

Wiring diagram will help isolate disappearing control modules. If harness broken, the break is past the last module that can be contacted.
Not sure if these read-outs help refine or verify your suggestion. My process for tomorrow will be following any wiring diagrams I can track down tonight. I'm focused on following the communications from the BUS to the TCM and ECM, then ultimately the ABS (?) or vice-versa...

I still feel a little blind.
 

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Yes, check the wiring diagram. P-bus passes through the TCM/ESP and UEC on the way to TCM and ECM, which are at the end of the P-bus. AHL is also past the TCM/ESP on the bus, tapped off the UEC.

EDIT: FWIW, ECM and ECU are often used interchangeably. Confusing.
ECM also means generic Electronic Control Module.
 

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WIth the Tech2 displays you show, I would start at the UEC (since you can talk to it). Both the AHL and TCM P-bus connections come from it. Don't forget to check for AHL/TCM power supply, too.
 

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Rereading your original post, the P-bus to the ECU passes through the TCM in your car since it's AT. Since you say you can talk to the ECU, that means the P-bus wiring connecting to the TCM is OK. So there's some other issue there...power, TCM itself, etc. Same with the AHL, I think. You may have two issues whose only plausible link is that both missing modules connect to the replaced UEC for data and power.

AHL component list
AHL wiring
TCM component list
TCM wiring

There's also a complete UEC pinout available as a link from either component list, so you can check for TCM power (multiple connections), TCM starting control, and +15 to AHL, for example.
 

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Discussion Starter #10
  • I tested the connections and was able to confirm power to the TCM from the UEC using this diagram
  • Power is able to get to the TCM, though a possible non-point I noticed; my wires are switched, top and bottom, based on this diagram
  • We are moving beyond the AHL as it was disconnected by a buddy that has been helping me. He is the owner of the Tech2.
  • Focusing on the issue of non-start, I am testing an energized system to identify power flow to the TCM
  • Using the WIS as an downloaded program, I have been following it's on-board troubleshooting, results to come
  • I am concerned the TCM is failing, internally. Is that possible? The module work without issue and then just kill? I am unsure if it is wise to go by anrule of thumb that a module is either bad or good.
Thank you for the help so far - looking forward to any further insight
 

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Discussion Starter #11
Ok, so.. I turned the car off. Left the ignition on. The headlamp leveling stuff went nuts making noise. I went back to the car to see what changed and the gas gauge was reading how much fuel I actually have, not hanging up below E. TCS/ESP failure still present, but the car starts...

AHL/HLL module was disconnected before, reconnected now for the energized testing. Talked to a few others and I'm being pointed to a potential faulted wire, again. Seems I should just go ahead and replace the section of harness that routes the TCM and HAL out of the UEC?
 

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Given that you replaced the UEC, the odds are halfway decent that an intermittent in the harness is somewhere near that, since that end has probably been flexed the most. Wiggling the harness should let you know if you need to change it out or splice around something. Make sure all the connector pins on both ends (TCM & UEC) are up to snuff, too.

OTOH, if the car is now starting/running reliably, you may just have had to reseat all the connections.
 

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The pins that I can see look fine in the photos above. I haven't been able to load the video, but Google and I haven't gotten along since they started, when I noticed their cookies had expiration dates 99 years in the future.

Here's where I think you are currently. Feel free to correct any assumptions which are wrong.

1) You can talk to ECU
2) You cannot talk to TCM
3) AHL is removed
4) 1) and 2) are still happening at the same time
5) You replaced UEC and ESP
6) All P-bus modules have power and data (verified via voltage or resistance measurements)
7) Grounds have been checked

If the above is true and a complete summary, I have the following questions:

1) Are the replacement UEC and ESP new or used?
2) Are all UEC fuses and relays from the new UEC or the old one?
3) did you remove the old and add the new ESP and UEC using Tech2, or did you just swap in new ones?
4) Can you still talk to ECU? <--- sounds redundant, but humor me here
5) Have you reset the ECU with Tech2? By pulling fuse 2 in the UEC? By disconnecting battery?
6) Is the car currently starting or cranking without bypassing main relay?
7) Have you looked for any other connectors which may have come off during all this work?

What I have to do in situations like this, so I don't get too confused, is ask myself these questions:
What was the last thing I changed or modified?
Have I changed only one thing at a time before making measurements or observations?
Do I have a single failure or multiple failures, perhaps acting in concert so they look like something else?
What is it that I am actually seeing from my instrumentation?

Sorry about the long reply, but in an extended ordeal (for you) like this, it's a good thing to periodically pause, summarize everything, and rethink the issues.
 

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You also can't neglect the possibility that TCM has chosen this moment to go to the heavens. Murphy's law, and all.
 

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For stability control thing, check your rear brake calipers, stuck calipers can cause stability control light on SID, at least it is in my case, I have this warning message came up intermittently when brakes a lot driving on local/city roads, it turned out my passenger rear brake caliper seized up, replace the caliper, everything is fine now.
 

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I can fill some of this out as i have been sort of helping KuztomSaab

If the above is true and a complete summary, I have the following questions:

1) Are the replacement UEC and ESP new or used? they are both USED
2) Are all UEC fuses and relays from the new UEC or the old one? they were both checked and interchanged
3) did you remove the old and add the new ESP and UEC using Tech2, or did you just swap in new ones? yes, and SPS
4) Can you still talk to ECU? <--- sounds redundant, but humor me here - yes. but NOT when it wont start. then it will not. This issue is intermittent, he can sometimes get the car started, but it will randomly die out while running. I suspected wiring etc was getting hot and flexing at a break.
5) Have you reset the ECU with Tech2? By pulling fuse 2 in the UEC? By disconnecting battery? yes , yes , yes
6) Is the car currently starting or cranking without bypassing main relay? in the instances it wont start, it will not even crank, which made me initially suspect an abs issue
7) Have you looked for any other connectors which may have come off during all this work? as far as i know he has.

What I have to do in situations like this, so I don't get too confused, is ask myself these questions:
What was the last thing I changed or modified? the uec in his case
Have I changed only one thing at a time before making measurements or observations? yes
Do I have a single failure or multiple failures, perhaps acting in concert so they look like something else? i believe it is a single failure causing multiple failures due to the wiring and bus communications of how the car is set up
What is it that I am actually seeing from my instrumentation?

Sorry about the long reply, but in an extended ordeal (for you) like this, it's a good thing to periodically pause, summarize everything, and rethink the issues.
 

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Yeah, thanks!

So, 4 possibilities (if the problem is not dead or dying TCM and/or ECU):

1) P-bus between TCM and UEC
2) P-bus between TCM and ECU
3) Internal bus connection or connector in TCM
4) Internal bus connections or connector in UEC <-- also goes to AHL (also had a problem?)

With ignition on when engine dies, can you light signals, headlamps, so you have an idea UEC is working OK? If the Tech2 snapshots above are still what you're getting, UEC-TCM area is most likely.
 
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