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2005 T6 ECM short?

Help, Advice, Owners' Discussion and DIY Tutorials on Volvo XC90s. The XC90 proved to be very popular, and very good for Volvo's sales numbers, since its introduction in model year 2003 (North America).
midi510
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midi510

2005 T6 ECM short?

Post by midi510 » Mon Sep 23, 2019 4:46 am

I was driving my daughter's car to work to replace her front brake pads and rotors when I got off, when it instantly shut down and wouldn't start. I hooked up my Blue Point code reader and got P0442, P0348, P0342, and P1652. The 442 is evap, which I didn't worry about, the 348 and 342 are cam sensor, and the 1652 said manufacturer specific. I looked it up online and found ECM short, which I've found different things subsequently.

I was hoping it was just a cam sensor and looked for resistance values online. I couldn't find anything for her specific year and model and read that the hall effect sensors can't be tested by a simple resistance test. (Hall effect sensors are used on Pisten Bullys and it's true of them.) I read that the three wires going to the sensor are for ground, power, and signal (makes sense) and that there should be 12v on the power wire and 5v on the signal wire. The pin numbers I found online didn't jive with what I found, but I'm sure pin 2 is ground and I was getting 5v on pin one and negligible voltage on pin 3. I found continuity between pins 2 and 3 indicating a short to ground. I couldn't find any bad wiring and figured it was somewhere I wouldn't be able to see, like inside the loom and ran a new wire from the ECM to the sensor plug. I now have no continuity between 1 or 3 and ground or each other, but get 5v on both. Since I read the the 1652 code could be a ECM short I'm thinking the short may have jacked the ECM. I wish I could just replace the sensor, but if I'm not getting the correct voltage, I don't want to waste her money on a sensor. I'm thinking about buying a used EMC, but have now read that it may need to be reprogrammed to her car. It's a good three hours one way to the nearest dealer or shop that works on Volvos. She already bought a new car and just wants to get this one running to sell it. It ran fine before this happened.



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RickHaleParker
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RickHaleParker

Re: 2005 T6 ECM short?

Post by RickHaleParker » Tue Sep 24, 2019 3:14 am

Battery in good health? Incorrect voltages will throw the control modules will cause false error codes. ( Incorrect sensor data. )

Your symptoms and codes have been traced to a dirty MAF sensor. When was the last time you cleaned the MAF?

Air leak or restrictions in the air flow. Dirty Air Filter?


ECM-982A (P1652) Engine control module (ECM). Internal fault. Permanent fault

Diagnostic trouble code (DTC) information ECM-982A

Condition
Diagnostic trouble code (DTC) ECM-982A is stored if the engine control module (ECM) registers an internal fault in one of the internal monitoring functions in the engine control module (ECM). The diagnostic trouble code (DTC) is diagnosed at ignition on or with the engine running.
This diagnostic trouble code (DTC) is normally always stored when one of diagnostic trouble codes (DTC) ECM-983A, ECM-984A, ECM-985A, ECM-986A or ECM-988A is stored in the engine control module (ECM). Incorrect sensor data.

ECM-983A: Calculated engine speed (RPM).
ECM-984A: Calculated load signals.
ECM-985A: One or more present values that do not correspond with the complement value.
ECM-986A: Throttle unit position sensor interpreted as having exceeded their minimum or maximum limits.
ECM-988A: Accelerator pedal (AP) difference between the two signals detected.
( Incorrect sensor data )


Substitute value
None.

Possible source
  • Search for failure cause with another stored diagnostic trouble code in the control module.
    Blocked exhaust system.
    Blocked intake system.
    Air leakage in the intake system.
    Damaged engine control module (ECM).
Fault symptoms
  • Driving/Poor performance/lacks power/At take off
    Idling/Uneven idle
    Driving/Poor performance/lacks power
    Driving/Hesitates/surges/Unsure when/at all times
    Driving/Hesitates/surges/During acceleration
    Driving/Hesitates/surges/During deceleration
    Cruise control/Does not engage
    Driving/Hesitates/surges/At steady speed
    Warning lights and chimes/Malfunction Indicator Light ("Check engine" light) indication/no indication


Platform: P80 1998 C70, B5234T3, AW50-42, Bosch Motronic 4.4, Special Edition package, Plant: Uddevalla Sweden.

Platform: X40 (Nedcar) 2003 S40, B4204T3, AW55-50/51SN, Siemens EMS 2000. Plant: Born Netherlands.

Platform P2 2005 XC90 T6 Executive, B6294T, 4T65 AWD, Bosch Motronic 7.0, Plant Torslanda Sweden.
----------------------------------------------------------------
1997 S90, B6304S, AW30-42, Bosch Motronic 4.4 - Sold

midi510
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midi510

Re: 2005 T6 ECM short?

Post by midi510 » Wed Sep 25, 2019 6:06 pm

Thanks for the reply. I thought I'd get an email notification if someone replied, but didn't, and forgot to check last night.

The car has always had good performance and shut down at 45 MPH on my way to work and hasn't as much as fired once since. It's not like it died, it's like it was shut down - instantly. I think the LCD said something including "immobilizer" when I was on the side of the road right after. It didn't mean anything to me at the time, but now I know what that is. Would it ever shut the car down while driving?

The voltage definitely wasn't low. Would any of the other stuff you mentioned cause the voltage to the cam sensor to be low? Wouldn't there be a MAF code if it was dirty? Even if a sensor goes bad, it doesn't kill the car instantly, right? That could be really dangerous. I'm an A&P and have been working in Pisten Bullys for the last 25 years and it seems like an ECM fault is most likely. I'm going to try some of the immobilizer fixes I've read about, just to get that off my mind.



Kris521
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Kris521

Re: 2005 T6 ECM short?

Post by Kris521 » Mon Sep 30, 2019 6:49 pm

I looked up pisten bully while reading this. I think it's funny, since I broke down this weekend on my first trip in my 05 XC90 2.5, and an old man who lent me a gas can, said he works on them. He tried to help, but he had no idea about this car.
Long story short, if you suspect an ECM fault, check the windshield cowl for leaves and debris. Checking the sunroof drain and cabin air filter seems like regular maintenance on these things, from what I've been reading to understand what actually happened. I bought this a month ago after sitting for who knows how long. Mice, clogged drains, VT salt and sand. I was really worried about ECM, since my codes use ECM as the code prefix. But Rick cleared that up for me. And unfortunately for you as well. My problem will be remedied this weekend, thanks to VIDA. I would recommend you get it as well. Because you can't rely 100% on forums. Let us know what you come up with as a fix. I'm not sure about an ECM, but if a 2007 V8, 3.2 is it? Or a 2004 5 cyl 2.5T would work, let me know and I'll grab them from the junkyard near me. Or if you research XC70's S40s, and anything that might interchange. I'll be there, so whatever they charge plus shipping and I'll see if I can help you out. I'm trying it with a few things before ordering from FCPEuro. Good luck!



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