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1997 855 T5 ECU 850 1997

posted by  Stormie on  Sat Sep 19 23:08 CST 2020
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last visit: Mon Nov 4 14:12 CST 2013
[RELATED]

180,000 mies and I have owned it for six years. The car wouldn't start about two weeks ago and I had a P0120 code = TPS was bad. I replaced the TPS and it did not start. No psark, so I replaced the coil, still not start. I replaced the cam position sensor and still no start.

It's got to be either the ECU or wiring harness. The last three digits on the ECU are 331 and I have been unable to locate one.

Can anyone recommend a company that will repair / remanufacture my current ECU? I live in California, but any recommendations are much appreciated.

Thank you








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    1997 855 T5 ECU 850 1997

    posted by  B.B. on  Tue Sep 22 14:40 CST 2020
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    last visit: Mon Oct 6 13:15 CST 2014
    [RELATED]

    Did you clear all the codes with the new sensors.

    Do you get spark now?

    Bill








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      1997 855 T5 ECU 850 1997

      posted by  Stormie on  Wed Sep 23 12:28 CST 2020
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      last visit: Mon Nov 4 14:12 CST 2013
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      Reset codes and still no spark. I'm having a tough time locating a used ECU. I am still searching for a repair facility for my current ECU. Any ideas??








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        1997 855 T5 ECU 850 1997

        posted by  KlausC on  Fri Sep 25 13:55 CST 2020
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        last visit: Fri Oct 24 10:15 CST 2014
        [RELATED]

        Is fuse #1 blown? 10amp.
        --
        Keeping it running is better than buying new








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          1997 855 T5 ECU 850 1997

          posted by  Stormie on  Sun Sep 27 22:17 CST 2020
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          last visit: Mon Nov 4 14:12 CST 2013
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          Thanks for all of the recommendations. I took my car to a local independent Volvo mechanic for help, as I am at the end of my rope. I thought about "fixing it" with a can of gas and a match, but decided to invoke a little more patience.

          Thus far, the ECU or wiring harness seem to be the problem(s). No spark and the tach moves slightly when cranking. All fuses were verified as good.

          Finding a used ECU in the boneyards was unsuccessful due to different engine types and ultra low emissions requirement for my communist state of California.

          I'm going to have the ECU tested and repaired, if required. If it's a "no go" after that, I will replace the wiring harness.

          I'll reply back as I learn more. I greatly appreciate all of the input.








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            1997 855 T5 ECU 850 1997

            posted by  B.B. on  Mon Sep 28 14:35 CST 2020
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            last visit: Mon Oct 6 13:15 CST 2014
            [RELATED]

            Did you get +12VDC to the powerstage with the ignition switch in the "Run" position ? See previous post.







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              1997 855 T5 ECU 850 1997

              posted by  Stormie on  Tue Oct 27 20:26 CST 2020
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              last visit: Mon Nov 4 14:12 CST 2013
              [RELATED]

              BB and KlausC,

              Problem solved! It was the green wire bullet connector to the fuel injection relay, mounted near the fan. I purchased a fuel injector relay and fuel pump relay in preparation for eliminating the no start issue.

              While replacing the fuel injector relay, the green wire was disconnected from the 4 prong connector. I installed the new relay and ensured that the green wire bullet connector is connected to the relay. I wrapped the wires with high quality electrical tape, ensuring the green wire stays connected to the relay. My next trip to the boneyard I will get another connector with better wiring and replace it.

              I bought plugs, rotor and cap and will install those shortly. I also bought a crank sensor, which I will likely install to eliminate potential failure in the future. My coil and cam sensor are new.

              My Volvo guy missed it, as I checked for spark prior to replacing the relays and there was spark. I removed and cleaned the ECU contacts.

              Both of you gentlemen gave me the confidence that I could solve this puzzle, which started with code P0120 and a flashing arrow on the instrument panel.

              Both of your help is much appreciated. Thank you!








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                1997 855 T5 ECU 850 1997

                posted by  hf63 on  Sat Oct 31 18:16 CST 2020
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                last visit: Wed Oct 22 15:19 CST 2014
                [RELATED]

                You have a nice boneyard in California, Rancho cordova.

                info@volvosaabparts.com








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                  1997 855 T5 ECU 850 1997

                  posted by  Stormie on  Mon Nov 2 21:32 CST 2020
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                  last visit: Mon Nov 4 14:12 CST 2013
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                  That's a bit of a "hike" for me, but there is an import yard in Chula Vista (about an hour away) that has been my favorite for 20 years.

                  I'll keep your recommendation on my "hard drive" and visit Rancho Cordova if I am ever nearby.

                  Thanks for the recommendation.








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                1997 855 T5 ECU 850 1997

                posted by  KlausC on  Thu Oct 29 12:53 CST 2020
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                last visit: Fri Oct 24 10:15 CST 2014
                [RELATED]

                Darn, so simple. I apologize for not pointing you to the relay first. That's what happens when my grey matter (turning black) gets confused with coil overs.

                When looking at parts cars, the 850's with SAS pumps have a relay below the battery which is the same as the relay in the radiator shroud - but pickers seldom grab the radiator one any way. Clean the female ends, make them a little tighter and you will good for a couple of more decades.

                The CPS has NO moving parts. It can be easily cleaned and reused. What does happen is the plug gets corroded and that needs to be cleaned as well. So if you want to return the 'still in the package' and save a few bucks...
                --
                Keeping it running is better than buying new








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        1997 855 T5 ECU 850 1997

        posted by  KlausC on  Wed Sep 23 14:49 CST 2020
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        last visit: Fri Oct 24 10:15 CST 2014
        [RELATED]

        ECU failure is extremely rare. Two main causes: flooding or jumping the battery with the polarity reversed.

        Take off the oil cap and make sure the cam is turning??
        Is there spark to the rotor? How old and what kind of wires do you have?

        You could remove the ECU and clean the contacts.

        There are performance shops that claim to boost engine power by 'chipping' the ECU. But there are a lot of Pick & pull junk yards that still have 1997 T5 computers.
        --
        Keeping it running is better than buying new








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        1997 855 T5 ECU 850 1997

        posted by  B.B. on  Wed Sep 23 13:06 CST 2020
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        last visit: Mon Oct 6 13:15 CST 2014
        [RELATED]

        I wonder if any work was done on the engine preceding the loss of spark?
        Can the coil wire be bad?

        Before you go for a CPU (A bad ground can raise hell)
        *
        Then you also can try disconnecting the battery for10 min- that will reset the CPU
        *
        While you're waiting:
        Check for loose, dirty,unhooked ground wires! There'll be one to the firewall
        and another to the head, maybe more. While you're shining up battery connections, don't forget the #10 red to the battery + terminal.
        Use dielectric silicon grease.

        It's also possible that there's fuses and a relay can be the problem.
        I'm not sure that the ordinary 1997 850 manual is OK for your T5
        maybe? What engine management schematic do I use for your car? EZK, Motronic etc?

        Then I can troubleshoot.

        Put your phone nr in your profile, then I'll call you if I find something.

        Bill







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          1997 855 T5 ECU Part 2 850 1997

          posted by  B.B. on  Wed Sep 23 16:05 CST 2020
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          last visit: Mon Oct 6 13:15 CST 2014
          [RELATED]

          I looked at the schematics and used the EZK ignition.

          Check fuse #1 That powers the ignition module with the ignition switch in "run
          position"

          You need +12vdc at the power stage pin #3 with ignition switch in run position.

          Check the ground "31/52" near the power stage.








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