04 ISX wont rev. Many codes

Discussion in 'Volvo Forum' started by Slow302, Mar 19, 2014.

  1. Slow302

    Slow302 Medium Load Member

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    Well long story short two nights ago while i was driving something derate power for split second and speedo goes to 0 but power come back. Happened about 5 times that night. In the morning got worse but i cept driving. Then i stopped to get some fuel and then i started truck but there is no revs. It will idle but accelator wont work. I checked bunch of wires under the hood where i had same problem last year, green wire, both twisted pairs nothing. Resistance is good on those wires from firewall to ECU so no bad wire there i think. Than about 2 hours later for no reason i got revs back. Since then i put about 1000 miles without shutting truck untill i needed some fuel. Same thing again.
    Codes i have are

    Engine ECU
    Sae J1939 data link Communication error MID 128 SID 331 FMI 9
    Vehicle speed Data erratic MID 128 PID 84 FMI 2

    Brake ECU
    SAE J1939 data link communication error MID 136 SID 231 FMI 9

    Vehicle ECU
    Cant read any codes Operation failed

    Climate ECU
    SAE J1708/J1587 data link Communication error MID 146 SID 250 FMI 9

    Light Control Module
    Data Link SAE J139 MID 144 Communication error MID 216 PSID 201 FMI9

    So AC wont work. Running light are on truck soon i started. After shutting truck i dont hear fan seleniod shut off fan for some time (use to be right away). Truck ABS stays on. I can drive on idle and shift gears (13 speed) but looks like speedo doesnt work

    I would burn this truck but i cant since i have spend $16k on overhaul 3 months ago
    For some reason i think VSS may be bad (i have only one) but laet time when i change VSS becauze speedo dint work there wasnt deratting power just speedo stayed at 0
    Anyone got any ideas
     
    Last edited: Mar 19, 2014
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  3. gpsman

    gpsman Road Train Member

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    I had a 2004 ISX whose engine ECU once replaced sometimes didn't last 1 mile. I'd pick it up at the shop, all good, 30 seconds later the gauges are going nuts and I didn't have enough power to top 50 mph. I think that issue was not uncommon. If there isn't a recall, there probably should be.
     
  4. CondoCruiser

    CondoCruiser The Legend

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    You can guess all day until they hook the laptop up. Guessing is more expensive. But my guess is the VSS, vehicle speed sensor mounted on the transmission. With it bad the speedometer can't function and the ECU can't calculate and goes whacko. The VSS wiring could be bad too. There are many other things it can be too. Just guessing.
     
  5. jameslawton

    jameslawton Light Load Member

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    Data link error will shut every thing down there are at least 5 computers and two resistors that will cause that plus broken and loose wires
     
  6. Slow302

    Slow302 Medium Load Member

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    Like i said i was thinking bad VSS but last time when VSS wae bad like 4 years ago i was able to drive it with full power, just cruise and speedo didnt work. But this time all i can do is start the truck and idle and if i want idle around the truck stop !!!
     
  7. Slow302

    Slow302 Medium Load Member

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    Anyone know where twisted green and yellow goes from firewall to under the dashboard.
    And also where two sets of all black twisted pair wires goes from firewall under the dash
    I see many 2 pairs if green/yellow, one pair goes to LCM other pair goes to VECU, also one pair where diagnostic port is.
    Black twisted pair i have found goes to VECU
    Are these same twisted wire that are on firewall and they Y in many directions or what?
     
  8. Slow302

    Slow302 Medium Load Member

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    Also where those two wires from VSS goes to. To the ECU or to VECU ? I want to check ohm on those weris but dont know where they goes to?
     
  9. Slow302

    Slow302 Medium Load Member

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    Well i trace those 2 wires from VSS. They are marked 500 and 501. Thet go from VSS over left side frame rail into connector than thru floor by driver seat and than under carpet and they go up next to fuel pedal. So far those two wires are good to the dashboard. Im gonna try trace them more
     
  10. Slow302

    Slow302 Medium Load Member

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    UPDATE
    Twisted wires 500/501 that goes from VSS to the VECU blue connector are good
    What other wire i should check since everything is apart?
    Thanks
     
  11. Slow302

    Slow302 Medium Load Member

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    UPDATE
    Green wire that goes from ECU thru firewall to VECU and LCM is good
    Same thing for yellow wire. All good
    Twisted 400/401 that goes from ECU to VECU and LCM are good too

    What else???
     
    Last edited: Mar 19, 2014
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