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Back on the road

Discussion in '80-Series Tech' started by sea2skydad, Jan 24, 2004.

  1. sea2skydad

    sea2skydad

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    So I'm back on the road as of Wed.(Jan. 21) and I thought I would post a thread as to what happened. On Thurs.(Jan. 15), the night the site went down, I posted an SOS after having my truck towed home. Some of you may have had a chance to read it but I'll go over it again.

    My truck is a '96 with 100k, that I have owned for 2 months, and after having driven about 150 miles that day, it quit about 20 miles from home. The alt. light flickered, I lost power, couldn't accelerate, and I pulled over. The engine idled fine but sputtered and died when I put in Drive. I did all the checks I could think of at the time, checked fluid levels, checked all drive line components for excessive heat or leaks or burning smells, etc. Nothing obvious. No check engine light. I restarted the engine and while it would die in Drive, it seemed to have no problem in Reverse. Odd, no?

    After making some calls on the cell to some friends, I realized there was nothing else to do but get towed home. The next day revealed an electrical problem. When I got the engine going again, after removing and replacing the EFI fuse, I revved it and smoked the fusible link. Replaced the fusible link ( none were available locally, so I used an inline 20 amp fuse ) and it started perfectly, apparently fixed.

    A test drive up a steep hill caused me to think that I had a fuel delivery problem. The truck idled fine, and revved freely in Park, but died under load. I couldn't make it up the hill and a friend ended up towing me home behind his 62. I PM'ed CDan for advice and possibly parts but he was not convinced that fuel was the issue.

    Monday morning and I admitted defeat and called one of the local autotechs. They couldn't make it till the end of the day and 2 guys showed up at my place at about 4:30. They plugged in the Snap-On reader and there was no communication between the vehicle and reader. At this point there was some head scratching and some rumblings about computer problems. I started to sweat. They tried to start it but couldn't until I pulled the EFI fuse. (small victory) The reader didn't reveal anything. More head scratching. Some basic tests turned up nothing. A brake stand in Drive caused the engine to die, while a brake stand in Reverse did not. At that point something clicked for Noel, the owner of the shop. With the engine running he grasped the main wiring loom between the firewall and where it runs along side the head at the back of the engine. He gave it a good pull and it stalled. He said that there would be one or more burnt wires in the loom.

    Tuesday afternoon and I've removed the EGR modulator, the heater hose at the shut off, the plastic shroud around the loom that holds it to the firewall, and various vacuum hoses etc. I open the loom and Eureka! there are 4 burnt wires and 3 more that are seriously wounded. I attempted to fix using standard heat shrink( Noel advised me not to solder as it makes the wire brittle ) but I wasn't happy with the connection. I bought a pack of butt end crimp connectors that are covered in heat shrink. I dipped the wire ends in a product called Permox, an anti-oxidizing, conductive paste that was reccomended by an electrician friend. I believe there are a number of different brand names.

    The loom was covered in a fibrous tape that offered little or no protection. It then runs into a plastic conduit as it runs by the head. I put a piece of conduit over my repairs and then used some hi-temp aluminized tape over top.

    It works! I have to drive to the Toyota dealer today to pick up the fusible link, then I'm done. I've left a pack of connectors, some wire and crimpers in the truck toolbag.

    When you do a brake stand in Drive the top of the engine torques signifigantly. This puts strain on the wiring harness at the exact spot the wires failed. Another inch of slack may have made the difference. In Reverse the engine torques the other way and there is no strain on the wires. The dead short in the wires caused the fusible link to fail exactly as it was intended to thus avoiding a possible wire fire.

    I apologize for the length of the post, but I thought that it may help someone, someday with their diagnosis. A search of "wiring" turned up some potential problems by Beowulf but nothing specific. I'm hesitant to offer unsolicited advice but you may wantto check your toolkit for some wire and connectors or just some electrical tape and it may just get you out of a bind. Cheers, Greg.
     
  2. Asiarider

    Asiarider

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    Thanks for the infos and glad that you are on the road again. I think it is important to know what can happen even if we all hope that nothing will be wrong with our rigs.

    Mike
     
  3. e9999

    e9999 You want to do what...? Moderator

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    whoah!
    that's good detective work!
    congrats on a good job
    E
     
  4. landtank

    landtank SILVER Star

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    This sounds vaguely familiar from a post about 6 months or so ago. Anyone remember that one?
     
  5. Beowulf

    Beowulf

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    The engine wiring harness has been suggested as a potential problem a number of times:

    https://forum.ih8mud.com/index.php?board=2;action=display;threadid=8173;start=msg69259#msg69259

    https://forum.ih8mud.com/index.php?board=2;action=display;threadid=8983;start=msg78501#msg78501

    https://forum.ih8mud.com/index.php?board=2;action=display;threadid=8983;start=msg78049#msg78049

    The "problem" manifests in different ways depending on which wires are involved. Sometimes it is a failure as the engine torques, sometimes it's a dead cylinder as the FI doesn't fire, sometimes it's an intermittent missing. This harness has been the culprit on a fair number of vehicles; usually those in hot climates and with some age on them.

    -B-
     
  6. Riley

    Riley

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    This suggests to me that we should be periodically inspect the harness for wear and aging due to heat. That's something I would have never figured needed inspection.

    Add it to the list for the anal types. ::)

    riley
     
  7. wob

    wob

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    [quote author=landtank link=board=2;threadid=10576;start=msg94968#msg94968 date=1074974625]
    This sounds vaguely familiar from a post about 6 months or so ago. Anyone remember that one?
    [/quote]


    Umm, yes. The same exact thing happened to me. :(
     
  8. Beowulf

    Beowulf

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    Riley,

    Though I haven't done this myself, it would be a good idea to be proactive and cover the harness area around the EGR valve with some heat resistant insulation. Inspecting isn't easy as the problem occurs internal to the harness.

    -B-
     
  9. IdahoDoug

    IdahoDoug

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    Excellent detective work and thanks for the informative post! When I did all my heater hoses (17!), I had to remove this wiring bundle for access and put new insulation and metal tape in that area. I think one nice day I'll pull that metal tape off and rewrap the bundle with some tough plastic.

    DougM
     
  10. landtank

    landtank SILVER Star

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    Just tacked it on my to-do list when the head comes off in March.