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Yaj's avatar
Yaj
Explorer
May 08, 2013

1996 Frieghtliner Transmission 12V power question?

Hello all!
I have a issue that came up about 500 miles from home.
While cruising homeward bound my 3060 transmission started acting up.
First it lost all indicators on the touch pad, the speedometer went dead and it wouldn't shift. It seemed like it was in 5th gear with quite a wide rpm range. Then it cleared up.
Within 50 miles I stopped to dump my tanks, shut down engine. Then I started the engine and right away it did the dead thing again and also showed "do not shift" on the dash. I pulled over out of the way, shut down, and the engine would not start again. It showed the "do not shift" on the dash, and clicked under the dash, but no joy.
I figured since the touch pad was dead that the transmission wasn't telling the engine, hey I'm in neutral so you can start.
I checked the obvious, and after much head scratching, I opened the Allison box with the 6 relays under the dash. It has 2-10 amp fuses in it, one labeled "Main Power" the other not labeled, both fuses good. The main power fuse did not have any power regardless of what I did, But the other fuse would show 12V with the key on. I tried swapping all the relays around and I got nothing. I finally supplied 12V from a different source (with a 10 amp fuse inline) to the fuse labeled Main Power and I have JOY!
We made it all the way home without further incidence, I disconnected the alternate power source whenever we stopped. And I am about to start trouble shooting it.
I think it my be a bad relay under the dash as there are several tucked way up where they can't be seen, only felt by hand. One or more does click when I turn the key on.
I thought before I started trouble shooting I would bounce it off the minds here to see if I'm going in the right direction.
I offer a early thank you for any thoughts you guys might have.
I will check back in about a hour. And I will post to this thread the outcome for all to gain from!
Sincerely,
Jay Herte
Class A

9 Replies

  • Jay58's avatar
    Jay58
    Explorer
    May 11, 2013
    Jay, Jay here, when you have time please e mail me the Allison wiring diag. One day I might need it.
  • gfs1943's avatar
    gfs1943
    Explorer
    May 10, 2013
    Thanks for posting the solution. It really helps all of us when posters come back with the details of what fixed the problem!
  • Yaj's avatar
    Yaj
    Explorer
    May 09, 2013
    The wiring diagram showed that fused wire from the battery as the feed to the Allison box, so I started from that end.
    Another 2ft into the engine compartment, behind the air cleaner, there was another crimped connection. It was so corroded that it fell apart as soon as I got to it. No test light necessary! It fell apart as soon as I touched it!
    The wire has been striped back and re-crimped and sealed. Good to go!
    Thanks again everyone, the fellowship here is just great!
  • Yaj's avatar
    Yaj
    Explorer
    May 09, 2013
    I found the fuse located by the battery when we were on the road and it checked out good, but today I double checked it and yes it is/was good (power in the wire after all connections and fuse) but what gave me the opportunity to clean everything including the battery connections. Everything shiny and properly protected now.
    So, I still have no power to the Allison box. I'm going to try to trace backwards from there.
    I should be receiving the wiring diagram from Freightliner in the next couple of minutes, so that should help. Freightliner was really nice and tried to be helpful, and offered up the diagram as soon as asked.
    I do have a test lamp wired in so that will save a lot of trouble some checking. Easy to hang the light out the window while I was checking around the chassis battery.
    Thanks for the phone number and all the helpful suggestions.

    Update at 11, or before if/when I find the issue!
  • fcooper's avatar
    fcooper
    Explorer II
    May 08, 2013
    Suggest you call the Freightliner help desk 1(800) 385-4357 and have the last 6 digits of your vin number available. They will have access to the wiring diagram for your coach. You may be able to get them to print and mail one to you. They've been very helpful for me.
    Fred
  • MrWizard's avatar
    MrWizard
    Moderator
    May 08, 2013
    gfs1943 wrote:
    Look for a tranny power wire near the batteries, with an inline fuse. Some coaches have that setup that powers the transmission computer. If you have it, you will find a wire connected directly to the battery positive terminal, with the inline fuse nearby.

    yep our Safari with 6 speed Allison trans has an inline fuse at the chassis batteries
  • wolfe10's avatar
    wolfe10
    Explorer
    May 08, 2013
    Good advice so far. You can contact Freightliner with your chassis serial number and they can tell you where that wire gets power.

    BTW, good job on troubleshooting to keep rolling.
  • gfs1943's avatar
    gfs1943
    Explorer
    May 08, 2013
    Look for a tranny power wire near the batteries, with an inline fuse. Some coaches have that setup that powers the transmission computer. If you have it, you will find a wire connected directly to the battery positive terminal, with the inline fuse nearby.
  • boogie_4wheel's avatar
    boogie_4wheel
    Explorer
    May 08, 2013
    You did what I would have done; jumper power to fuse and get it home.

    Back trace wire from dead fuse to wherever it goes. I would assume it is a keyed-source as well, but I haven't dealt with the Allison-World controller enough to tell you exactly what it needs. Could be a relay or a loose connection (plug, crimp, loose terminal).

    Wire in a test lamp to that dead fuse, then as you're shaking and tapping on things you can watch for the light to flicker on. This will help notify you that you are close to the issue. Don't forget to have the key turned on.

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