Stuck under a load.10 speed Meritor Transmission will not go into high

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by henboy1, Feb 20, 2020.

  1. henboy1

    henboy1 Light Load Member

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    10 speed transmission on a 12.7 detroit.2003 Columbia.This problem started getting worse.First, I couldnt go in HIGH and then when I am highj , I couldnt go low.Now , all of a sudden I cannot go high.Drove about 15mph in 5th gear to a safe location.Ubered and replaced the whole shift knob which has the cruise etc on top.
    It didnt fix it.Then I replaced the air solenoids and the piston at the back of the transmission(kit).Still didnt fix it.I cranked up the truck and checked the power going to the solenoids .When in High and Low.........No power getting to the solenoid.So I had a transmission guy come look at it.He said the harness was bad.He wants to change . all the harness and a bunch of all other BS like regulator valve , neutral switch and charge $750.I told him no, I only need the electrical part fixed.So, I went to freightliner and bought the 2 harness.I couldnt get the 3rd that goes to the ECM.I dont know what the transmission guys means , but he said the connector going to the ECM needs to be pinned.I havnt looked at it , but what does that mean?Another guys said the schematic for that may be proprietory.I am about to go under there tomorrow morning, but before I go and get this 3rd harness from Richard Kearns , I would like to know how to connect this harness to the ECM.This is definitely a power issue..Please advice
     
  2. BoxCarKidd

    BoxCarKidd Road Train Member

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    Can not tell you a lot about your exact set up but:
    Pin out means to check all the of the pins in a harness to the other end with an ohm meter. Also checking for required voltages.
    While that is all well and good that will not tell you if the wires will carry a load. Connecting them so as to power a sealed beam headlight through each wire is a better test. I have seen a bad harness pass that test but still break down on the road, probably very rare.
    Freightliner has provided me with particular schematics for some circuits. So far as any troubleshooting or other info you are probably on your own.
    Can you get any active codes and report back?
     
  3. henboy1

    henboy1 Light Load Member

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    An active code> This has nothing to do with the DDEC IV engine codes.This is specifically transmission HIGH/LOW not getting power.The check engines I have is unrelated to transmission problem.2003 Columbia
     
  4. henboy1

    henboy1 Light Load Member

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    2 guys had the same problem on this forum but they never reported back for the fix.
     
  5. henboy1

    henboy1 Light Load Member

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    Do you have the schematic for this meritor transmission circuit from the shifter to the ECM connector?
     
  6. BoxCarKidd

    BoxCarKidd Road Train Member

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    Being in a Columbia that is newer than any Rockwell electric over air unit I have ever worked on. Companies wants to put computers on everything anymore, even lawn mowers.
    If you post your vin someone maybe able to help you with the wiring.
     
  7. henboy1

    henboy1 Light Load Member

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    Last 6 of VIN J74378
    I am going to the junk yard tomorrow, not sure if I would still need to pin out a used harness . I just want to see what it looks like and ask the guys at the junkyard on connecting that last harness
     
  8. Working2party

    Working2party Medium Load Member

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    My fleet had a bunch of 2001 meritor 10 speeds in the 2001 FLD’s. Their are no computers that operate it. It needs 2 simple things: good, clean, air pressure and good clean 12v power and ground. The only connections to the ECM are to one of the 2 speed sensors on the tail shaft.

    The air system starts with a 60 psi pressure check valve mounted on the secondary air tank. It only feeds air after the truck has 60 psi. It’s fed to the back of the transmission where it attaches to a 90psi regulator. Then to solenoids. My first check was always to make sure there was air coming out of the regulator.

    I’m not sure where your power starts on your Columbia. So I can’t help much there. And it’s been long enough I can’t remember the schematics. But I do remember we had more issues with the neutral (shift) switch (mounted in the transmission cover) But if you’ve replaced the solenoids and the shifter then you need to check the switch next. If you unplug it and jump across the harness contacts, it should shift. You can limp it home like this, but make sure you ALWAYS HAVE THE SHIFT LEVER IN NEUTRAL BEFORE FLIPPING THE HIGH LOW SWITCH!!!

    If all that fails, hook up your two new harness’s I’m assuming they will connect the solenoids, shift knob, and shift switch. There should be a connector with two pins left. Get them connected to power and ground and get home till you can get the OEM harness.

    Hope this gets you rolling.
     
    25(2)+2 Thanks this.
  9. baha

    baha Road Train Member

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    If its not a auto/ shift trans. The part you need to replace is on top drivers side of trans. follow air lines to find it, It shifts air to hi and low piston on back box of trans. kerns should have it in stock, buy a new one not rebuilt?
     
    henboy1 Thanks this.
  10. Working2party

    Working2party Medium Load Member

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    If I also remember correctly there is a pin in the top transmission cover that has to move freely. One position is when it’s in any gear and another position when it’s anywhere in neutral. That pin is under the neutral switch so try to make sure it moves to identify neutral when/if you remove the that switch.
     
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