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88 MJ auto won't shift...


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Brand new TPS properly adjusted didn't fix it. Everything I can find around the trans is plugged in on both ends. Even tried replacing the fuse and still nothing... Trans is full of fluids. It moves fine in 1st and reverse on the selctor. If you put it in 3rd or OD, it hardly moves. You can feel it click into first, but after that it's revving up and hardly moving.

 

Been working on this for the past 2 days now and still can't figure it out... I adjusted the TPS off the 3 prong connector. I could not get a reading out of the 4 prong connector.

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Are you trying third and overdrive on the road, at legal speeds, or from a standstill in the driveway? Don't forget, if you're trying to test it while parked in the driveway it's the same as trying to start up a vehicle with a manual transmission in fifth gear. Not recommended.

 

One of the troubleshooting routines for the AW4 is to remove the fuse and drive it by shifting manually. That should work -- except there's no second gear. If you can drive it like that, you may need a transmission control box.

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Brand new TPS properly adjusted didn't fix it. Everything I can find around the trans is plugged in on both ends. Even tried replacing the fuse and still nothing... Trans is full of fluids. It moves fine in 1st and reverse on the selctor. If you put it in 3rd or OD, it hardly moves. You can feel it click into first, but after that it's revving up and hardly moving.

 

Been working on this for the past 2 days now and still can't figure it out... I adjusted the TPS off the 3 prong connector. I could not get a reading out of the 4 prong connector.

 

No reading out of the 4 prong connector is the smoking gun here. That's the side for the trans. Can't find power at that connector at all? There's the issue.

 

Try this:

 

Cruiser’s Trans Plug Refreshing

 

 

Over near the trans dipstick tube are 2 rather large connectors. One is black and the other gray. These 2 connectors carry all the info between TPS, TCU, NSS, speed sensor, and trans solenoids.

Unplug each one, visually inspect for corrosion or bent pins, spray them out with electrical contact cleaner and plug them back in.

 

Revised 3-28-2012

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  • 3 months later...

This is the fun part... Those connectors are hiding. The previous owner must of done one hell of a jacked up swap or something.

 

I've driven it around town a bit and it does ok when you shift if manually. Last night I took it up to highway speeds and now the trans slips and leaks when it didn't do either before.

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Which fuse did you replace?

 

7.5 TRANS in fuse block?

 

or

 

15 A under dash, PASSENGER side by the TCU?

 

You beat me to it, Quickdraw.

 

That's certainly suspect.

 

As is the ground at the engine dipstick tube stud which grounds the TCU and may be why there's no reading at the 4 wire connector.

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