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Thread: 4L80E torque lockup problem
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06-06-2009 #21Registered User
- Join Date
- Oct 2004
- Location
- Sudbury,Ontario,Canada
- Posts
- 13
The transmission used is a 1991 model, could it be wired differently than a 94 & up ? I checked the wiring harness from the TCU to trans at the TCU connector & the 4L80E /4L60E connectors are on the right color wire as shown on the supplied wiring diagram The wirinharness could still be wrong . I will trace each wire to the plugs at each end to make sure they emd up on the right pins.
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06-06-2009 #22Registered User
- Join Date
- Apr 2009
- Posts
- 113
Yes,
A 1991 is wired differently than a 1994-up.
Let me get you some info to help you out, you'll likely need to drop the pan.
Someone may have updated the wiring if it was rebuilt though.
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06-06-2009 #23Registered User
- Join Date
- Apr 2009
- Posts
- 113
Sorry 1993 up is the break, 1994 they went to a different force motor and torque signal circuit.
Here's the info:
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06-06-2009 #24Registered User
- Join Date
- Oct 2004
- Location
- Sudbury,Ontario,Canada
- Posts
- 13
Jake, correct me if I am wrong but the early trans had a different connector altogether. My connector is as shown on the wiring diagram for the 1993 model. Also would the rest of the transmisions performance be affected ? Everything but lockup works really well , the transmission was rebuilt & as far as I know the wiring was not changed. One last thing if the wiring was wrong I would probably get the wrong resistance reading when I check the TCC solenoid , when I checked it last Thusday it checked out at 10.7 ohms and it should be between 10 & 15 ohms.
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06-06-2009 #25Registered User
- Join Date
- Apr 2009
- Posts
- 113
Yes you are correct, the early connector used a small bolt to hold the harness to it. You must have the newer style harness and connector installed.
So you SHOULD be good. I posted this as a reference for you.
The first rule of actually repairing something is to isolate the problem.
I suspect you have a TCM or tuning issue, but if you can isolate it then you'll know for sure.
The internal harness splits the 12v Ign + to three different solenoids, the A and B shift solenoids and the TCC solenoid.
These all see constant 12v Ign power, they operate on the ground side. So you can ground the TCC solenoid wire and force it to operate independent of the TCM. This will isolate any TCC hydraulics out of the equation.
Then you can use a power probe tool or a LED to watch what the TCM is commanding and see if it matches what you feel.
I just recently did this exact diagnostic procedure on a Furd Exploder that had a weird issue that I THOUGHT was TCC related.
Another rule of thumb for trans work, the one thing you KNOW is OK and are being hard headed about, is what the problem is.
Maybe the diagrams will help, maybe not.
I would at least check the pinout of the TCM harness at the trans end because it differs from the 80 to the 60 and most would ship in the 60 configuration.
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06-07-2009 #26