Don't think I am getting lockup.

[rs74]

I am not sure I am feeling the transmission going into lockup. I have tried pressing on the brake enough for me to feel lockup turning off but didn't feel it. The wire is hooked up to the 700r4. What should I be checking.

[chengny]

Without knowing the model year and series of the truck you are asking about, it's hard to go into detail. But generally there are 5 permissives that must be met before the ECM will engage the TCC. The permissives are:

1. Road speed - above 30 mph
2. Engine coolant - above 150 F
3. No undue acceleration/deceleration (as per the TPS)
4. Brakes not applied
5. Transmission in either 3rd or 4th gear

A good place to start might be to verify that the TCC is even functional at all. That's an easy test. Just run a temporary 12 VDC power supply (switched and operable from inside the cab) into the wire that runs down to the transmission.

You can then manually energize the TCC whenever you want and see if it locks up.

[rs74]

It's on my 84 short bed with the 6.2 diesel.

[chengny]

Oh, okay - a diesel. I'm guessing with a 700R4 (2WD?).

Real straight forward. Assuming power available from the fuse block and no wiring issues, there are just 2 permissives to satisfy :

1. Brakes not applied

2. Throttle at least 10% open

Schematic:





Also, to verify that the TCC will operate you don't even have to splice into the power lead. There should be a test connection (orange) under the dash.

It won't have anything connected to it, and should be between the fuse block and the steering column. Run a switched hot wire to it and play around with the TCC. You'll know if it works right away:

[rs74]

Originally Posted by chengny

Oh, okay - a diesel. I'm guessing with a 700R4 (2WD?).

Real straight forward. Assuming power available from the fuse block and no wiring issues, there are just 2 permissives to satisfy :

1. Brakes not applied

2. Throttle at least 10% open

Schematic:





Also, to verify that the TCC will operate you don't even have to splice into the power lead. There should be a test connection (orange) under the dash.

It won't have anything connected to it, and should be between the fuse block and the steering column. Run a switched hot wire to it and play around with the TCC. You'll know if it works right away:

Thanks. I will check the fuses and then run a hot wire to that orange connector. It has been pretty cold the last couple of days so I will wait for a little warm up before diving into it.

[Bigstevex4]

If you have a tach you can see it when it unlocks youl see around a gain in rpm 200 less powerfull eng are real easy you can feel it.

[rs74]

Originally Posted by Bigstevex4

If you have a tach you can see it when it unlocks youl see around a gain in rpm 200 less powerfull eng are real easy you can feel it.

No tach in it. I can feel when they go but this truck isnt going in lockup.