4l80e no shift (limp mode?)

[txarkitekt]

Looks like to be a wiring issue--not mechanical--between the TCC PWM and the TCC.

First thing I would do is check the TCC solenoid ignition feed circuit fuse from instrument panel fuse block. Is it good?

If so, then I would drop the pan, turn the key to the ON position, grab an Ohmmeter and make sure that you have 21-33 Ohms of resistance from the fuse block to the 20 pin connector on the outside of the case...and then into the corresponding wire on the trans' internal wiring harness. Then remove the TCC solenoid and check resistance at the TCC connector. Still have 21-33 Ohms? If so, the solenoid is bad.

[RedHeartbeat]

Start with the simple stuff, see that you have 12v at the transmission. If your brake light is on the power would be off at the transmission. Is this a stock vehicle with 80e or is it a retrofit? Check your PCM grounds going to the engine block, one loose or broken will prevent it from shifting. Power and ground are most often the issues. If no power then there may be something wrong with your brake switch or have blown a fuse, check them all.

How did you rewire the transmission for the 80e? did you use an adapter or relocate wires? 60e wiring stock configuration will not work on an 80e without being modified. Do you have signal from the input speed sensor going to the PCM?

[noahd]

Start with the simple stuff, see that you have 12v at the transmission. If your brake light is on the power would be off at the transmission. Is this a stock vehicle with 80e or is it a retrofit? Check your PCM grounds going to the engine block, one loose or broken will prevent it from shifting. Power and ground are most often the issues. If no power then there may be something wrong with your brake switch or have blown a fuse, check them all.

Hi Red-

This is a project truck. It's a 50's military dodge powerwagon, frameup rebuild. The relevant wiring is the injection tech wiring harness. I will triple check all my grounds though. There are only four fuses involved (five counting the brake/tcc switch), all are good. The brake switch is brand new and I've tested both the brake switch and the TCC switch part of it, both are working as they should. There is no corrosion to speak of as it's been garaged since the frame up resto, but like I said I'll triple check my grounds.

**edit:

I didn't note which pin #s they were, but I ran through each hole on my tranny plug on the wiring harness (with key on) and I remember there being one with 5v and one with 12v.

I will be checking the resistance on the TCC PWM solenoid as mentioned above.

[noahd]

Looks like to be a wiring issue--not mechanical--between the TCC PWM and the TCC.

First thing I would do is check the TCC solenoid ignition feed circuit fuse from instrument panel fuse block. Is it good?

Yes, double checked those connections, all 4 wires/fuses (per my aftermarket harness) are getting 12v.

If so, then I would drop the pan, turn the key to the ON position, grab an Ohmmeter and make sure that you have 21-33 Ohms of resistance from the fuse block to the 20 pin connector on the outside of the case...and then into the corresponding wire on the trans' internal wiring harness. Then remove the TCC solenoid and check resistance at the TCC connector. Still have 21-33 Ohms? If so, the solenoid is bad.

Ah! Thank you. I will check this. Thanks for some direction.

[txarkitekt]

Ah! Thank you. I will check this. Thanks for some direction.

No prob man. Hopefully you can get it all worked out.