4l80e no shift (limp mode?)

[noahd]

Hello all,

I am picking back up a project truck I was working on a few years back and am running into some problems with my 4l80E not shifting.

The setup:
-Vortec 5.7L
-aftermarket wiring harness from injection technologies
-PCM flashed by Centech for the 5.7L/4l80E (supposedly...)
-4l80E

The problem:
The tranny will not shift and acts the same regardless of whether or not the main tranny plug is connected or not. It has reverse and what feels like 2nd gear. Could be 1st. I think I've checked the wiring for anything stupid, all the pins in the main harness match up and look like their connecting, both speed sensors have been swapped and are plugged in, I tested the TCC PWM solenoid and the B Solenoid and both appear to work (on the bench). I've also tested resistance on the PWM solenoid pins on the main tranny plug and it appeared to be fine.

It throws codes of P1860 and P1864.

I'd like to be able to rule out a computer issue and focus on the tranny/wiring or know that I need to get the PCM reflashed (or maybe I have a bad one-- but the engine runs pretty good??).

Anybody have any pointers?

Thanks for any help.

[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]

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.

[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.

[DBRODS]

Sounds like to me your 80E patch file wasn't done correctly. HP tuners can rewrite the tune to accept the 80e or you can get something that came with the 80e and patch in the motor file. I've seen this a few times... Sounds exactly like whats happpening. Also with it in drive does it feel like it has like a 6000 stall....LOL

[noahd]

Sounds like to me your 80E patch file wasn't done correctly.

Ugh.

Which brings me to what might be my next question: if I decide I need to get my computer reflashed, who should I send it out to? If I remember correctly, a few years back this computer was flashed to delete the extra 02 sensors behind the cat, anti theft, all that extra fluff stuff.

[txarkitekt]

Sounds like to me your 80E patch file wasn't done correctly...

Yes, good call Jon!!!

Ugh.

Which brings me to what might be my next question: if I decide I need to get my computer reflashed, who should I send it out to?

Nelson Performance. While it's there, have Nelson flash you a good tune on there so the L31 doesn't seem so sluggish in front of that 80e in that badass Powerwagon!

[WARLOCK]

Nelson Performance - Performance without Sacrificing Drivability FTW