08 Sierra 4l80e t42 issues

[2007chevy5.3l]

Hey guys,

We just did a swap on a 08 Sierra from a 60e and used a 05 4l80e. We followed the wiring diagrams that showed where to repin connectors and add the new ISS plug. Triple checked everything and all looks fine. We had GM flash a 08 Express van tune into the TCM and the truck runs and shifts fine. The issues we are having is we have no speedo, the ABS and Brake light is on. What could be the problem. Is it tune related or wiring?

[ScarabEpic22]

Interesting, I dont know unfortunately.

IMHO it would be easier to run the stock 60E TCM OS and swap the 2-3 wires on the trans plug side to control the 80E with the factory 60E OS. Thats my .02, with the LS1 PCM it wasnt as difficult, the newer stuff doesnt like mismatched pair (life would be so much easier if GM had standardized their ECM<->TCM comms for all makes/models/years).

[2007chevy5.3l]

Interesting, I dont know unfortunately.

IMHO it would be easier to run the stock 60E TCM OS and swap the 2-3 wires on the trans plug side to control the 80E with the factory 60E OS. Thats my .02, with the LS1 PCM it wasnt as difficult, the newer stuff doesnt like mismatched pair (life would be so much easier if GM had standardized their ECM<->TCM comms for all makes/models/years).

I think running the 60e OS with the 80e has problems with TCC lock up.

[joecar]

I think running the 60e OS with the 80e has problems with TCC lock up.

The 4L80E TCC PWM signal can't be directly driven from the 4L60E TCC PWM signal...

it hss to be driven form one of these:
- 4L60E TCC ON/OFF signal,
- 4L60E TCC PWM signal going thru a relay gated by the 4L60E TCC ON/OFF signal.

[joecar]

The other difference is the 4L80E 2-3 Shift signal has the inverse sense of the 4L60E 2-3 Shift signal.

Also the 4L80E has no 3-2 Control Signal.

Also, the truck 4L80E and 4L60E trans segments unlock the TCC on zero throttle, the car 4L60E trans segments keep it locked (GTO).

[2007chevy5.3l]

The 4L80E TCC PWM signal can't be directly driven from the 4L60E TCC PWM signal...

it hss to be driven form one of these:
- 4L60E TCC ON/OFF signal,
- 4L60E TCC PWM signal going thru a relay gated by the 4L60E TCC ON/OFF signal.

I see, so sticking with the 80e OS is a better idea.
Any reason why we arent getting a speedo signal?

[joecar]

Did you check that the VSS sensor produces an AC voltage...?

[2007chevy5.3l]

Did you check that the VSS sensor produces an AC voltage...?

What is the correct way on going about that?