e38 4l80 swap 07 silverado cant get speedo to work???

[MN C5]

The Speedo, BCM & TCM need to have compatible OS's. I believe the Speedo gets its signal from the BCM, I had it a bit easier swapping a 6L90 because I was able to use a factory harness from a HD2500 that came with the 6L90.

And even if the connectors are the same it doesn't mean that the leads back to the BCM have the right connections. My guess is if you trace the wiring back to the BCM from the speedo you'll find the issue in the wiring or OS's.

Good Luck

[gmh308]

it is a 07 silverado, had a 5.3 and 4l60 in it, not swapped into anything

built 440lsx with nitrous and 4l80 in it now

harness is from speartech

they offer no tuning support

when connected to the tcm with a modis you can see speed and rpm ect, nothing on dash works tho.

the wiring part seems to be intact. if we get the tcm programed at a dealer with a 4l80e tune for a t42 will it work on the gmlan to communicate with the ecm??

thanks

Ok gotcha now. If you get a 4L80 tune into the T42 that sends speedo on the GMLAN it "might" work. Depends on whether the TCM tune is compatible with the ECM where it needs to be. Other choice is I can send you a tune that expects the speedo input direct and routes the VSS PID correctly, to try out.

[b18cls1]

anythings worth a try

[gmh308]

anythings worth a try

Ok...if you are interested PM your email address through.

[b18cls1]

pmed

[DURAtotheMAX]

IIRC the only GMT-900 application that used a 4L80 from the factory was the 07-08 2500 suburban. See if you can find a T42 calibration from an 07-08 suburban 2500 and I bet that will work.

[DURAtotheMAX]

any updates?