6l90e won't shift
 

I'm looking for a little info, I've just finished up a 2015 L20 6l90e out of a van swapped in a 88 chevy truck. It starts runs and drives but it will not shift out of first, I'm using the matching engine, e38 pcm, and transmission out of the same van. Any info will be greatly appreciated !
Thanks !

What codes can you read? Sounds like they are not communicating.

Checked fuses for trans? Canbus wires hooked to trans? Fluid good? Trans connectors plugged in good?

The main trans plug is wierd to plug in. Has to twist and lock in place. Had an issue with a swap i did with tht plug. Hptuners couldnt connect to the ecm or tcm bc it was unplugged.

I've checked the plug, and fluid is full. Scanner shows communication and it's not bringing up any codes. My Snap On scanner is showing the shift command up to 4th gear but the transmission never shifts out of 1st just revs out to rev limiter.

Are you getting a tachometer signal? I assume you are getting a speedometer signal. I don't remember what is on the Canbus wires and what is not.

My scanner is showing engine tach signal, trans rpm, speed, gear command. It goes into rev, neutral, and forward but never shifts out of 1st. That' why I'm at a bit of a loss.

Are u using tap shift feature? Shifter works as PRNDM

Im not using the tap shift feature.

Sure your not in M position?

I dont know much about the 6l80/90 trans. There a diff breed for sure.

Yea it's definitely not in M mode.

You said you are running a e38 ecu. Far as i know in 2014 and up they use a e92 controller. It is huge computer. We convert the new engines to use the 2013 and older harnesses that use the e38. We also have to reflash the tcm to match.

Yea it's matching L20, 6l90e, with a E38 pcm out of a 15' express van

I've got a code p2537 to pop up now.

Thats most likely the issue. Says ign voltage to low. Try bypassing the key switch and hook your main ign wire for the ign relay to a toggle switch or something. See how it does thin

code p2537 does not matter :( I always delete it. Do you have the torque converter bolts in??? I think it is something major and simple like that

Yea on the scanner it shows each gear selected ( park, reverse, neutral, drive, and low) just as it should. It also will show the gears being commanded up to 4th before it hits rev limiter. It shows eng rpm, trans rpm, trans temp, and vehicle speed. That's why I'm baffled. This trans had Less than 500 miles before the van was totalled but now I'm wondering if there is something wrong with it internally.

yea that definitely seems weird. May have to open it up.

Strangely, on older GM full size trucks not powering up the second ignition wire (White wire in the main ignition harness) causes a similar issue. Vehicle won't shift out of first. And can cause transmission damage in short order. When I first started installing Remote starters in the early 90's, a few guys I worked with learned this the hard way. IIRC, this wire feeds the transmission.

Bent pin in the trans harness maybe? Good luck!

Jay

Old thread
 

Did you find out what was goin on?