Ive had my truck up and running on the new setup for about 9 months, no issues at all. I jump in the truck to make a 700 mile round trip, i start getting crazy shifts : up shift then down shift problems at cruise. No SES light unless i stomped it to throw the p0700 code. I drove home 2.5 hours this a.m with 4th gear only.


From the start of the morning:
I had a immature p1761 that morning with the p0700. I figured it was bc of a bad battery since it was 45* when i started my trip and i dont drive my truck very often. I got where i was going with this up shift down shift issue only happening a few times. I put a new battery and drove for about an hour with no issue. Raced my truck about 6 times with no issues either. I start my drive home and about 45min into my trip the truck starts going crazy and would not give me a SES light unless i floored it. I finally got the p0700 and it drove in 4th gear with no issues the rest of the trip. I made it home with good transmission temps and with a truck that i didnt set on fire on side of the road lol. I woke up and grabbed the laptop to see what codes i had, well i had a bigger list this time

P0700 immature
P0700 current
P1761 immature
P2534 immature
P2534 current

I pulled the tcm harness and checked the pins nothing was broken, melted, crushed. I peeled the tape and checked the harness about 1' up onto the trans, nothing wrong. Wrapped it all back up, zip tied everything shut in the loom and zip tied the harness to the trans to stay off of my exhaust. I didnt drive the truck after this bc i was annoyed with it.

The thing i cant understand is i drove it thursday, friday about 1200 miles total and had a few 100 mph punches to make sure it was strong enough to make my next 700 mile trip. The truck had no issues starting, killing, staying running. Saturday comes and i have issues 1/4mile from my house then nothing the rest of the trip till its time to come home. I have a dashhawk in my truck but it dont show the other codes other than the p0700.



Any help would be great, THANKS. I havent done anything to the truck since i installed the 6spd an brand new GM harness/ECM in December. Im leaning towards an ignition switch bc the truck runs great when the codes arent there.

 

PO700 TCM requested MIL illumination-- code sent from tcm to pcm
1761 tap shift incrment counter does not match from tcm to bcm
2354 Ignition 1 switch circuit voltage low.

Replace ignition switch and you will be good to go I bet.

 

Thanks man, we were thinking it is the ignition switch but wasnt certain.

The tu/td switch is invalid for my truck bc i dont have it working

 

I think it's actually pretty easy to make it work if you want to do it sometime.

 

Swap to a newer 6 speed bcm reflash it for a sierra denali and run an additional wire from the lever to the bcm and you are good to go.

 

My bcm harness has the 2 wires for the TU/TD in my shifter. I didnt want to risk anything to i just made my own way of selecting what gear i want

 

no risk if you ever want to do it in the future wham bam thank you maam working tap shift. Just use 2008 denali BCM and VIN for bcm radio etc and you are good to go.

 

seems easy...lets just hope the ignition switch fixes my problem

 

i need someone to do that to my truck i want the tap shift to work
so we need the denali bcm?im still on oem harness...i may need the whole harness for 6 speed i bet
hope u get it back to 100% Ken

 

Zach what do you mean you are on the factory wiring harness? You didnt swap to a 6spd harness?