Hi all- I just bought this all stock 2002 GMC Sierra 4WD Crewcab shortbed (98K) beautiful truck, like new. All was well for a couple weeks, then transmission started acting funny. It would not shift up, can only get to 40 mph @ 2500 rpms..indicator lights quit indicating gear selection. I read up on problem on internet and said it may be low battery voltage. Charged batteries and it seemed to make problem go away, and eventually had batteries checked and replaced one of them. A week later problem is back. Just Replaced NSBU switch today without any change. HELLPPP!!! Codes 0700 and 0708 show up.
Allison 5sp: Transmission will not shift, indicator lights not working
- Thread starter DavefromOhio
- Start date
You need to get a higher quality scanner that can see the TCM to see what the P0700 code is. p0700 is just the ecm code saying the tcm has a code(s)
Sounds like he has something that can read the TCM - P0708 is a TCM code - Transmission Range Sensor Circuit High Input. Is the NSBU properly aligned? If so, there may be a harness issue.
Sent from my 831C using Tapatalk
Sent from my 831C using Tapatalk
I was very careful to leave alignment tool in while installing, made sure nothing turned. It acts as if I never changed it out. I took it for a test, it will go to 40 mph @ 2500 rpm. I drove it about 4-5 miles and just as I was turning into drive way the indicator lights on dash came on indicating it was in drive. parked truck, turned off and started again, gear indicator light did not come back on, second test drive...same as first except indicator lights did not come on this time.
I forgot to mention, when changing out nsbu switch, the bigger plug had a lot of what looked like transmission fluid inside plug when I pulled it out. I dried it off before installing new nsbu switch.
Update- I went out and bought a code reader. Hooked it up and it gave code p0708- (transmission range sensor A Circuit High). I erased all codes to see if that would make a difference. I started truck up and without even putting truck in gear the check engine light came on. Shut truck off and plugged in code reader, again it read P0708. Any ideas?
As Mike L. already stated "Loose internal filter can throw the 708 code. ":thumb:
