Archived trans problem

[DCreed]

I have a 97 auto 4x4 and the trans has been in and out of the shop a couple times now and now they are baffled. the truck is throwing no codes and will drive in 1st/reverse only if on the throttle, as soon as you let off the pedal it goes into "neutral" and wont move again. it has good fluid, no junk in the pan and no codes. what could it be? I'd hate to get a trans and find out it was a pcm or a sensor! this is my work truck for plowing and it is snowing like crazy and the truck is down! Please help!

 

[Missouri Mule]

Could there be something wrong with front band or its components/valve body.



The front band controls shifting for 1,2,3 and 4. looking at book this is when slector is in drive.



Rear band controls first and reverse don't know if this in drive on when first is selected.



Just found this is in the service manual.

First an reverse only. no up shift 1-2, 2-3... .

1. Governor valve. shaft, Weights or body damage/stuck.

2. Valve body malfunction.

3. Front servo/kickdown band damaged/burned.

 

[Joe G.]

The front band only grips in 2nd. In all other gears the front clutches are holding so the truck should move in 1st manual even if the front band is not working. I think it has to be a VB or PCM problem. Has the shop done any pressure testing? If the oil pump was bad so your line pressure was really low it would act like that.

 

[DCreed]

Thanks guys. Yes the ports were pressure tested and the #s were good, IIRC 230psi and spec called for 160-310?