P0877

Hambone

Always learning
Jan 24, 2016
572
0
16
Florida
The Truck 06 2500 Silverado cclb WT
The Story,
Well about a 2 weeks ago we had one of our tow trucks go into limp mod after making deliveries all day:(
Friend of mine is the company mechanic along with myself when things go wrong.
He hooked up the computer and got a p0877 code which read "Transmission Fluid Pressure Sensor/Switch “D” Circuit Low"
We have had this happen once before on a different rig and replaced the PSM and go about our merry business, unfortunately that was not the case this time.
So he got called out to a job and I was called into the ring :hug:
First thing I do is grab my atsg and start testing For resistance... well everything tested good and I was stumped!:confused:

So I called up the Master Allison mechanic and asked him what he thought:D

And he told me he never heard of a p0877 so I said crap lol!
I told him what it read and he said I had a short somewhere in the wire.
At which point I realized DUH it said "circuit low"

So then came the tracing, after searching harder than a liberal for dirt on Trump I found nothing.
I then went to my old friend who started this project and he said well it is a GM and they are notorious for bad connectors so we tightened them up with a pick at the PSM and put dielectric grease on the plug going into the trans and BOOM
Problem solved
Been towing great for a week now!
BIG Thanks to Mike L. For helping me see the forest instead of focusing on a tree!
Hope this helps someone in the future :thumb: