Help with my speedo and odometer, 2001 GMC Savana.

First the problem,  my speedometer, odometer and PRND321 display not functioning.  Analog speedo, digital odo and prindle display.

Typical problem with the Vehicle Speed Sensor will take out the odo, but also caused shifting problems, it shifts fine.

The other common problem is a Body control Module,  this model doesn't have one of those.

I have taken the gauge cluster to have it tested and all is well with that.  Last night I unplugged the two main modules under the hood just to see if there was any corrosion.  Then cycled the shifter while trying to start it verifying neutral safety switch operation.

To add insult to injury, this happened the day after I sold it, but it is not gone yet.  The sucker who bought it (GRM Member) did not pick it up yet so I am scrambling to get it fixed.

For now I have my GPS placed on the dash, it shows speed, mileage and can tell me how to get places.

Looking for some trouble shooting options that don't involve throwing parts at it.  There is little to no info on my web searches that are of any use.

I may throw a VSS at it anyway as they are relatively cheap but I have almost no confidence that it will change anything.

I verified with my scanner that the speed sensor is working.  With the van on a lift and tires spinning I can see the speed go up and down so I know that the ECM is getting a signal and regurgitating it. 

Also verified is that the three ground wires and two 12v wires have a proper signal.  All ground wires to ground have continuity and all combinations of ground to 12v give me 12v output.

Where can I find an Instrument Panel Cluster pinout?  34 pin in two rows, it does not match a corvette, pontiac or anything else that I have found.

On a side note these vans have auxiliary circuits for upfitters since most are used for commercial purposes.

I bet its in the cluster.  If you have a VSS signal at the ecu, that info "should be" transmitted over the data line with all the other gauge info, I think.  That is how its done in the 05 Savanna donor van I used for my 67 Camaro.  It is also possible that info is washed through the ABS computer, but I don't think so.

My first step was to have the cluster checked.  He plugged it in and everything worked, he told me the mileage and swept the speedo.

I really need to find out which wires go to them and what their outputs should be.

My next step is to pull all of the wires out of the IPC harness and verify that the connections are tight where the pin slides in.  There are lots of them so I was hoping to just check the ones that are not working but can't find any info on them.

Fixed at the dealer, they had it done and ready to pick up before I was able to tell them what I had done so far.  It was a shorted wire under the carpet that was sucking down the power supply to the dash.  I never would have found that.

The mighty van is off to another GRM member as an expedition vehicle. 

In my search for my dash problem I found that these vans come with extra 50 amp circuits built in for upfitters to use.

This is how you change plugs in a chevy van.  Remove front wheel, lift up the splash guard, all eight are right in front of you.  The lift helps some, but I have done this in the driveway without removing the wheels.

I'm still jealous of the lucky SOB who bought this. If they change their minds I call dibs. I was too late 

In reply to Erich :

Strangely enough his name is Eric, at one point I got the two of you mixed up.