Coming home after a trip to Little Rock for the birth of a new, healthy, granddaughter, my speedometer started jumping up when I was running speeds between 30 and 40 mph and my ABS light would flash. No code for VSS but I did have a P0603, P0488 (always) and P0341 (not related I don't think). Truck starts and runs fine. Battery connections are clean (done recently), and it hasn't been long since I cleaned the VSS sensor when I changed the diff oil. It happens so fast that you can barely see the ABS light flash.

 

Congrats Grandpa!

 

Congratulation Tim. Just wait till she hits the teen years. I'm going thru that now. LOL.

 

Congrats Tim. Have you checked your alternator connections.?

 

My 05 would do that, the speedo had a mind of it's own every now and then. I knew I was only going 30-40, but the speedo would indicate 70+ for a few seconds, then fall off and quit, then jump back and show 50, then 20. Bounce, flutter and act all ADHD.

After a couple miles or shutting off and restarting the speedo was fine.

The odometer wasn't effected and I had no CEL or any other indication something was whack. At the time (late 2007?) the dealer informed me the cluster would be replaced per the TSB only if it occurred permanently and not erratically. Coincidentally not long after that it behaved itself.

Josh

 

Mine jumped to 100 one time almost like the PCM did a reset but the ABS light is flickering every time it happens. I haven't driven it today because I'm replacing my fuel pump motor and doing some other stuff. I checked the connection at the diff for a leaking sensor but it looks dusty dry. I may just throw a VSS in it since it's so cheap just to see if it makes a difference.

 

Pretty sure it's an issue with the dash cluster and has nothing to do with the sensor.

Josh

 

Here are the TSBs the effected my 2005...

06-7-4***STUCK OR JUMPING / BOUNCING / ERRATIC SPEEDOMETER AND/OR TACHOMETER
07-11-2*** STUCK OR JUMPING / BOUNCING / ERRATIC SPEEDOMETER AND/OR TACHOMETER

Josh

 

I couldn't reproduce it this afternoon after I got done with my fuel pump (which is incredibly quiet now). I suspect it will rear it's ugly head when it gets cold again, so I should be good for a few more months.

 

Tim,
Try monitoring the sg2 for mph to see if it also shows the jumping speed.. that should help isolate to abs sensor or wire vs dashism.

Sent from my Sprint PC36100 using IB AutoGroup

 

Happens too fast to catch it on the SGII although I've looked. I can't get it to repeat what it was doing

Mine is an 04 so I'm not sure they apply as I think there are differences in the electronics of the dash, but I'll certainly use the information to try and diagnose it. My first thought was VSS because the ABS and VSS are on the same pin in the PCM connection to the cluster.

I did check the alternator and all battery connections as I had them loose a couple of weeks ago, but they're clean and tight.

 

VSS or OSS?

 

VSS. I don't know what OSS is but guessing it's some kind of speed sensor.

 

Output Speed Sensor

Josh

 

congrats!!!
of topic--I grew up in Little Rock--kinda wish I still lived in the area.