VSS issues?

[derekja]

Hi,

Well things have been pretty good here in 1998 K3500 land! Until today, that is.

I noticed one of my rear tires low, so I refilled it and went to take a shower and came back and it had gone all the way flat! I guess it was time for new tires anyway. So I jacked up the rear end from underneath the middle of the rear differential, and changed out the tire for my spare. No problem. Well, the jack let off a bit fast while I was lowering it, but no real problem.

Then I went to drive and discovered that my speedometer doesn't work! I only drove a few blocks, and never above 30 or so, so I don't know if the shifting was doing anything weird. It didn't feel like it.

In carcode, I don't see any relevant codes (security code that I cleared from when I last jump started the truck, and some random misfire codes during warm up, but nothing VSS related.)

I know very little about carcode, though, and might just not be looking in the right place.

Well, for that matter I know very little about the VSS either. My only guess is that the jolt from the jack letting the back end down quickly dislodged a wire or something? I hope so!

But where to start looking? Any thoughts are much appreciated. I'm going to start digging into this more in the morning.

Thanks!

--Derek

[derekja]

loose connection behind the glove box, it seems. They all felt ok, but after poking around in there everything suddenly worked again. For how long, I wonder?!

Thanks.

--Derek

[a5150nut]

On mine it is just left of the glove box opening. White plastic case about the size of a cigarette pack. There was a thread about how to rework one with the jumper settings to change for different tire sizes. I have 285's with 4:10s and mine is set for 3.73s and is dead on.

The manual has a hard to follow check sequence. You'll kneed an ohm meter and lots of patience. If you think it's a short or loose connection I would use some tuner cleaner. All it takes is someone to have touched the edge card connection and the acid in the body oil will eventually cause electrical problems.