Diesel Performance Problem

[tvs2008]

If this is a bit long sorry but I think the whole situation neds to be explained for any help in diagnosing this. The truck in question is a 2004 Kodiak Duramax diesel. The truck runs great until now. Here is the situaution.

I get a flat front tire on this truck and get it towed to my local tire shop about a mile from the breakdown location. The vehicle sits for about 48 hours before both front tires are replaced. The tire shop never started the truck while they had it. When I pick up the truck it is completely dead. It takes about 15 minutes to jump but it eventually does. My shop is right down the street about 500 yards. Everything seems OK at this point.

The next morning the battery is dead again but it jumps in 30 seconds. After the truck warms up the truck is on its way except there is a problem, it won't go over 40mph. Once it hits 42mph it starts to back off and will not accelerate over this speed. After scanning the computer we get a bunch of wheel sensor codes. The truck seems to think it is doing 85 mph when in reality it is doing 40 mph and this in turn is activating the governor so it will not rev too high.

I know it's not in limp mode because I have dealt with that before and I have normal power until 40mph or so. The limp mode is much slower than 40 mph and it seems to bellow smoke from the exhaust when it is in that mode.

Another thing that is happening is the gauges are either not accurate or don't work at all on the dash. Different gauges do different things with each start. I will say that most of the gauges seem to be coming around and functioning better but the speedo is still off by an insane range.

I was told by one person that it may need a stepper motor. The codes all seem to be speed sensor related and they seem to be the sensors on the side of the truck that had the flat tire. Everything was perfect before this flat by the way. Also the ABS light is on. Any suggestions or advice would be appreciated. The nearest diesel chevy repair is about 60 miles from me. Is there a way to bypass this? I tried a couple of things but they didn't bypass. this just seems weird. Thanks for any responses.

[masterp2]

The truck seems to think it is doing 85 mph when in reality it is doing 40 mph and this in turn is activating the governor so it will not rev too

 

is that what the speedo reads also?

 

odd indeed.

[jro909]

shotty speed sensor?

[markw8]

If you havn't already, it would be a good idea to fully charge the batteries. If they are very old have them tested. With known good and fully charged batteries then go back to your other problems. Weak and bad batteries can cause all kinds of trouble.

 

Check the WSS, the harness and the connector. See if it looks clean and tight, no damadged wires.

 

Mark

[brainpause]

If you havn't already, it would be a good idea to fully charge the batteries. If they are very old have them tested. With known good and fully charged batteries then go back to your other problems. Weak and bad batteries can cause all kinds of trouble.

 

Check the WSS, the harness and the connector. See if it looks clean and tight, no damadged wires.

 

Mark

 

+1

 

I was going to suggest unplugging the ground cable and letting it sit for a while.

 

Larry

[Black02Silverado]

If you havn't already, it would be a good idea to fully charge the batteries. If they are very old have them tested. With known good and fully charged batteries then go back to your other problems. Weak and bad batteries can cause all kinds of trouble.

 

Check the WSS, the harness and the connector. See if it looks clean and tight, no damadged wires.

 

Mark

 

+1

 

I was going to suggest unplugging the ground cable and letting it sit for a while.

 

Larry

 

 

 

It would be a good idea to clean up all the grounds connections as well.

[desrtrat]

when the truck was towed, did they remove the rear drive shaft?. when i was towing we came across this when the shaft was not removed. most likely the key was left on when towed, and the ECM picked up the rear wheels turning, but no other input. try disconnecting the battery to let the ECM reset..

 

good luck..

[FargoZ71]

Flat tire/rookie service worker tear the abs/wheel speed sensor out of the hub? That would explain part of the speedo issue and the abs light. Or possibly the wiring harness to the unit was damaged.. just compare sides.