2001 KW C15 loss of power & the speedo is bouncing around.

[Bobby]

Last load of the day ( dump truck ) pulling a pretty good hill I lost power suddenly and the check engine light came on. I checked the gauges and everything was good. I pulled over and was thinking fuel filters because it felt like a loss of fuel, but it came on very quickly...i.e. I was pulling the hill with good power then it just died off..but kept running. The filters were changed 7k miles ago.

I shut the engine down and checked under the hood and everything looked good. Start her back up and she had good power again and the check engine light was off...so I dump the load and head for home...35 miles. She ran pretty good except for a couple of times she wanted to loose power again and the speedo was bouncing around but all other gauges seemed fine.

The other thing was they had a wash rack to wash dirt and mud off the tires as we leave the dump so water was flooding the sides of the wheels, but it did'nt look like any water was getting on the engine and it was about an hour since I passed thru the wash rack when the power loss happened.

While I think I may have a fuel filter problem ? and i'll change them out first thing... I kinda think this might be electrical ??

I checked the battery terminals and everything looked good. The truck does have battery shut off's. The Amp's and volt gauges were normal too.

any Help ! or idea's appreciated

2001 KW C15 W 227K miles

[Kranky]

She ran pretty good except for a couple of times she wanted to loose power again and the speedo was bouncing around but all other gauges seemed fine.

Something's going on with the vehicle speed sensor (located at the transmission output shaft) or the wiring in the vehicle speed sensor circuit.

That's why the speedo was bouncing around.

When the ECM does not receive a signal from the vss, it will not let the engine run at full power, sort of a "wake up call" that you need to get it repaired.

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[Bobby]

I'll bet it got moisture from the tire wash.

So it's located at the rear output shaft of the transmission ?

Kinda like were an old speedo cable would hook up ?

[boneebone]

I doubt is from the tire wash, Spend the money and replace it. it is about $35 dollars. From the symptoms you are explaining, it is ready to go six feet under.

[TK THE TRUCKER]

Also check the wiring to your accelerator peddle. I've had trouble with this causing the engine to go from idle to full throttle just by wiggling the wire. It gets dirt, water and other stuff down there and corrodes and such. We needed to get a new plug for the wiring harness that plugs into the peddle but Kenworth wouldn't sell just the plug, they would only sell the entire pedal assembly for $600. We were able to flip through a GM parts book and come to find out the same plug was used in a 86' Oldsmobile or something like that. Ordered it from our local dealer for $25 bucks and problem solved. I was glad to because you would just be cruising along and all of a sudden it would just go to idle or go full throttle or bounce back and forth between the two and really do a number on the drive train. It also caused the engine lights to come on too. 8) 8)

[marylandkw]

I gotta agree with spitshifter.

I had the exact same thing happen in a dump right after a tire wash. IIRC it's about a 20 dollar part and easy to replace.

[marylandkw]

Doh' double post

[Bobby]

Well, I fixed it the other day.

I ran it up ( New speed sensor ) against a piece of paper then backed it off a good half a turn or so.
Seems to be fine.

Thanks for all the help and info... I know it saved me alot of grief.

Splitshifter...Thanks