Engine/Transmission (1998.5 - 2002) engine revs up when hiting bumps

[GreggNoble]

when in high gear on the highway my cummins will rev up sometimes 500 rpms instantly when i hit a bump in the road, our roads here in Newfoundland Canada are full off bumps created by frost in winter. is this my torque? is my transmssion shot. someone said that it might be the brake light switch but i ruled that out. any thoughts? thaks

 

[blacksheepdiesel]

Is this with cruise on or off? If it only happens when the cruise is off it is simply the touchy throttle being moved ever so slightly by your foot. If it happens with cruise off and cruise on then my guess would be transmission or torque converter if it is an auto, clutch if it is a manual.

Godspeed,
Trent

 

[Gene Heck]

I know you said you ruled out the brake switch but that is the most likely problem. Check it again. If it's at the edge of adjustment and the brake pedal bounces a little when you hit a rough spot it will send a "false" signal to the PCM that the brakes are being applied and the TC will momentarily unlock. Adjust the brake light switch or if your roads are really that bad you might have to add a helper spring to help hold the brake pedal back against the switch.



Gene

 

[GreggNoble]

thanks guys, this happens with cruise off,and my truck is Auto . i rearely use cruise. in a previous tread someone told me to check the brake switch so i use to hit the bumps with my left foot under the brake pedal lifting pressure on it so that the bump copuldn`t move it and the engine still revs up ,so i guess its something else huh. doesn`t seem to be a common problem there isn`t much to be found in the search option.

 

[blacksheepdiesel]

Has it always done this?

Try using the cruise and see if it still happens.

Godspeed,
Trent

 

[GreggNoble]

no it just started it about a month ago,and doesn`t seem to be getting worst, i try to slow down on bumps but there is one every 100ft up here ha ha ha ha could the slipping be causing damage?