Kenworth t800, no bump idle

[joed2323]

Already tried the clock spring since we had one, and swapped out the smart wheel master control module with no luck. Also tried the cecu from another unit.

The jakes work on the smart wheel...

But no bump idle. Any ideas where else to look?

I made sure the clutch pedal is fully up to the top, as well as brake pedal.

[stevesparts]

you did try another ecm? ,Take a look at the settings in the ecm. might not be set right in there.
mine did something like that found that some of the settings where wrong and had to turn them on/set right.
it showed on insite that the brake was on, so no cruse or idle up.

[joed2323]

I only tried swapping out the cecu under the cupholders. They had diff numbers on them but I think that doesnt matter??

I do know I tried watching the switches on insite ang their is no difference at all for cruise when I activate it or deactivate it, insite shows no change like its not responding.

But when I try the Jake settings, 1,2,3 the status does not change at all on insite like its noy responding but the jakes do in fact work and always did, just not the bump idle.

[joed2323]

Can the no bump idle be a ecm issue? Very weird how the jakes work, horn works everything on thr smart wheel but the bump idle.. I do not like bringing any truck to the dealer but im debating on it.

If it was the clutch switch the jakes wouldn't work.

Ive asked a few people, and the things they suggested I should try well, I already tried.

This truck is technically down since the drivers can not bump the idle up to run the pto at a higher rpm to load and unload crude oil

[kryten]

Did it work before? I know with my Volvo it is an ECM setting to both enable/disable the high idle and also what the max RPM will be. I think I had the shop set the max RPM on mine at 1000 and when I bump the switch there is a 50 rpm change.

[schISM]

I had a T800 with an N-14 that had the same problem. I discovered by accident that the switch in the dash didn't have a proper ground. Ran a jumper from the cigarette lighter ground and voila! it worked.

[Rawze]

(07-20-2016 )joed2323 Wrote:  Can the no bump idle be a ecm issue? Very weird how the jakes work, horn works everything on thr smart wheel but the bump idle.. I do not like bringing any truck to the dealer but im debating on it.

If it was the clutch switch the jakes wouldn't work.

Ive asked a few people, and the things they suggested I should try well, I already tried.

This truck is technically down since the drivers can not bump the idle up to run the pto at a higher rpm to load and unload crude oil

Has anyone checked in Insite to see if the feature is turned on?

[joed2323]

Yes this has recently worked before, we use this everyday to engage the pto theb raise the idle up to 11-1200rpm

What switch are you refering to in the dash?

[Rawze]

(07-21-2016 )joed2323 Wrote:  Yes this has recently worked before, we use this everyday to engage the pto theb raise the idle up to 11-1200rpm

My prostar did something similar once. PTO and a couple other things only on the steering column stopped working. Truck had no other symptoms, no alarms, nothing. I swore it was in the wiring or clock spring, etc. -- chased it and tested out wiring/buttons, etc. all day to no avail. The truck ran great otherwise with no other symptoms. No matter what I tried, the buttons for the PTO on the steering wheel just refused to work.

Several hours later (more like all day) it turns out that the cab controller thought the keyswitch in the dash was in the "cranking position" non-stop due to fuse that had tarnish on its contacts due to age. Took forever to find.