Peterbuilt 379 wiring issue

[pbateman]

hey fellow dk members.Looking for some help here. Had a 379 Pete that had a ECM replaced and the complete dash harness replaced and found a few issues with the wiring where some things weren't working properly. The only issue I have left is I can get the engine idle to work properly nor the cruise control to work. Anyone with any suggestions would be greatly appreciated.:banghead: Vin # on the unit is n689746 or if u need an ESN I can provide it also.

[djz4248]

check ecm service brake signal circuit. needs closed contacts to enable. cruise must be enabled in ecm also. have found problems with from upper left harness on cowl down wher it goes under cab and loops around over by starter. insite would be a great help to see switch status.

[pbateman]

thanks djz4248 have some where to start looking the dash harness had all kinds of cut wires in the dash and this is why i replaced it. It would be nice if insite would go a little more in depth with the switches and wiring diagrams on the trucks.

[pbateman]

Hey djz did what you said and didn't come up with anything. I think I have a check Sum error in the ECM is there a possibilty that this may be an issue ?

[pbateman]

Hey fellow Dk members. Got an issue with a 379, 06 ,m11 vin#N689744 I have no cruise or jake brake and the clutch switch is good and just to be sure of it I installed a new one just incase.Its a brand new harness out of the firewall so I have no issues there is there a posibility an issue with the programming in the ECM??? Need help on this if anyone has ever experienced this the driver is driveing me nuts because of no jake and no cruise! Thanks in advance!!!!!:giveup:

[RSwire]

No cruise, no Jake? Did you check your TPS, it should have an idle validation switch( tells the ecm throttle pedal is at rest), I had this go bad ia a few other vehicles.

[djz4248]

check with insite. verify clutch switch, should show released with pedal at rest and depressed with pedal pushed. idle validation will show on-idle with pedal at rest and off-idle with accelerator pushed slightly. verify cruise and engine brake options are set properly in settings. does fast idle or pto work? sounds to me like a clutch circuit wireing problem.

[pbateman]

Thanks for the post and help will check these out on Monday! just got done dealing with a wiring issue on a freightliner. Good grief the drivers need to stick to the driving and leave the mechanic work to the mechanics!!!!!!!:thrasher:

[pbateman]

Got jake brake going but no cruise yet have checked all setting and everything is good with the exception of brake pedal is shows in a depressed state but when youpress on it it will not do anything is there a possibility this could be messing with the cruise??? Thanks for any help in advance!

[djz4248]

yes that is probably the problem. not sure where switch is on 06 but would on floor ahead of pedals. switch needs continuity for ecm to see brake released. open will show pedal depressed.

[pbateman]

Thanks DJZ that was the issue and the location of the switch is directly under the steering column just for furture reference for anyone who may check this forum out. Appericate all the help once again.

[pbateman]

Hey Dk friends been a bit been out of town and just got back a day ago. Wanted to say thanks again to DJZ and RS for the input on the jake and cruise issue I had on this truck. Had to replace both brake switches cured the problem so thanks again hope everyone stays cool with tis heat!!!!:shakehands: