Accelerator Pedal wiring/ engine brake

March 24, 2013, 03:45:38 am

Well, I thought I had cracked the engine brake issue I reported on with the replacement of a relay. That turned out to be a fluke it was not the fix the engine brake failed after 38 miles.
I had a dual fix, sort of, when I replaced the relay; I had also been grubbing around under the dash and had seen that the harness to the accelerator pedal was taut at full forward pedal slide extension. (Towards the driver) I tried to correct that and also checked the plug and wires for any problems.
So the coach went in for its annual service and the engine brake was fine. The mechanic took her to the local government test station (over here in the UK after a vehicle is 3 years old it has an annual test) and did 20 miles each way without an issue on the engine brake.
I collected her and was nearly home and the engine brake stopped working!!!!!!

I drove straight back to the garage
They looked at the accelerator connections and declared them OK. Various other checks revealed a Cummins service bulletin on Engine Brake wiring in the rocker box. A replacement harness and special clips were available for a solution to possible chaffing causing an intermittent fault. Well we all thought that was it.
I picked her up yesterday and once again was nearly home, and sitting at some lights, thought that the pedal slide was too close so moved it to suit me. Turned down the hill and the engine brake was not working!!! I stopped and fiddled with the plug and wires to the accelerator. The engine brake returned!! So it must be in this plug/wiring.
What I find difficult is that I have no issues with the throttle itself so which of the 6 wires has an effect on the engine brake?

Anyone have any thoughts or help here?

Michael

2008 Allure 31683, Cummins ISL 425

Re: Accelerator Pedal wiring/ engine brake

Reply #1 – April 12, 2013, 04:50:37 am

Yahoo Message Number: 87075

Engine Brake and Throttle sensor

For those who responded to my various posts I am pleased to report a finite solution.... I hope says he tempting fate!
After replacing, Hi off Lo switch, relay, removing brakeswitch.com box, replacing some battery connections, harness inside rocker box for brake control, I finally homed in on the throttle sensor at the accelerator pedal. Lucky breaks pointed me at it or the harness. After much thought and feedback from the sensor manufacturer I replaced the sensor and had a harness on standby. A 40 mile test proved positive but I still really wanted a 100 mile plus trip without issue. BUT, I built a good rapport with the UK distributor of these sensors and he agreed to put the old unit to a severe test. Well he telephoned this morning, the sensor was shot! The idle switch was failing or failed and there were other symptoms developing like a flat spot in the acceleration curve. So it was about to totally die! I feel more confident with my opening gambit... maybe?

Michael

2008 Allure 31683 ISL 425

Re: Accelerator Pedal wiring/ engine brake

Reply #2 – April 12, 2013, 04:33:50 pm

Yahoo Message Number: 87082

Good job Michael and thanks for letting us know the solution.

George in Birmingham
'03 Magna 6298

Country Coach Owners Forum Country Coach Motorcoach Forum