Still finishing up the details of swapping the Cummins into my 1996 E-SuperDuty bus. I hooked up my cruise control cable to the throttle pedal. Now when I engage the cruise, it catches and then slowly loses speed. Also, it will not respond to any "Accel" switch commands. Anyone have any guess what may be wrong? It all worked fine on the 460 engine.

 

Slowly losing the set speed sounds like a VSS not sending a signal the speed control servo can or will read----did anything in the drive line change?

I do know the wiring from the steering wheel controls to the speed control servo is very specific so if anything in that circuit has changed could be affecting proper operation.

And it could be the servo itself has failed, not related to the swap at all.

Hope its nothing too serious----use your EVTM to double check the affected wiring.

 

I still haven't figured this one out. I replaced the speed sensor in the rear end just to see if that was the problem, but no change. I made no changes in the speed control wiring. Still trying to figure out if the speed control system is dependent on the engine PCM.

 

Since you've not changed anything other than the engine, not messed with wiring or circuits to the VSC servo its entirely possible the PCM affects the VSS's signal to that servo.

Does the EVTM show a direct path from the VSS to the servo? Does it show a path through the instrument cluster by chance? I don't have those schematics, only going back as far as '97 which might be different enough to not be helpful.

Hope you get this worked out---hate to see one tiny detail affect this otherwise cool transformation you've done.

 

This turned out to be an easy fix. To use the 5R110 transmission, I had to use an accel. pedal from a 2006 van with the APPS sensor on it. I made and welded on an arm to move the stock 1996 cable to work the throttle on the Cummins engine. I ended up with a lot of return spring pressure, so I removed a couple of springs at the injector pump and at the cable pivot. The speed control did not have enough power to overcome the spring pressure until I removed about 50% of what I had. Now everything works fine!

 

Wow---have been busy elsewhere the past few days and for some reason while on a return trip 130 miles one way thoughts of your VSC popped into my mind. Was wondering if you'd resolved this yet..........and it seems you did!

Should be about done with the Cobra hauler about now right---or more to do yet?

 

Pretty well finished and very happy with the results. Have about 1,500-2,000 miles on the swap and it's getting a solid 13mpg. (Much better than 7-7.5mpg) Still need to do a little more soundproofing and maybe I'll paint it this year.