Runaway Cummins (almost)

2001 Dodge, 4 X 4, Cummins Diesel. I stopped at a rest area after being on the road for about 60 miles on my way to a car show, towing my car. When I placed the shift lever of my truck in "Park", the engine RPM started surging several times up and down from idle to almost 3,000 RPMs to the point where I had to turn the ignition off to avoid the engine over-revving. After sitting for several minutes, kind of in shock, I checked for "error codes" and two codes were displayed: P0122 (APPS Sensor) and P1398 (ECM companion code). Also, the check engine light was illuminated. I was able to make it back home with no further issues. The truck ran fine, the check engine light went out, but it is still throwing the two error codes (even after I cleared them by disconnecting the battery for several hours).

I replaced the APPS sensor 1 year and 1,300 miles ago after I was experiencing an erratic idle and getting a P 1022 code. I purchased an Alliant Power APPS sensor and it is hard for me to believe it has gone bad after such short use but apparently it has.

I plan to make an appointment at the Dodge Dealer to have a complete scan of my electrical system just to be sure the P 1022 code it the only problem. Has anyone ever heard or had this happen with their 5.9 Cummins?

My 93 Cummins ramp truck did the runaway thing a couple of times, I couldn't shut it off with the key! I had to open the hood and take the hose off the turbo then put a phone book over the turbo tightly until the engine died. I still have no idea why it did it but it happened again a month or so later. Good thing I had an old phone book in the cab...

Had an 89 with 727 that would do that in neuatral or park but not in gear.Up and down. Not like a Detroit, but there was no stopping it unless you turned it off or dropped it in gear. Rebuilt HP pump cured it.

Ended up taking truck to dealer and had them do a complete "scan" of the PCM & ECM. Came back with faulty APS/TPS code P 0122. Due to the age of the truck, Chrysler no longer stocks the APS. I replaced the Alliant Power APS (which I had installed 1 year earlier) with an OE Cummins APS. So far, so good.

Overspeeding a big diesel can be catastrophic, and humorous in a macabre kind of way. I have an account that builds high wheel AG-sprayers with hydrostatic wheel motors to propel the vehicle at road speeds nearing 40mph. These are the AG sprayers on near eight foot tall tires. I was back in R&D one visit and they had a Cummins 500hp diesel on the shop floor, that had suffered an overspeed event. They were testing new wheel motors, but on the road test, decel down a long grade, the momentum of the vehicle was actually causing the wheel motors to act as pumps, which drove the main hydro pumps, which spun the diesel, to well over 3,000 rpm, and......BANG!

Head was off the engine and I looked in the bores and started laughing. One piston, what remained of it, was jammed, sideways in one bore. In another bore the piston was, well, gone, and the remains of the con-rod small end had whipped around in the cylinder. The oil pan was full of schrapnel.