Hello. First post in here and first Cummins. Maybe you know the answer to this unique issue I have on my 2005 Dodge Ram 5.9 Cummins automatic w/overdrive transmission? 196,000 miles.

It's the original transmission and motor. All fluids/oils and filters regularly changed and kept clean/new. Not used to tow often...4-5 times a year at most and 8,000 lb loads at most.

I've asked 4 tranny shops and a few forums and Facebook groups but no luck finding same problem or proper fix. I'm wondering if I'm just that special?!?? Lol

One mild Fall day last year I had driven 260 miles on interstate at about 75-80 mph. It began slowly reducing speed over 6 miles from 80 to 15mph. Moving fuel pedal would not do anything but make it stumble a little a couple dozen RPMs up or down. Stopping and restarting it immediately did not help nor did changing gears manually.

All fluids were fine, not too hot and no burning of anything fluid or conduit wire was observed. All looked good under and above it.

I stopped it for 30 minutes as I checked it over. It would drive normally after that, but it would only go 25-30 miles before it would slowly slow down again as described above. I did this over many cycles all the way home 260 miles. I'd turn it off and on again, completely off as it rested for 25 minutes. The batteries seemed to be getting charged (started well each time) and no warning lights were on. Once or twice, when I drove it until it would not even crawl anymore (1-2 mph, I was testing it), it stalled. So it wasn't hard starting or hard-stalling unless I took it all the way down to 1-2 mph speed. It was not idling weird either.

Could this be an electrical ground failure or electronic issue? If I had a battery connection loose or anything disrupting the flow could it cause this? It seems like something is getting tired and needing to cool down or something but nothing was overly hot or smoking. What's weird to me is it's not slipping in the usual way of revving up but not moving. It would usually get no lower than idle.

Tranny shops haven't heard of this before. No transmission codes either. They want to charge me $3,000+ for new or rebuilt tranny. I want to rule out wiring and electronics (that don't throw codes) first.

Any suggestions? Heard of this ever before for an automatic transmission?

I've driven it around town since then and it did repeat the same behavior after 25-30 miles of use, and this was at lower speeds under 45-50 mph.

 

try changing governor pressure solenoid, and transducer, can buy both on Amazon, they are located inside tranny pan. do a search and you will see how to do it, cheapest way to start.

 

Are you sure it is transmission related?
From your description it sounds like the engine isn't producing enough power to go faster. Any chance the fuel cap isn't venting (drawing a vacuum on the fuel tank), and starving it for fuel?

 

I'm afraid the sky is the limit on these rigs. Not like the 1970s anymore unfortunately lol
is the cap supposed to keep vacuum or be free flowing?
It's the cap that came with it new I think.

It may be tranny or 3 other majors, or a tiny little error. Ah the beauty of troubleshooting these things lol

 

Yeah that's been done. With tranny fluid, filter and bands adjusted too. Shop said bands were maxed out...as in no more adjustment left.

 

Not sure on that specific year, (could have some other form of a vent on the fuel tank), but it's easy to check.
Next time it happens just hop out of the truck, crack loose the fuel cap and see if it make a huge whoosh sound as it sucks in air. If the issue resolves itself immediately after loosening the fuel cap, it would be a good place to start looking.

You said no transmission faults, were there any other faults in the system?

 

Did it stumble??

Sounds like a lift pump to me.

Chay