Hey all, I've recently purchased a 2000 f650 with the 5.9 24 valve with a 6 speed manual. I just overhauled the top end, new injectors , new turbo, air cooler, alternator lube and filters 7000 miles ago.

Truck has been running great until last night.

Got a check engine light popping on and off, was about 150 miles from my destination, then it stayed on constant, no over heat, plenty of fuel, and voltage, but I noticed every time the engine light came on oil pressure forage would drop like a rock to zero, eventually the truck wouldn't accelerate past 55. I would ease off throttle, light would go out, acceleration returned but at 55 the light would come back on, acceleration would cease, and oil pressure would drop to zero then even out.

Honestly I don't really know it the ammeter was dropping off before or if the issues are related.

My obd2 port wont pick up my scantool, no scan tool I've plugged in has been able to connect with the truck since I bought it.

A bit long winded but I figure plenty of info might get results, where should I be looking??

 

Oil pressure sensor. Now this is a wag, but I had a 2000 Freightliner MT55 at work with that same engine that had a bad sensor and I got shut down/restarted/shutdown repeatedly.

I would also make sure you don't have an oil pressure problem--a mechanical gauge at the engine will help there.

 

The OBD2 port does nothing in these trucks. You need the proper scan tool for the 9 pin round Cummins port.

 

AH HAH!! I did not know of this plug? Where would I find it on the truck and do you have a link for the scan tool?

 

I've guaged the oil pressure, no issues there, checking tps now,

 

The 9 pin is located towards the left drivers kick panel. You may try the 9 to 16 pin adapter but its limited in function. I use the Cummins Inline-7 adapter and software. It's not worth the purchase if you only have a single truck. Easier to visit a Cummins dealer for codes.

 

Thanks for that info !!

I have no idea what happened but the symptoms I was having the other night are gone, and all I did was run some tests. I'm thinking that maybe the plug at the tps was a bit loose. The pressure clip was broken and the plug slipped right out. It tested good but after I plugged it back the check light was gone. .....the little things...