I've got a weird one here. My truck will go to redline while not in gear. It will accelerate when not deep in the throttle. When you put your foot in it...it cuts out all together. If it doesn't stall, it takes a second or two to get it back up to powering the truck forward. I can't pull codes casue for some reason the obd outlet stopped working. This started about 100 miles ago and is getting worse. It seems like its not so bad when the engine warms a little, but gets worse when it gets to operating temp. Any ideas. Its an 02. Ive been thinking it's a cam sensor, crank sensor, or map sensor.

 

Update-
Tech articles say there is no crank sensor and I had an extra MAP layin around. I tossed it in and it didn't fix it. I'm left with a Cam sensor problem, and "generally F-ed" as my likely options. I'm shooting in the dark, but its only a $90 crap shoot.

As for the OBD plug, I tested the 7 and 11 pin (communication pins) with a multi-meter and I have a varying voltage, so I know that the computer is transmitting. I still cant get the computer to talk to the scanner. Anyone ever replace the OBD plug before. Any idea where to get a generic?

 

You shoot craps , or do some testing , but you should start with the problem you have , no codes , means that that should be fixed 1st .
Fuel pressure ?

 

Fuel pressure is good <12psi. I plan on rebuilding the OBD plug after work. Like I said I am testing stuff as I go. This all hit at once. The OBD has never been reliable because the entire wire harness out of the donor truck was put into the HMMWV, leaving a huge ball of wires that can not be thinned out.

 

APPS?? try resetting it

 

This doesn't feel like any apps problems I've had before...so no, I didn't reset it. This problem is intermittent and cuts fuel 100%, no fading or stuttering. Maybe the fuel shut-off solenoid? Might that be affected by lots of power running through the VP44? Do both signals run anywhere near eachother.

I checked the OBD plug again with some help from my local Dodge dealership and I don't have power to the 16 pin. That runs back to a block that is supposed to split 12v 5 ways and it's not hot, so I jumped it. Still no result on the scanner. I jumped the 3 and 11 pin (CCD Bus +&-) which resulted in a >.2v varying signal (ie baud signal). The 6 and 14 pins jumped to a ground result in about 4.8v constantly (all keyed). 7 is a transmit so it does nothing. 4 & 5 are grounds and test ok as such. This F-n sucks. If the signals are good, why wouldn't the scanner pick up the truck? Anyone have more information about what the signals and voltages should be?

 

Unhook your TST Powermax-Edge w/controler and see what it does.

 

HAHA!!!! Good call. The truck wont start at all now! I'm guessing its a bad APPS, even though its BRAND SPANKIN NEW (less than 2 months)....unless there could be another gremlin?

Edit- Anyone think it could be a bad computer? As I think about it, the APPS should still be working because the truck still responds properly to throttle sweep with the TST box in, it just won't push under load. It wouldn't start when I fully bypassed the TST harness and hooked the original harness up to factory spec.

 

Fixed it.
Bad fuse in #12 position to power the OBD plug. OBD not communicating with ECM resulted in shut down of system code 1689 & 1688. Shut down of system caused all power control to be routed through TST box resulting in blowout of 5 amp in line fuse. Replaced both fuses, reset PCM codes. Runs like a top. Thanks for the help to those that posted.