P1391 - 2002 Dodge Ram 4.7 with screwy wiring

[jerms]

Howdy, I own a stereo install business in Texas (also have 20 years mechanic experience).
One of my customers brought in a 2002 Dodge Ram 1500 4.7 Liter with some crazy wiring.
I got the stereo sorted and wired but a few days later his truck threw a 1391 code and won't pass inspection - he's convinced I caused this and has left the truck with me to fix it or he'll slap a lawsuit on me. I figured I'd give it a shot since I've got the experience plus my lawyer costs $350 an hour.

Initial Symptoms:
Throwing 1391 code
Running rough at idle
vehicle dies at take-off with air conditioner on

Things I've done:
installed new cam position sensor (old one seemed okay but I've always been told to replace cam and crank sensors at the same time)
installed new crank position sensor (old one was bad - checked ohms)
Checked timing marks - line up fine
pulled throttle body, iacv, tps, and mass airflow - cleaned everything, checked ohms, fuses, and relays - everything checks out, throttle body was caked with crap, iacv was pretty bad
Reset computer
Disconnected battery and reconnected

Symptoms now:
Truck runs perfect
No dying, steady rpms under load
vehicle STILL THROWING 1391 CODE

Ideas, comments, questions? don't care about business advice regarding how I'm taking care of it - just want the customer happy so I can keep my A+ BBB rating.

 

[RonJon '06]

IMO all Dodges have screwy wiring.

To me it seems like you fixed the problem by replacing the bad crank sensor. Maybe try a hard reset by disconnecting the battery and touching the cables together to completely discharge the system. Maybe interference from a circuit running parallel or that is too close to a fuse or sensor?

 

[jerms]

IMO all Dodges have screwy wiring.

To me it seems like you fixed the problem by replacing the bad crank sensor. Maybe try a hard reset by disconnecting the battery and touching the cables together to completely discharge the system. Maybe interference from a circuit running parallel or that is too close to a fuse or sensor?

Yeah, I didn't have to do a hard reset - the ignition switch was bad and the blower motor drained the battery overnight. It reset everything and isn't throwing the code anymore.

I'm going to run it through a full cycle to see if it pops back up.
Most cars have like a 35 mile cycle but I've heard dodges are 80 miles.
Looks like I'm making the Fort Worth to Austin run with the blower motor disconnected in case it's something to do with an inconsistent load on the system.