[ARBrad]

Having a weird issue with my recently purchased 2003 F-350 with the 7.3.

When I start the truck, the engine runs fine, it'll shift and brake fine. But there will be no throttle response and no gauges. The only way for me to get it to kick back to life is to reach under the dash and gently pull down on the wiring harness going up into the cluster. Then it'll work fine. It happens more often when the truck is cold, maybe because the cables constrict? When I let it warm up a little first it either will work fine or will come to life faster/with less wiggling.

I understand that the overdrive button chafing on the shifter can cause these same symptoms, but I'm not blowing any fuses, the OD button works fine, and the problem seems to be farther "down stream" in the electrical system.

Normally I'd take it in to a dealer, but they're booked out for at least 6 weeks, and I need the truck to get around. So I'm going to try and correct this issue myself. Tomorrow is going to be a "monkey around with wires and see which one makes the connection" day.

If anyone has any knowledge on this topic that could be potentially useful with this situation I'd love to hear it. Maybe the specific connector I should be looking at? Or a wiring diagram of some form? Any help would be appreciated.

 

[ArcticDriver]

I am surprised that you are not blowing a fuse.

 

[ARBrad]

I am surprised that you are not blowing a fuse.

Me too. Especially since it's actually cut out while the truck was running and driving.

 

[ford_doctor]

All are provided power by fuse F2-45 on circuit 640, a red wire with a yellow tracer. Since it seems like an intermittent open circuit, diagnosing might be done by disconnecting the AP sensor and measuring the voltage at pin #6 of the connector (RD/YE) and monitor the voltage on a multimeter while moving, bending and twisting the harness to locate the open. THAT is how I might approach this. When looking at the electrical schematic I do not see any connectors between the fuse panel and each component on the circuit but there is a splice... which can go bad. Keep in mind that a wire chafe causing a short to ground does not always result in a blown fuse if it is a poor path to ground and only pulls the voltage in the circuit down but not totally shorts.

 

[ARBrad]

I ended up taking it to a shop where they took the dash apart, removed the cluster, and checked the wiring harness. They said everything looked fine, suggested it could be the PCM. I didn't end up having them replace it, they just reassembled everything and I went on my way. It's been about a month now, and I haven't had an issue since. Even when temps are in the negatives the gauges and pedal work without fail. Maybe it was just a loose connection? Who knows. Just happy it's fixed. Thanks for the input folks!