Wondering if anyone has suggestions on how to narrow this problem down? I have a 2002 F350 Super Duty 4WD with AT. Friday nite wife was pulling a horse trailer over a steep bridge and pressed the Overdrive button to disengage. The truck dash went dark, all insturments went dead, overhead message center went off, headlights went off (selector was in the auto mode for night), engne kept running and went to idle, accelerator pedal un-responsive. Radio worked fine

The engine idle was normal, smooth. When I got there I turned the truck off and restarted it fine. There were no indicators on the dash, i.e. nothing- no WTS, no bulb check, etc. I turned the headlight switch to normal on and the lights came on. I checked the PCM relay by touching it while turning the key on and it clicked. I swapped it with one of the others (starter relay I think) and no change. I towed the rig home. On level ground you can put the transmission in drive and the truck will move forward like normal with the foot off the accelerator. I checked on the fuses that seemed remotely related and none were blown. I haven't checked all of them.

I'm thinking its the PCM. I have a service manual for my two other 1999 trucks but the 2002 is different enough that the manual isn't helpful (fuse numbers are all different for one thing).

Any tips would be appreciated as I need to get this thing back on the road for horse events.

 

The first thing to do is scan for codes from the OBD II. The scan will give (p) codes, they can be cross referrenced for diagnosis.

From what you are saying though it sounds like the CPS(cam positioning sensor), the batteries are not supplying enough voltage or the Alternator went out on you. I would check things out in that order.

Good luck! Let us know what you find.


Diane

 

For starters you can download a 2002 owners manual. CLICK HERE.

There should be a fuse for the IVS (Idle Validation Switch). See if there is anything in common with that and no power to some of these other things. If the PCM sees no IVS signal it will not respond to TPS (Throttle Position Sensor) signals.

Edit : Nice post Diane. While I was scratching my head you were posting.

Second Edit : I just dowwnloaded a 2002 manual and unlike my 99 I couldn't find an individual fuse for the IVS. I am off base there.

 

Subscribing............. Please let us know what you find out. and good luck.

 

I'm with you Mark. Whenever I see a problem like this I think of what may be in store for me. But I'm not a pessimist, just a realist. I don't think the glass is half full or half empty, but just to big.

 

Update - Problem Solved. The culprit was fuse #45 Ignition switch Run/Start feed which was blown.

It took me awhile to get there since I thought I had checked all of the fuses that I thought could be remotely related. I took the advice from you all about voltage problem as it struck a cord. I remembered towing the vehicle in that night and thinking that the headlights seemed a bit dimmer than normal and the truck had been running the whole time. After the posting yesterday I got my digital battery tester and checked the battery bank which read 12.2 V. I started the truck and the voltage dropped to 11.8 while the truck was running. There obviously wasn't an alternator contribution. I put the batteries on a charger and ran the alternator to NAPA before they closed and had them check it, it was fine.

I have the AE analyzer tool so I hooked it up and it connected as normal and retrieved codes, I could read data points like vehicle power voltage (12.2 V), accelerator pedal position (which show changes when the pedal was pushed), etc. There were some codes but nothing that wouldn't show up when running the truck with a major issue. I recorded the codes then cleared them, shut the truck off, restarted it and checked codes. There were a couple related to battery voltage low and a couple related to air bag warning indicator.

I started looking at the other things that I thought were also wrong. The message center turned out not to be dead it had just gone off. When I pressed the button it came right back to life. So the things that were clearly wrong were, the alternator contribution, the instrument cluster and the accelerator pedal. The instrument cluster and all indicators not responding when the key was switched to the on position seemed to be the critical clue. So I pulled a shop stool up next to the drivers seat and starting with fuse #1 pulled each fuse, tested it with my meter, put it back in and went to the next. #45 was blown. Replaced the 10 amp fuse, turned the key on, everything lit up, started the truck the alternator put out about 14.2 Volts. Accelerator pedal responded nicely.

Thanks for all the qick replies and thanks for not telling me to go ahead a purchase a new PCM. I like that the troubleshooting tips started with the simplest things.

Charles

 

Thanks for getting back to us with the fix. #45 Ignition switch Run/Start feed .

I take it you were able to download an Owner's Manual.

 

Regarding the Owner's Manual and Diesel Supplement, I had those from downloading a couple of years ago when I bought the truck. My original post was referring to the service/shop manual (with wiring diagrams) as the thing that I didn't have and was using the one from my 1999 trucks. The changes from 1999 to 2002 were too numerous to correlate and I gave the fuse designations as an example.

Charles

 

Gotcha.