So I recently started having an issue with my early 1999 F450. I have searched endlessly and found no solution. I hope you guys can help!!

About a week ago my truck would act like you shut the key off, and turned it on again instantly. Before I could react the episode was over. When looking at the dash after, the wait to start light would be on, indicating the PCM lost power. The issue was the number 24 fuse under the hood, it had a hairline blow in it, which I think cause it to still allow current, but would cut out randomly. I replaced it and it was fine for 100 miles then it blew again. This time it just shut off and would not start. I changed the fuse and headed home. I have checked all of the sensors and connectors, nothing is burnt out or chaffed. The harness where it crosses the valve cover is also not damaged. It has a new CPS, ICP, batteries, and I cleaned all of the terminals for the glow plug relay.

The SES light is on for P1391 and P1393, which are low input voltage for glow plug bank 1, while the other code is the same for bank 2. These came on when I put the engine back in last month after doing a manual swap. I cleaned the terminals and it hasn't gone away. If I clear the codes the light goes out for a couple minutes and comes on again.

The clock spring is bad, I don't think that's the problem but I don't know what else may be on that fuse, I'll list it.

Also for a few months if I really step on it it may seem like it is cutting out, like the sensor for the throttle pedal is bad. When it started happening I swapped it with a spare I had and was no different.

Thanks in advance for any advice, I genuinely appreciate the help as I have found no leads in my research.

Also, this is the #24 fuse under the hood, not the #30 that blows when the fuel bowl heater shorts out. (Unplugged on my truck)

 

I'm assuming still same problems from this thread
https://www.ford-trucks.com/forums/1...lug-issue.html

Have you pulled the fuse box under the hood and looked at the wires going to the back of it? Suggest disconnecting both batteries before doing this.

Did you ever try swapping out the PCM power relay?

 

I took the box out and looked at the wires, it's a little hard to tell but they all look fine.

 

I switched it while trying to diagnose it the first time, I will switch the relay again and see if it blows still

 

Where is the plug that is unplugged for the fuel bowl heater? Is it possible its grounding out in a pile of goo? When my fuel bowl heater went out, it took fuse 24 as well under the hood.

 

Yes I checked it, it seems to be fine. It occurred to me that when I swapped trannys I just zip tired all of the unneeded wires for the manual out of the way, maybe it is rubbing and chaffed a wire. I will check tonight

 

Found it!! The harness had fallen out of place and was rubbing on the front driveshaft mount on the transfer case. It had rubbed through a couple wires so I put liquid electrical tape over them and tied the harness up better. Thanks for the help!!

 

That's great. Glad you got it fixed and thanks for following up so others will be able to see the info in the future.