Engine Ignition Feed fuse blows
 

Greetings all,
My Engine Ignition Feed 20 A fuse keeps blowing. Any hints on most likely way of narrowing down why?
If it helps, The volt meter drops form about 14.5 to 12.5 v seemingly when this happens.
The fuse trips just prior to the starter being engaged on the turning of the key only. The ignition switch and key tumbler test fine.
Thanks,
Jon
1998 H1 6.5 Turbo Diesel.

Do you wait for the glow plug controller to finish its blinking cycle? Then, turn the ignition key to engage the starter? I think it is important to determine if the current draw from the GPC and starter are at different times or the same time; it may make a difference. Do you have anything else ON when you start the truck that could be a big current draw; ie: large amplifier for stereo, lights?

GH

Thanks for your reply,
I've tried pulling fuses from the glow plug controller, fuel pump, lights, etc, and it still blows.
Jon

I would disconnect the starter at the starter. Turn the key and see what happens. My guess is the fuse WILL NOT blow. If this is true, you have a short in the starter itself. Hopefully, in the Solenoid rather than in a turning on the motor itself You can get a non-sealed light weight NAPA starter motor which will work in this truck or rebuild yours.

Gil

Great, makes sense, I'll give it a go

Darn! No joy.
Disconnected the starter and same fuse blows.
I tried pulling the starter relay and same.
Relay tests fine to my limited ability:
0 ohms between pins 30 and 87a.
80 ohms between pins 85 and 86. Remainder open.

Ignition switch test fine (I even tried replacing it) as does the ignition cylinder.

Well I found out how to pull the fuse box without breaking it. It was gentle screwdrivers to disengage the latches, but in the opposite direction I was expecting.
Sadly that was not the source of my problem. No shorts or even chaffed wires.
Does anyone know if there is a reasonable way of testing the voltage regulator without pulling the alternator (outside of paying someone else to do it I mean)?
Is the PCM a possible culprit? For some reason a prior owner (or likely aftermarket electronics installer) beat the outside of the PCM like it insulted their mother, but I don't have the capability of testing it.
Regards,
Jon

I'm having the same issue.. Fuse 7B keeps blowing, Can't figure out where the short is...

The darn fuse stopped blowing for a couple of months and just started doing the same thing again. It started a few days after a heavy rain (I live in the Mohave, so heavy rain is not common). I wonder if it is water getting into the harness or an individual component.
This all started after a storm last year, so it is a possibility.
I start searching wires and let you know if I find anything.