Friday afternoon after a trip to town, total 25 miles, I turned off my engine and it won't restart or crank. Batteries are strong, connections clean. It's blowing a 40 amp fuse labeled "IGN RUN". I swapped a fuse from another spot and blew it immediately. Removed the starter and tested it with jumper cables; it ran fine. I disassembled the starter and it looks fine except for significant wear of one of the copper contacts like I've seen pics of on this forum. Brushes still fat. Commutator a little glazed, so I cleaned it and will get new contacts, but I don't think the starter is the problem. Other electrical functions seem all right. Any suggestions are welcomed.
Steve
97 2500 5.9 12-valve, 110,000 miles

 

it sounds like somethings grounding out. iirc there is a small wire that goes to the starter which i believe is red. check to see if the insulator wore through and it grounding out on anything.

 

Try it without the starter connected and see if the fuse still blows.

 

Thanks for those ideas. I'll check them out in the morning. I did not inspect the entire length of the wires yet. I did check the fuse terminal for continuity with ground and it was not grounded, at least at the moment when I checked it.
Steve

 

How about the fuel shutoff solenoid? There is some relation with the starter contacts and the fuel solenoid.

 

Thanks, Traindrv, I'm checking the fuel shutoff solenoid right now. I removed the remote fuel filter to get access, and the battery is out of the way. Yesterday I got new starter contacts and will reassemble and install the
starter today, but I have to go to work in about an hour. I'm looking in the shop manual to find out how to check the solenoid. I take some of the stuff in the manual with a grain of salt. For example, it says there is no servicing the starter except by replacing the entire starter assembly. If a contact wears out like one of mine looked about to go, the standard dealership procedure is
" Replace the whole assembly." I expect to have mine ready for another 100 k miles or more by installing the contacts for $10.
Steve

 

Been thinking of putting the heavy contacts in that are availible but unless they screw up that will have to wait until spring. Good Luck

 

The lift up portion of the solenoid which the starter triggers has it's power supplied by a blue fusible link wire straight off the battery positive.
Highly doubt that would the problem unless the solenoid relay is messing up.
Just unplug the relay and see if your fuse still blows.

 

Thanks, Bill, I'll try that in the morning. I still have to reassemble and install the starter with its new contacts and put the batteries back. BTW I just learned today that the right side battery is only for the intake air heater. I've also been reading the shop manual about other things involved in starting, looking for whatever it is that's shorting out.
Steve

 

What???????? The batteries are hooked together, they work together. That is why you should change them both out at the same time. I'd trash that manual, the BS in it will draw flies.

 

Interesting observation you make... The following paragraph is repeated 4 times in the 14 pages of the "Battery Diagnosis and Testing" section:
"Note: Models equipped with the diesel engine option are equipped with two 12-volt batteries, connected in parallel (positive-to-positive/negative-to-negative). The secondary battery, on the passenger side, is dedicated to providing current for the operation of the intake manifold air heater. The primary battery, on the driver side, is dedicated to all other vehicle electrical
requirements. In order to ensure accurate diagnostic results, these batteries MUST be disconnected from each other, as well as from the vehicle electrical system, when being tested."
An even longer paragraph, warning about explosive gases, acid, etc. is repeated SIX times in the same 14 pages. Maybe this is why the manual is almost 3 inches thick. Maybe the guy who wrote it owns stock in a paper company.
It would be interesting to find out how they train the electrons from each battery to stick to their assigned tasks, and not fraternize.
Steve

 

Sounds like somebody doesn't understand basic electricity.

 

Every accessory on the truck is connected to the poles on the drivers side battery, including the grid heaters. Unreal.

 

It makes no difference since the two batteries are connected together with heavy cable.

 

The truck is running again! That's the good part. The other part is, I don't know what was wrong that caused the fuse to blow last week. I did replace the starter contacts, but the starter bench-tested OK before I opened it up. I checked the starter relay and the fuel shutoff relay and looked around for chafed wires and such. I disconnected the manifold air heaters and starter and turned the key and the fuse didn't blow; then I connected the starter and started the engine with no problem. Then I reconnected the air heaters and started the engine again. I sure would like to find an explanation for it. I'd like to feel confident it isn't likely to fail again in a less convenient place. In my work I often go to some such places, some without cell phone signal...
Thanks for all the input above.
Steve