My 99 500 4x4 keeps blowing the 30 amp starter relay fuse. Sometimes it lasts an hour, sometimes a few days but I can't figure out what is causing the problem.

Any ideas how to troubleshoot?

Thanks for any input.

 

Does it blow while you are cranking, or while you are riding? While cranking something is drawing to much current. If while riding I would suspect a wire with the insulation worn and touchs the frame while vibrating and banging around The cranking is easy, the other is a PIA.

 

It has never happened while cranking, only while riding.

 

Its not easy, but heres how id do it.
Get a test light, home dump and lowes has them, it just a small bulb with two aligator clips on it. About a buck and a half. Take out the fuse and put the test light across the fuse terminals. Go to key on, and the light should stay off, becuase normally there is no current flowing in this condition.. Now go wiggle connectors and wire bundles, until the light comes on (meaning the circuit shorted out). It could be a connector full of water, or a wire rubbed bare, and touching metal. I suppose it could even be the starter itself, but i wouldnt think it would be interminent if it was the starter. It will be on the power side of circuit (before the load), it wont be on the ground side of circuit.
Itll help if you have a skematic, for the wiring.

 

In addition to checking the wires for shirts as Hondabuster suggested, if you have a winch check the winch relay switch and winch for dirty connections and shorts. I had a similar problem on my TRV and the winch relay was coroded up and shorting out.

Cleaned it up and coated it with dielcectric grease and have not had the problem.

I also seem to remember someone posting about finding a short next to the frame in the wiring harness where the fuel tank or something rubbed through a wire causing a similar problem.

Hope this helps
SJ

 

I do have a test light but am pretty illiterate when it comes to electrical. I will try you suggestions this weekend and see what I can find.

Thanks for your help!