Wednesday, February 19, 2014

Workshop Wednesday-Short Fuse

 Nothing happened on my bikes since sunday. Monday was a 15 hour day in the truck pushing snow and tuesday was a bit more plowing and then I spent some time working on a fork lift. This particular fork lift is a repeat in I fixed it for a "no start" problem last week with a tune up. The machine has over 32,000 hours on it and the cap and rotor may have been original. Well probably not but they were bad.  Cap, rotor, plugs and wires and she ran great. We trailered it back to the customer but the next day we got a call. "No start". This time it was a starter issue. The nose cone broke off the starter. I replaced the starter and noticed the flex plate seemed to move out of center just a bit. There were no cracks or loose bolts in the plate so it went back together. Yesterday I got a call..."no start". Ru ro Shaggy, I thought, but this time it was an issue where you would turn the key and nothing happened.
 I threw some tools in a box and headed over there. Jump the starter, cranks fine. Turn key to start, dash lights change so I assume key is good. No power at solenoid so I'm thinking seat switch or neutral switch. Huh, no seat switch. I'll just run the test light over all the fuses to make sure the basics are covered. Yep, all test ok.
 Man the insulation is crap on this wire harness. Cracked and brittle with some wires exposed. I spend an hour replacing some junk wiring and found a pair of loose wires twisted together just hangin there. Must have been for a seat switch. I sorted those out and I thought I was onto something because now she cranks! I'll just try it again to be crank. Huh. Holding the key in start position and wiggling the wire harness proved to me there was an intermittent connection somewhere. Good luck finding it. I was having flash backs to last year when a similar problem kicked my ass. Hard.
 I tried separating as many sections of the harness as possible to pin point the area where the break was. This can be frustrating but after about half an hour of dinkin around I discovered the problem. I discovered it because I rechecked everything and what I found was this:

 Are you freakin kidding me? When the wire harness was flexed just right that little broken section of fuse was making contact. When it flexed the other way the fuse acted like it was blown. Of course when I checked it the first time it was acting normal.
 I walked out to my truck, opened the fuse panel and stole a 10 amp fuse. I put it in the forklift and all my troubles were gone.
 Back at the shop Al told me a story about a plow light problem he had recently with a similar fuse issue. I know I've seen this before but its not something you think about when doing tests on a electrical system with so many crappy wires and years of different repairs and splices in the harness.
 So what did we learn here? Nothing really. I could say that to assume only makes ans ASS out of U and ME but really when trying to quickly diagnose a problem like this a little assuming is in order. Only after no other problem is found should we go back and confirm all those assumptions.
 Tomorrow they're calling for more snow to hit the ground,
  I'll spend the day pushing it around.
Next time a fork lift gremlin is giving me the blues,
 I'll be sure to double check every fuse!
Er no?


  1. I've never had this happen to me but I've heard of it a few times now, enough at least to add it to the checklist.

  2. Occam's Razor (look it up) LOL. When you hear hoofbeats think Horses, not Zebras. Bill Wood

  3. Ah yes, it was easy to assume the simplest problem was a blown fuse. Thats why I tested them. Too bad the intermittent problem tested ok at the instant I was messing with it. I had to fall back on a different principal. "If at first you don't succeed, try try again" which has to be carefully integrated with the fact they're paying me by the hour and want results soon! Thanks for the post, Bill.

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