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Topic: Update on the sense wire near fire (split from Re: What did you do to your coach today) (Read 648 times) previous topic - next topic

Update on the sense wire near fire (split from Re: What did you do to your coach today)

Some of you may remember the loose sense wire (that we could not find when we replaced the alternator) that fell out of the corrugated wiring bundle and shorted out against the engine last fall. This wire created enough heat to melt many of the wires in the engine room; we think some 20 wires were affected in one way or the other. Right after it happened the weather turned cold (winter, ya know) and since the coach (1993 U225) is outside we decided to delay any repairs until we had warmer weather.

Last week the weather moved in the 70s for a few days that luckily coincided with spring break so Sue was off work from the school district. We managed to trace and repair 9 wires in the engine room over 3 days of working. Doesn't sound like much but we had to ring out the wires to make sure we had the right ones (insulation burned/stuck together), cut a wire to splice to the two ends of what was still good, and then heat gun the butt splices to make them waterproof. All upside down and sideways, etc. Quite a job for us... probably nothing for a 20-something. LOL

We were lucky that none of the melted wiring led into the coach itself so all damage was isolated to the engine area where we could, at least, get to it. But we discovered that much more of the wiring was damaged than we had, at first, estimated.

After the 3rd day our weather reverted to mid 50s temperatures, 18kts of wind and scattered (or, sometimes, not so scattered) rain. Since this was only one of our spring chores we moved on and will resume the job when the weather warms up again... in a week or two.

Then, of course, we have to face the "won't go into reverse" problem which was what we were doing when the entire business began.

I would like to again caution all owners to fuse that sense wire. In our 1993 coach it leads directly from the isolator panel (above the driver's side mud flap in the engine room - open to the elements) with no fusing whatsoever. It's a #14 wire and can heat up a whole bunch if it shorts out.

Craig
1993 U225 36' Unihome GV with PACBRAKE exhaust retarder, Banks Stinger and Solar Panels.
Toad: 1999 Jeep Wrangler 2-door soft-top.

"No one has ever had to evacuate a city because the solar panels broke."

Re: Update on the sense wire near fire (split from Re: What did you do to your coach today)

Reply #1 –
Quote from: wa_desert_rat –
Some of you may remember the loose sense wire (that we could not find when we replaced the alternator) that fell out of the corrugated wiring bundle and shorted out against the engine last fall.

Electrical Fire in the Engine Compartment
Learn every day, but especially from the experiences of others. It's cheaper!  - John C. Bogle

2000 U320 36' non-slide / WildEBeest Rescue
2003 U320

Re: Update on the sense wire near fire (split from Re: What did you do to your coach today)

Reply #2 –
Thank you, Michelle. :)

Craig
1993 U225 36' Unihome GV with PACBRAKE exhaust retarder, Banks Stinger and Solar Panels.
Toad: 1999 Jeep Wrangler 2-door soft-top.

"No one has ever had to evacuate a city because the solar panels broke."

Re: Update on the sense wire near fire (split from Re: What did you do to your coach today)

Reply #3 –
Craig, I had wondered how you were coming along with that project.  And yes, I understand the sense wire, On mine it had been redirected when some misguided mechanic ( loose definition ) had tried to rewire the alternator, it shorted and luckily the wire was protected by a circuit breaker in the main wiring panel.
Good luck and I hope you are on the road soon.
Gary B

Re: Update on the sense wire near fire (split from Re: What did you do to your coach today)

Reply #4 –
You guys are scaring me!!!  Had what appeared to be a weak alternator and at the last service, I mentioned it.  They found a wire that can came seperated and was just hanging,  Hooked it back up and everything appeared "fine".  Now I have to go looking to make sure all is proper.
1994 U225
build #4514
 

Re: Update on the sense wire near fire (split from Re: What did you do to your coach today)

Reply #5 –
Patc, Be careful when tightening and checking wires at the back of the alternator or at the isolator, if you ground the positive you may get a fireworks show and need a clean pair of drawers.  Always a good idea to disconnect the battery grounds when doing things like this. (  I said it was a good idea, not that I always do it. :) )
Gary B