Wiring and alternator issue

[Brian Chavet]

Hello all,

Need some help with this one. While on a trip, my voltage dropped to around 9 volts. Took it to a Freightliner Service center in Billings, MT where they determined the alternator was bad. Replaced the alternator and went down the road. Within 6 hours I was right back where we started, about 9.2 volts. Have it at another service center in Spokane, WA where they discovered the damaged wiring in the attached photo. Anyone know what this cable is for and what may have caused this? They believe that whatever is going on here shorted out the new alternator just like it did the old one. 2000 Marquis, C12 425 hp.

[Steve Huber Co-Admin]

Brian,
Where is the solenoid located? Based on cable size it doesn't appear to be the Coach Power or Battery Boost solenoid. There may be some labeling on the wires running to it if the heat hasn't affected it.
Steve

[Eric Maclean]

Brain
As Steve said if you wipe the dirt from the wires they would be labeled I can almost read it in the picture when I enlarge it but there too dirty to read.
It looks like some sort of auxillary or accessory solenoid how ever the brown wire is not likely a Beaver addition as they used white wires most of the time it appears that it is the wire with the short by the look of the burn pattern I would follow it to see where the burn stops . Don't be surprised if it is worn through on something either way it should have been fused to avoid what has happened hopefully it didn't burn more wires .
It could have burnt the whole coach bad news.
You should be able to disconnect the wires and use an ohm meter to ground to find which one is shorter.
It's going to be a big job but all those wires will have to be inspected for signs of burnt or compromised insulation.
Hope this helps
Eric

[Steve Huber Co-Admin]

Brian,
If I had to guess I'd say it was the fan solenoid. Eric's correct in that the toasted wire looks like an add by a PO (thus no labeling). I suspect you will find constant 12v on that terminal (ignition probably needs to be on). The shop should have a toner https://www.amazon.com/s?k=wire+toner+tracer&crid=2S4Q44AJT6BCS&sprefix=wire+toner%2Caps%2C299&ref=nb_sb_ss_i_3_10 that they can use to trace where the wire goes. If you/they are unable to trace it, consider disconnecting it and seeing what doesn't work .
Steve

[Eric Maclean]

 Steve I think your right I think that side of the solenoid is live .
Is it possible that this is the auxillary starter solenoid like on the earlier Magnum chassis ?
If so the original wire on the live side likely goes to the starter battery terminal on the starter( no fuse) !
And the other large wire on the other side of the solenoid goes to the starter solenoid on the starter.
The burnt wire is anybody's guess.
Eric,

[Steve Huber Co-Admin]

Eric,
I initially thought that it was the starter solenoid but decided against it based on the wire awg. It seems light for a starter.
Steve

[Fred Brooks]

   Guys, I have a 2000 Marquis Jasper built in April of 2000 and have not seen that yet. I'll go and look in the morning, It does look like the trigger solenoid for the starter solenoid (on the starter itself). Fred

[Eric Maclean]

Steve
I think it's a primary solenoid or trigger solenoid as Fred calls it .
It is used to supply the trigger current for the starter solenoid
Likely15 to 20 amps the reason they use them is it facilitates the rear start controls and helps elevate the volt drop caused by the length of wire from ignition switch to solenoid over 40 feet the smaller solenoid draws less and provides a better trigger signal to the starter solenoid for a more reliable operation and extended starter solenoid life.
Eric

[George Harwell]

As mentioned above it definitely resembles a trigger solenoid. My 03 Monterey CUMMINS powered has the solenoid mounted on a frame outrigger in the engine bay. Didn’t know it was there until it failed and I had to change it.

[Fred Brooks]

   Brian,
  Well I spent about a half hour crawling around under my Jasper and there is no Cole-Hersey style 80 amp continuous duty solenoid to be found on my coach. I even opened the hatch between the closet and bed......zip. Maybe you could tell us where your solenoid is located with reference pictures. Thanks, Fred

[Steve Huber Co-Admin]

While interesting, the solenoid's purpose does not appear to be the issue Brian is having with his coach. The problem is what is on the other end of the toasted wire. Hopefully he will let us know that and also provide a bit more info on the location of the solenoid.
Steve

[Brian Chavet]

Hi all, sorry for the delay. Just got back from this "vacation" after leaving the coach at Beaver in Bend (gulp), loaded what we could in my Yukon, and limped on home, tail between legs. I don't have the ability to work on this stuff any longer because of my back. This is located on the aft outboard side of the battery box. So I think you're right about the function. I will let you all know what the final diagnosis and fix is after my service appointment (11/17). I think this is the final straw, going to put it up for sale when I get it back now that everything is fixed. Spent a small mountain of money on this trip and didn't do a single thing but mess with the coach, wife isn't happy.

Thank you all for your input!