Recent Posts

11

Technical Support / Re: Motor shuts off while driving

« Last post by Fred Cook on January 27, 2026, 05:36:58 PM »

Fred,

I have had a similar issue where the coach power would occasionally disappear.  Play with the key and everything would eventually power back on.  I ended up unplugging the main harness behind the electrical bay and cleaning the pins on both sides with spray electrical  contact cleaner, soft brushes and mig tip cleaning rods. I used dielectric grease to help seal up both both haves and plugged the harness back together.  That has fixed my electrical gremlins for several years now.

I also bought a spare ignition cylinder to carry as a spare.  I have several keys to the old ignition switch so I won't swap it out until it starts failing if it ever does.  The ignitions are known to fail, or be temperamental all the way back to their use in Chevy's. Wiggling them to the exact spot it fails would be hard to do. Changing them out is easy just carry a paperclip.  I also have a spare door entry lock/latch since it is also known to fail.  If I every can't get in I will be grabbing a drill and drilling it out.

Hopefully this will help you some.
 

Thank you for providing your experience. I switched out the ignition switch this morning and the old one looked pretty much worn out. Won’t know if this is my problem until I get on the road in a couple of weeks to Dallas. I have a few people on other forms telling me they had the same problem with their motor shutting down and it turned out being a fuel pump relay in one case and an ignition relay in another situation. Others suggested tightening battery terminals, and check for loose ground wires. Very difficult to determine what’s going on here. I am trying to cover all bases before going on our trip. Very frustrating.

12

Technical Support / Re: Motor shuts off while driving

« Last post by Carl Boger on January 27, 2026, 12:06:33 AM »

Fred,

I have had a similar issue where the coach power would occasionally disappear.  Play with the key and everything would eventually power back on.  I ended up unplugging the main harness behind the electrical bay and cleaning the pins on both sides with spray electrical  contact cleaner, soft brushes and mig tip cleaning rods. I used dielectric grease to help seal up both both haves and plugged the harness back together.  That has fixed my electrical gremlins for several years now.

I also bought a spare ignition cylinder to carry as a spare.  I have several keys to the old ignition switch so I won't swap it out until it starts failing if it ever does.  The ignitions are known to fail, or be temperamental all the way back to their use in Chevy's. Wiggling them to the exact spot it fails would be hard to do. Changing them out is easy just carry a paperclip.  I also have a spare door entry lock/latch since it is also known to fail.  If I every can't get in I will be grabbing a drill and drilling it out.

Hopefully this will help you some.
 

13

Technical Support / Re: Motor shuts off while driving

« Last post by Fred Cook on January 26, 2026, 06:21:47 PM »

I have been lurking and learning much from this forum for a couple years now.  Thank you for all I have learned.  We experienced this same behavior driving through Montana, motor died, but would restart, then die again at random times.  Turns out it was the in-dash ignition switch, a unit used in 1970's vintage GM pickup trucks.  When continuity is lost, the engine shuts down as it is supposed to do when ignition is off.  Wiggle the key a bit, restart, and runs fine until the next bumpy bridge or whatever.  Replaced the switch with in-stock NAPA unit and has not happened again.  Avoid using a heavy batch of keys in your ignition switch.

I thought about the ignition switch too and bought a new one. But before changing it out I started the coach and wiggled the key around several times and it continued to run normally. Wouldn’t wiggling the key around make it lose continuity the same as hitting a bump?

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Technical Support / Re: Motor shuts off while driving

« Last post by Wayne Ogren on January 26, 2026, 05:30:30 PM »

I have been lurking and learning much from this forum for a couple years now.  Thank you for all I have learned.  We experienced this same behavior driving through Montana, motor died, but would restart, then die again at random times.  Turns out it was the in-dash ignition switch, a unit used in 1970's vintage GM pickup trucks.  When continuity is lost, the engine shuts down as it is supposed to do when ignition is off.  Wiggle the key a bit, restart, and runs fine until the next bumpy bridge or whatever.  Replaced the switch with in-stock NAPA unit and has not happened again.  Avoid using a heavy batch of keys in your ignition switch.

15

Technical Support / Re: Proper external charge hookup

« Last post by David T. Richelderfer on January 26, 2026, 03:29:17 AM »

When our inverter went on the fritz several years ago, I went out and purchased a charger that was 3-way selectable - a low amp maintenance setting, a 15 amp setting, and a 50 amp engine-starting setting.  So I hooked the red charger cable to where the inbound red cable from inside the coach connected to the first battery post, and connected the black charger cable to where the outbound black cable going back to the coach connected to the last battery post.  That way, I got all six of our 6V batteries charging at once.  I hope that makes sense to you.  lol

I recently had charging problems on my two 12V chassis batteries.  The darn Big Boy had been an increasing problem for a couple years, becoming intermittent in its operation.  So I hooked a jumper cable between the two connections on the Big Boy.  In the meantime, I ordered a new Big Boy and BIRD.  After replacing both the Big Boy and BIRD, the batteries are maintaining quite well.

16

Technical Support / Proper external charge hookup

« Last post by Joel Ashley on January 26, 2026, 02:34:15 AM »

Our inverter quit on me, probably the d*** squirrels nesting and evacuating atop it again, and it hadn’t been keeping the batteries up in storage.  Nor apparently was the solar system, even with the main switches off.  When I went in for my weekly check, I found the inverter’s remote with odd readouts I’d not seen before, not the usual state of charge one.  I couldn’t get the inverter to reset, so will likely have to remove, clean, open up, and hopefully repair its circuitry.

But I need to resurrect the 6v AGM battery set.  It’s been awhile, so refresh my memory about external charging them.  It’s the typical two 6v in series tied to another pair via parallel.  My 40 year-old DieHard charger kept kicking off after every 5 minutes, which it’s done before in my rarely driven F150.  So I got a modern “Noco Genius 10” charger and hooked it up tonight.  I assumed negative clamp to one battery’s -post and positive clamp to its series partner’s +post. 

I note the same voltage on both pairs, but is there another better hookup, like black clamp to -post of one series pair and red clamp to the +post of the second battery in the other series pair?  No difference, given they're tied together and there’s 12v among them regardless?  As such, I may have a long wait to finally top up, but won’t have to move the clamps to the second pair?

I should and used to know this stuff, but recent health circumstances often befouls my memory and logical processing.

Joel

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Misc RV Equipment for Sale or Wanted / Re: Batteries

« Last post by Zeb Severson on January 23, 2026, 09:32:44 PM »

Are these still available?

18

Technical Support / Re: 1991 Marquis - CAT 3176 - Engine Starting Problems

« Last post by Steve Huber on January 20, 2026, 10:00:16 PM »

Douglas,
All (to best of my knowledge) CAT outlets stopped servicing "over the road" engines in about 2023. They built their last OTR engine in the 2008 or so. If diesel shops have the CAT engine analyzer they should be able to track down any sensor of other issue that logs into the engine control unit.
The Engine Protection Override allows operators to temporarily bypass automatic engine shutdown systems caused by low oil pressure or high coolant temperature. So you are getting an error signal from one of those 2 sensors.
I think the tach problem is either a bad connection at the alternator or in the wiring from the alternator to the ECU and then to the tach. The other possibility is a faulty tach.
In case you haven't found it there is a wealth of knowledge (diagrams, manuals, schematics, etc covering 84-94 Beavers on Coach Assist. To access it log in on the Club website, select Technical, then Coach Assist. Then Factory Brochures. Then click on the 3 bars in the upper left of the screen. Select Beaver Coaches 1968-1994 and then Schematics.
Steve

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Technical Support / Re: 1991 Marquis - CAT 3176 - Engine Starting Problems

« Last post by Douglas Irvine on January 20, 2026, 03:16:10 PM »

Thanks Joel! Yeah I am hoping some of the vintage coach folks on here will see this eventually, or maybe Dave A. Unfortunately, I heard CAT shops have stopped servicing motorhomes. I get my parts and filters from Wyoming Machinery Co. Maybe I should call them and confirm if they have followed the national trend of CAT shops.

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Technical Support / Re: 1991 Marquis - CAT 3176 - Engine Starting Problems

« Last post by Joel Ashley on January 20, 2026, 12:14:51 AM »

I'm sorry no one has yet responded to your request for help, Doug.  We aren't all ignoring you, but like me most may not be familiar with your coach chassis or with Casper.   I initially thought your ignition solenoid was the culprit, a common starting one, but since your engine cranks that isn't likely.  More so is a fuel delivery or, as you suspect, a sensor issue;  not my area of expertise for sure;  and I've not heard of an "Engine Protection Overide" switch. 

But the repair services guide that the Club maintains does list one Casper area facility that a Club member had positive results from: Wyoming Machinery:
https://www.wyomingcat.com/company-locations/casper/

You can find the RV Service Providers guide within the Members Only section on the Forum's Home page.

This person's was an experience from several years ago, and especially since Covid, as you know many companies have changed.  But it may be worth a call/visit.  I wish I could be of more assistance myself, but can only hope that between that link and another more experienced member's reply, you get this annoying problem resolved.

-Joel