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FLNavyVet

Monaco Diplomat Stalled While Driving

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We have a 2002 Monaco Diplomat 40PBT with the Cummins ISC engine. Last night on the way home from a trip, it died while driving. It had been running fine with no issues and without warning, the dash chimed, the lights on the indicator panel all went out, engine died and lost power steering. I was able to coast it to a safe spot. Though the engine stalled, the generator continued to run fine.

We checked all the fluid level, rechecked the sliders, checked the battery voltage and everything looked fine. Both the house and chassis batteries were fully charged, so it didn't appear to an alternator issue. We still had over 1/2 tank of fuel. The fuel filters and fuel/water filter had all been changed within the last 1000 miles. We tried to disconnect the batteries and let it sit for a while then try to start it up. Nothing. No chimes or lights on the dash when the key was turned on, it was simply dead. Fuses and everything looked good.

We finally resorted to having the coach towed home - ironically, it had died turning into our community, so the tow was about 300 yards! I tried it one more time to see if she would power up and nothing as before.

This morning I went out to the coach to get something and tried to start it up. She started right up and purrs like she usually does. Everything seems to be fine this AM. I haven't driven it yet though.

Any thoughts or ideas on the cause? Not feeling comfortable with the idea of driving it without knowing what happened. While doing some research online this morning, I saw two references to issues similar to this where the owner stated a 'weak relay' was changed, but no indication of which relay it was.

Thanks in advance for any help!

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FLNavyVet,

Welcome to the FMCA Forum.

Did everything that normally works with the ignition on quit at the same time-- things like the dash HVAC fan?

If so, suspect the ignition solenoid or ignition switch or wiring between them. The solenoids are a fairly high failure rate item.

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Thanks for the welcome and reply.

The swtich seems to be fine, I did jossle it around last during the troubleshooting. We don't run the dash HVAC so I am not sure on the fans there. When it died, the whole indicator panel went out and the gauges didn't work. When turning the key back on, it was as if the power was simply out.

That said, the running lights, headlights, interior lights, etc all stayed on and working.

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FLNavyVet,

Welcome to the Forum Also!!

I will ditto Brett's response, regarding the ignition solenoid. They do fail and the fact that its 10 plus years old would be my first thought.

Good part was that you where close to home and able to move safely off the road.

Rich.

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I will ditto Brett's response, regarding the ignition solenoid. They do fail and the fact that its 10 plus years old would be my first thought.

Do you know if the ignition solenoid is in the front compartment with the fuses, with the batteries or in the engine area?

Thanks everyone!

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Generally in the front compartment with the fuses. Because the many things that only work with the key on would well overload what could reasonably be run through the ignition switch, the ignition switch is just used to close the IGNITION SOLENOID with all items normally powered with the ignition on supplied from it.

Another indicator of a failure here would be that the Allison shift pad would be dark (it is powered by the ignition solenoid.

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Thanks Wolfe10. Good info to look for with the shift pad if it happens again.

One of the things I have been trying to find is a list of what would prevent the solenoid from operating. I figured out that the slider locks prevent the system from working (the hard way :wacko: ). When that happened the system had a similar condition in that the indicator panel wouldn't illuminate and it appeared to simply be dead. We ran the sliders out and back in and it all worked. Not the case this time. So given that this the second time we had an issue like this, wanted to see if there was a list or known items that would prevent the ignition/indicators from working.

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I have heard of a few Monaco coaches have trouble with the manual chassis 12 volt cut off switches in the rear fuse bay vibrating loose inside causing that condition.

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Cummins engines have a 135 amp circuit breaker located near the engine, on Freightliner chassis it is located on the drivers side attached to the frame behind the axle. It is a 3" or so breaker with two heavy cables attached and at least one 4-8" guage wire attached. The smaller wire provides current for dash and a signal to relay in front to close and provide power. Don't be confused by a similar looking circuit breaker on the other side of the engine in roughly the same place, this is for the start up heater for the engine. The precise event you described happened to me and it was a loose signal wire on the circuit breaker i just described.

Due to proximity to road film, water, dirt etc. this device has a high failure rate and needs to be cleaned and protected from corrosion frequently. You can test the breaker by bypassing it with a jumper and see if your dash becomes functional again. (Do not try to start engine with bypass wire in place).

If so that is the problem. Freightliner told me that in a emergency you can bypass the breaker by putting both heavy leads together on one terminal to get home or to a repair facility. This will not hurt anything as long as you do not have other problems. They also recommended that it might not be a bad idea to carry a spare breaker. Replacement is a ten minute job but the part is not available in auto parts stores, and many Cummins dealers don't stock the part.

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Sherry, Welcome to the FMCA Forum!

I did read your post on the electrical thread, but I'm not well versed with your chassis, but you cleared up some items. 

You mentioned that everything works normal when the key is turned on (Correct) ? If that is the case, then there is the possibility of a bad relay that is energized when you turn the key to the start position. This relay is energized only in start and is located in the rear of the coach close to the starter. If you are traveling with a companion - have that person turn the key to start position and count 1000-1 release the key repeat at1000-2 and keep repeating while the other person listens for a clicking sound. No click then this relay has an open with on the small terminal(s)  If you hear a click or if while you are performing the test and the engine tries to start. The relay is failing-this relay sends power to the starter solenoid. and this solenoid engages the starter. Should you hear a loud click and the engine does not start. Then the starter motor has most likely failed.

Check out the items listed and post any and all results.

Now, if items do not work when you turn the key only to the run position, it id the run solenoid that has failed.    

Rich.

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Navy Vet,

Welcome. Yes the solenoid are in the front compartment drivers side. There are two of them and they are 12 volt constant duty solenoids. Take a volt meter and with the key on check voltage on both large terminals. With the key on, all four terminals should read 12 volts. If neither reads 12 volts on both lugs check the small terminal for 12 volt. 12 volts= bad solenoid, no 12 volts you need to look reason for no power. When you find power go back and recheck the solenoid.

Herman 

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FWIW, we were driving our 2004 Knight ISC on an Interstate when all of a sudden engine and instrument panel died.  Fortunately was able to coast to an exit ramp.  After much searching and head scratching, I noticed the 2 heavy cables going to the chassis battery disconnect switch were a little loose,  Switch looked OK, but took its cover off to check the cable tightness.  When I did that, the switch fell apart in my hands!  Bolted the 2 heavy cables together, bypassing the disconnect switch, and we were on our way with no further problems.  My guess is that the switch was overtightened when initially installed stressing the switch which ultimately caused it to fail..As an aside, I found an exact replacement switch at WalMart online of all places.  I installed the new switch carefully to avoid stressing it.  It's a marine switch made in New Zealand.

 

Gene M

 

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