2002 Diplomat Dies While Driving

[fountaincharles2]

My Coach has a recurring problem while traveling down the Interstate of totally losing all power to the Dash Board(including tranny), it just stops running until it cools, then restarts. Last Saturday(after driving 362 miles) I sat on the side of the Interstate about 1 1/2 hours before it decided to restart. I had this problem about two years ago and found/replaced the three relays and sockets in the Front Drivers side compartment/large circuit board(original ones had partially melted). All has been well until Saturday. These replaced relays were cool to the touch when it first shut down last Saturday, so I suppose the original problem was not located/repaired as I thought 2 years ago. The chassis battery cable coming to that compartment/Board still had 12.5 volts showing on my volt meter. However, those familiar with this Board knows that the three relays, Ignition, Accessory and Lights, have a row of fuses just above these relays. None of these fuses had power on them. However, in the lower left corner of the circuit board, there is a resettable breaker(50 amp as I recall) that I didn't think to check while the system was dead. And of course I wouldn't be able to tell now since the system has since cooled and is working until it gets hot again. 

In any event, spent the Saturday night in an adjacent Walmart parking lot(1/4 mile from where it died), then Sunday morning started right up and drove 100 miles on home without further incident.

[dickandlois]

David, Could you post the relay you replaced that where melted / The number and location information would also help. Think you are referring to the fuse panel in the outside bay - drivers side.      I think they are all in the start/run circuits. 

Did any of the ACC items work?, like the heater blower motor and windshield fans, Windshield wipers, turn signals / 4 way flashers?

Rich.

[hermanmullins]

David,

You mentioned waiting for it to cool down. What are your coolant levels? How about your oil level? Both will cause your engine to shut down if the levels are too low.

Herman

[dickandlois]

Herman, Good points, but he did not mention any check engine lights coming on.

Rich

[wolfe10]

Rich,

Assume you are thinking about the IGNITION SOLENOID for the signal from the ignition switch to it.

[dickandlois]

27 minutes ago, wolfe10 said:

Rich,

Assume you are thinking about the IGNITION SOLENOID for the signal from the ignition switch to it. Not the issue should be inactive while on the road? <but that solenoid should be hot from another fuse point, not the 50 amp fuse mentioned. That problem tends to sound like a short under the panel that the relays are mounted on. Wires shorting to the metal underneath the the relays and fuses. ???? 

Kind Of ! The other key point was the damaged relays and sockets that where replaced. 

Leaning towards some chaffed or damaged cable(s). The coach is almost 18 years old.  

The starting relay current should only draw current in start. while on the road what would draw enough current to trip the 50 amp auto rest breaker? and what ACC where powered on when it shut down? smaller fuses all OK and he still had 12 vols on the supply side of the 50 Amp fuse. that info should narrow down the problem.

Rich.

Note I do not have the OEM electrical drawings for his model year just some photos.

 

[fountaincharles2]

That Board is enclosed inside a plastic box and has a tight lid to keep water and dust out of it. There is nothing behind the Board to touch any of the actual circuit runs. So I don't believe the problem is in the Traces. When I had the Board out 2 years ago, there was not sign of damage to the back or around the melted sockets. I would post a picture of the Board, but I don't know how to attach it on this page.

As far as fluid levels....every thing looked good just before it quit. And before I stated home I checked oil, etc, so I am hard pressed at this point to understand how a sensor would kill all the power to the dash. 

In addition, the dash fans continue to operate, headlights, emergency flashers, etc. But the dash as well as the tranny panel were all dead.

 I will try and see if DW can assist me in attaching a picture of the Circuit Board.

Edited March 3, 2020 by fountaindavid.jean
attach photo

[fountaincharles2]

This is a picture of the Board out of the plastic box and this was the condition when I first had a problem two years ago.. The Peach colored wire is what I used to get the MH to my residence when it first broke down 2 years ago. The three melted sockets are the ones that were replaced with heavy duty versions. The chassis battery stud still had 12 volts on it shortly after everything died. The back of the Board looks as good as the front with no burnt places.

[wildebill308]

Ok, I bet you have already looked at this, but. Have you cleaned and tightened all the ground connections? It sounds like something's heating up and losing connection then cooling down and reconnecting. So tightening all connections and especially ground connections would be where I would start.

Bill

[manholt]

I take it you also replaced the little red wire on the isolator?

[dickandlois]

2 hours ago, fountaindavid.jean said:

This is a picture of the Board out of the plastic box and this was the condition when I first had a problem two years ago.. The Peach colored wire is what I used to get the MH to my residence when it first broke down 2 years ago. The three melted sockets are the ones that were replaced with heavy duty versions. The chassis battery stud still had 12 volts on it shortly after everything died. The back of the Board looks as good as the front with no burnt places.

David, The picture shows the Solenoid on page 307 in the manual link I sent you in a PM of the manual link. The page offers some info on what it does.

Bills thought regarding a loose ground is a good one. Grounds are one of the most common electrical bugs.

Rich 

[fountaincharles2]

I have not replaced any of the wires. All I did was remove what was needed to get the Board out of the plastic box so the bad sockets could be removed/replaced. As far as ground wires, as I remember, there are no single ground wires connected directly to the Board. I could be in error on this. When the unit was dead, I did find a ground lug, but don't remember the exact location. I will try and check that tomorrow. 

[dickandlois]

2 hours ago, fountaindavid.jean said:

This is a picture of the Board out of the plastic box and this was the condition when I first had a problem two years ago.. The Peach colored wire is what I used to get the MH to my residence when it first broke down 2 years ago. The three melted sockets are the ones that were replaced with heavy duty versions. The chassis battery stud still had 12 volts on it shortly after everything died. The back of the Board looks as good as the front with no burnt places.

Dave I'm trying to read the part number of the board. Think it is 1561507 Rev. A   Is that correct?

Rich.

[fountaincharles2]

Rich, is it possible that what appears to be a starter relay(page 307) could be wired in such a way as to kill all of the power to the ignition switch/dash panel??

[fountaincharles2]

The Board P/N is 16615059 rev A.

[fountaincharles2]

These Boards are no longer Manufactured. When Monaco went under, the company that bought them out also has/owns the rights to all of these designs. Since there is no real/high demand for these,  the current Monaco Manufacturer does not have them made anymore. 

[dickandlois]

Thanks for the correct number and Yes it is a key power connection for the circuits that are loosing  power. The trick is to find out why. The solenoid  could be the issue when it heats up, but I do not want you to go out and find a replacement yet. 

What was the outside ambient temperature around the time it failed /meaning the board?

Rich

[fountaincharles2]

Outside temp....It probably was about 50 degrees or so. About 4 pm. No sure what the temp of the Board was. But it is in a closed environment. None of the dash wiring was hot nor the ignition key wiring.

[dickandlois]

43 minutes ago, fountaindavid.jean said:

Outside temp....It probably was about 50 degrees or so. About 4 pm. No sure what the temp of the Board was. But it is in a closed environment. None of the dash wiring was hot nor the ignition key wiring.

Thanks Dave! Think we can put that part on the back shelf for now. Wondering if the problem could be in the circuit that supplies power to the energize the coil that closes the continuously energized coil. Sometimes engineers design the supply circuit voltage to decrease, once the item is in the latched mode to reduce the hear generated in the coil?   Sometimes the solution is not a straight line.

As I mentioned to Brett, I do not have the wiring PDF's , but have some pictures of the wiring PDF files. Better then nothing. The information is hard to read, like the part number you corrected for me.

You can test that thought with a meter, but the problem might be in the wiring running from that 50 amp Auto reset circuit breaker. You did mention you had power at the fuse in question. Could be a loose connection between it and the contact terminal on the board feeding the solenoid,  on the board. Thick it was Carl that questioned that short and (maybe 2 gauge wire between the board terminal ) . So check the crimp connections with an Ohm meter to see if it is one of the crimps is loose or the wire is at fault !

Nothing like long distance trouble shooting ! LOL

Rich.

[kaypsmith]

1 hour ago, fountaindavid.jean said:

Rich, is it possible that what appears to be a starter relay(page 307) could be wired in such a way as to kill all of the power to the ignition switch/dash panel??

Dave, I'm not Rich of course but, the solenoid (starter relay) you are referring to is part of the isolation circuitry that isolates the house batteries from the chassis batteries while the coach is not running, to help assure that the house circuitry does not draw against the chassis batteries when the coach is not running, the relay just above the solenoid is what activates that solenoid for auxiliary start in case of failed chassis batteries. Not likely that it has anything to do with deactivating any chassis components unless it is overheating and causing a thermal circuit breaker to sense an overheat condition. If there is and probably is such a breaker in the chassis wiring. A bad cell in a house battery could show up as a problem in this circuit. But as Bill pointed out, bad grounds can be a culprit, and the house battery bank ground system as well as all grounds in the chassis wiring would be my first check points. I also noticed that that the solenoid is a two wire solenoid, is there a ground wire attached there when the board is installed? If it is not there it should be otherwise the solenoid cannot function as intended. While looking at the picture I overlooked your reference to page 307, all of the above is in reference to your picture, sorry for overlooking this.

[hermanmullins]

Is it possible that the fuel valve is shutting off when it gets too hot?

Herman

[fountaincharles2]

Herman, I don't know if a fault in the fuel system will kill power at the Dash Panel, etc., but if the ignition system goes dead the fuel system will certainly stop. Anyone have knowledge in protections built into the fuel cutoff?

[dickandlois]

Dave,

I put together some information on the electrical issue you are dealing with .

 Have been experiencing an error when trying to convert it to a PDF file. As soon as I figure out the  unlisted error code I will convert it.

Do you have Microsoft Word software loaded on your computer? The file is currently in that format.

There is some interesting items to check. I just hope  the file helps understand what might be happening.

Rich.

Note! sent a copy a link that will slow you to get a copy of the owners manual for your coach. But you have not accessed it yet. So I will attach a link here.

https://www.monacocoach.com/resources/media/manuals/2002_Diplomat.pdf

It is a large file and it might take sometime to download. 

Rich.

[dickandlois]

8 hours ago, hermanmullins said:

Is it possible that the fuel valve is shutting off when it gets too hot?

Herman

Herman, Loss of power to the ignition system and accessories could also be killing power to the fuel lift pump. There are about 38 circuits powered from the front fuse box and none of them are bad according to Dave. There is a manually operated switch in the circuit that is in question. Hope Dave gets back to me.

Rich. 

[fountaindavid.jean]

Rich, I have a copy of the Coach Manual that came with the Coach. Sorry I didn't mention it earlier, but I initially thought the Manual you were talking about was a Service Manual.  I don't have Word, but can get it.

With respect to the earlier question I had with respect to the Starter Solenoid, as I recall from a previous starting problem, when the starter solenoid wouldn't engage due to a loose wire, the dash panel did show lights as well as the tranny panel. That was several years ago. So, I may have answered my own question relative to the actual starter solenoid. My particular Coach may not be wired so as to kill all of the power if that solenoid were to cause a problem. Just trying to eliminate the Solenoid as a culprit.