No Power To Ignition: 2002 Monaco Knight 36PBD

[WindsorE]

SITUATION: No ignition activity (not even a click). Gauges activate with key on, but only Allison panel "N" and dash ABS lights are lit. With key off and out of ignition switch (and even with the ignition switch wire bundle disconnected), the Allison panel "N" and dash ABS lights remain lit.

BACKGROUND: In for lift pump replacement due to bad gasket. Motorhome was starting and running okay, but now will not start. There seems to be a total lack of power to ignition system.

ANALYSIS:

• RV tech said it is most likely due to a bad "Monaco #4 Rear PDC" (aka Monaco #4) box (rear passenger side bay) and added that these are common failures due to bad soldering.
• The box was manufactured by St. Clair Technologies (p/n 100744), but Monaco tech support said these are unavailable (obsoleted in 2007).
• The Monaco #4 is a relay and fuse panel holding 10 fuses and 6 relays which seem to control ABS, exhaust brakes, and ignition. All relays check good. The box is closed by four brass rivets.
• Troubleshooting over the phone with Monaco tech support. The Allison "N" and dash ABS lights could be ignition switch issue - ruled out by disconnecting ignition switch wire bundle behind dash. Monaco then said issue most likely with Monaco #4 box, but denounced this as a common failure.
• When the box is disconnected, the Allison "N" and dash ABS lights are not lit.
• When the box is reconnected, the ABS LT relay engages with a click, and the Allison "N" and dash ABS lights are lit with or without the ignition switch wire bundle connected.

RECOMMENDATION:

1. Request additional troubleshooting steps from forum.
2. Open Monaco #4 to attempt further diagnostics (blindly without schematics).
3. Find replacement Monaco #4 from salvage and begin throwing parts at this problem.

I have Google, Bing, and Forum searched this issue to the point of madness finding no hits for Monaco #4 Rear PDC outside of the random and useless results related to BMWs. It seems that if this were such a common point of failure, there would be some hit somewhere.

Any assistance is graciously accepted!

[abyrd]

Looking at the picture that you provided, it look like there are several plug in relays on the board.

I would check each relay to determine that the relay coils are good and also make sure that check the relay contact resistance. I assume you have already checked all of the fuses.

Replacement relay should be available at most automotive parts stores.

Jim

[jleamont]

Windsore, welcome to the FMCA forum! Sorry to hear of your problem. check the electrical connection to the left of the fuel pump. I replaced my pump last year and I remember having difficulty locking the connection, it is a round metal connector that is a twist lock and you have to disconnect it to access the pump. Depending on your floor access it should be a simple check, also poke around back there and make sure they didn't damage any wiring. I am assuming your coach is Cummins powered.

[hermanmullins]

WindsorE,

Welcome to the Forum. Have your tech check for a bad solenoid in your front bay.

Herman

[tcolburn]

I googled " Bussmann 31114" and "Monaco 16615338" and found a number of sources for another unit, should you need one.

--Tim C.

Park Forest, IL

[WindsorE]

UPDATE: Monaco provided the wiring diagram for the chassis and the Monaco #4 box which has nothing internal except the circuit board connecting the six relays and about a dozen plus fuses. I was able to test each circuit for proper continuity and resistance, and I could not find any problem with the Monaco #4 box. With great skepticism, the shop allowed me to go in and evaluate the connectors coming into the box. There are two connections for 12-volt power. One connection provides 12+ on both leads. The other connector is to provide 12+ on one lead and 12- on the other. Within two minutes, I determined that the second connector had 12+ coming to the 12- lead. I bypassed the second connector, and the coach fired up to the astonishment of everyone in the shop. I was going to leave the 12+/12- issue to the shop but remembered the advisor mentioned the technician disconnected the battery to remove the starter (???). I examined the battery bay and found a wire that looked like the wire going through the bay wall to feed the Monaco #4 box. Indeed, it was the 12- lead connected to the 12+ of the batteries. Another couple of minutes, and the problem was resolved. I did need to replace a blown fuse for the ignition in the front left bay. Wow, they could have really fried the electronics on this coach. The did reimburse me for the 4 hours of labor they had spent diagnosing the no start issue. I should have asked them to reimburse me for the lost time, fuel driving back and forth a few times (3 hours round trip), and my general frustration. I am just glad to have it running and out of their hands.

I do appreciate fellow forum members who provided advice. Moreover, I cannot tell you how appreciative I am that the Monaco techs spent about two hours (combined) talking with me and emailing me the specs on a 14 year old coach. That is amazing customer service IMO!

[abyrd]

Gland you found the problem and that the fix was simple.

One think that my fathers passed on to be was is you have a problem, go back and look at the last thing that you did before the problem surfaces. It's amazing how many time he been correct.

Jim

[jleamont]

WOW, nice job!

That shop should be embarrassed!

[wildebill308]

Glad you got it fixed.

Bill