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Krash · 11-21-2014, 08:46 PM

I am new to this forum. A member on another forum suggested I post this question here. Glad I found this forum because I am sure to have lots of questions.

The cruise control on my (new to me) 2002 Monaco Diplomat does not work, and I am hoping that one of you good folks might shed some light on what the problem may be. Here is the information I can provide at this time.

Cummins ISC 330 hp engine with three switches for the cruise control.

SW1 - Cruise “ON/OFF” (this switch has a light on it when ON, and it is working)

SW2 - Cruise “CANCEL”

SW3 – Cruise “SET and RESUME”

Although the ON/OFF switch seems to be working, I cannot get the cruise control to engage.

I have read many posts which have indicated several problems, and so I have checked some of those. The brake lights are NOT on when trying to engage the cruise. (I had the DW follow me) And, the exhaust brake is NOT on, or engaged.

It is my understanding that the cruise control is a function of the Cummins ECM, but I was wondering if anyone can suggest other things I might check before taking it to Cummins? Like maybe a fuse or relay?

Thanks for the help!

DtBt · 11-21-2014, 09:34 PM

With the mention of a lighted switch I assume you do not have a VIP smart wheel but the Carling switches on the side console. You are correct that the cruise control is a function of the Cummins ECM and the switches go directly to the ECM. Have you checked the switch connectors and any intermediate connectors under side console panel. One of the switches could be bad as well. There are at least two brake light switches on the front firewall, one normally on and one normally off. Check that as well.

Krash · 11-21-2014, 09:55 PM

Thanks DtBt. You are correct, no smart wheel.

Checking the switches and connections was going to be my next step, but I thought someone might know of a fuse or something. The switches will be a little hard to get to, but I will sure be happy if I find one is bad.

Can you expand on the two brake light switches you mentioned? I have checked the brake lights and they are not on when testing the cruise control. I had my wife follow me for many miles, and the brake lights worked perfectly normal.

Gorlininc · 11-21-2014, 10:03 PM

I have a 2001 diplomat. I believe that your cruise control on/off switch gets power from a fuse like mine. I have the wiring diagram I can check tomorrow am. I've changed the switch a couple of years ago even though the on light worked on the switch. It's an internal connection.
I'll write you in the morning with the circuit that controls it
Rick

DtBt · 11-21-2014, 10:11 PM

I just checked the schematics for a similar model and saw a cruise cancel relay that my 99 Windsor did not have where they no longer use the normally closed brake light switch connection. My schematics show it there, just one side connected. I'm not sure where your relay would be but that might be something to look for.
I would definitely lift the console and inspect the connectors and test the switches. Also trace the wiring as I believe there is a big connector down there. I had mice in that area of my Windsor but fortunately they did not chew on any wiring.

Gorlininc · 11-22-2014, 10:36 AM

Ok looking at the wiring diagram. The cruise on/off switch is s double pole switch. One side connects to the ignition and the on light when the switch is turned on. The other side grounds the cruise control wire to the computer. Therefor the on light can light up when turned on and the other half of the switch could not be making the ground to turn on the cruise control.
I'd check the wiring if it never worked since you owned it. Otherwise I'd change the switch. They do go bad and I had to change a couple of them. They are pretty easy to change from underneath. That's where I would start.
Rick

Gorlininc · 11-22-2014, 10:39 AM

You may also want to check the cruise cancel switch. It's a normally closed momentary switch. If that circuit is open across that switch the cruise control will not activate.
Rick

Krash · 11-22-2014, 11:33 AM

OK, problem solved. No rodents, no troubleshooting, and no head scratching!

I opened up the side panel from inside the coach where there is a rats nest of wires. Just what I expected. The bundle of wires that were grouped together for the three cruise control switches were ty-wrapped. Also, seemed logical.

They were very tight because of the way they ty-wrapped. After cutting it to access the individual wires, the problem became obvious. The middle switch connector, "Cruise Cancel", had been pulled completely off the switch. I suspect this was because of the weight or tightness of the bundle.

Anyway, plugged it back in and everything worked as it should.

It goes to show you that sometimes the solution is just so simple, you are caught off guard.

Thanks to all who took the time to guide and advise me, and help me fix this problem.

Gorlininc · 11-22-2014, 11:36 AM

That was my option B. An open cancel cruise circuit.
Great. I'm happy it's fixed.
Safe travels.
Rick

Krash · 11-22-2014, 01:06 PM

Yep Rick, you hit the nail on the head on that one.

JMB111333 · 08-29-2022, 05:07 AM

I have been having the same problem with the cruise control on our 2004 Monaco Knight. I will have to check the wiring from underneath like you did. One problem I ran into was Cummins said the cruise is a Monaco problem, not a Cummins problem. I called REV and they could not help either.

jacwjames · 08-29-2022, 07:00 AM

This is a really old thread, you might consider starting your own.

But I read through the posts and problem was solved. On the left side of the drivers seat there is a console. The out side panel comes off. There are a series of 3 relays zipped tied together. The OP found a loose wire on one of the relays.

Need to find a wiring diagram. Check IRV2 files section

You might also consider joining the Monacoers.org site. This group has many senior members that can possible help. Check the downloads section for a wiring diagram.