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Technical Support / Re: Engine Shutdown While Driving

« Last post by Bill Heffernan on Today at 02:09:52 AM »

More - rough start to yesterday. It shutdown probably 15 times before it started and ran for 30 minutes without issue. We ran it to Freightliner in Olympia. They finally got to it this afternoon. They found that the volts were dropping to the ignition relay. They are messing around on the repair and likely can't touch it until next week sometime. I'm going to jumper it to get it out of there. I'm not at the coach currently. A search indicates that the relay is an AC Delco F1757. Can anyone confirm? Thanks

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Technical Support / Re: Engine Shutdown While Driving

« Last post by Scott Shearer on October 02, 2026, 09:38:37 PM »

Dan,

The engine-shutdown issue discussed in this thread—unexpected shutdown and/or cranking without starting—is specific to 2006 and newer Monaco-built Patriot, Patriot Thunder, and Marquis coaches equipped with Intellitec circuit board-based front and rear run boxes.

Your coach uses engine run/start circuitry that differs significantly from the Intellitec system. However, it can experience similar run/start issues, including problems with the remote-start function.

Several BAC threads address these issues for your coach’s model and year and include recommendations for fixes and spare parts.

-Scott

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Technical Support / Re: Engine Shutdown While Driving

« Last post by Allen Heath on October 02, 2026, 05:28:37 PM »

It's an '07 Patriot Thunder 45' Winchester III.  Probably close to the OP's coach.  C-13, build date 09/06
Full function Aladdin, Medallion cluster, etc

I just figured out how to add that to my signature.

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Technical Support / Re: Engine Shutdown While Driving

« Last post by Dan Johnson on October 02, 2026, 02:01:54 PM »

Allen   What year of beaver do you have? Are the engine stopping issues the Monaco version or the beaver make version?

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Technical Support / Re: Engine Shutdown While Driving

« Last post by Allen Heath on October 02, 2026, 03:26:52 AM »

I had the annoying loss of power and engine turning off for about a year and a half. Shops could not find the intermittent problem.  Then one time while I coasted to a stop on the road I immediately went to rear run box and all the LEDs were off.  I thumped the relays and the "weak" one came back to life and the RRB lit up like the Christmas tree it should be.  So, I had now identified that illusive relay, and as I was in Newfoundland at the time I picked up a common Bosch pigtail and relay and soldered it in parallel to that relay.  Worked for 3 months until I got back home and did a proper replacement solder job.  I would highly suspect the same relay Fred and I had experienced.  When the contacts break connection the ECM just thinks you turned the key off so the engine stops while all the gauges report a comm failure as they are still powered on but the ECM isn't talking to them. Sometimes a bump in the road would shake that relay enough to re-make contact or sometimes break contact.  Turning the key Off and back On would most of the time have the contacts close firm enough to work again for a while.

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Technical Support / Re: Engine Shutdown While Driving

« Last post by Bill Heffernan on October 01, 2026, 02:49:00 PM »

Thanks Scott. We are moving again later today, I'll be watching for it.

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Technical Support / Re: Engine Shutdown While Driving

« Last post by Scott Shearer on October 01, 2026, 10:01:00 AM »

Bill,

Seeing zero boost would be expected, the engine sensors have lost power because the 12-volt switched ignition power to the engine ECM has been lost (loss of engine comm).

Our 2006 PT does not have the Medallion Digital instrument panel or the Light Bar like your coach, but I am running the Silverleaf VMSpc. Both the Medallion Digital system and the Silverleaf receive their information from the same source, so it should be a reasonable comparison.

When our engine shutdown the speedometer, tachometer and transmission gear attained were all registering data. I could see the transmission shifting down until I selected neutral. I did see the oil pressure light turn red and the oil pressure gauge go to zero (a bit alarming).
 
Suggestion, when you go back on the road run with your Aladdin system engine/transmission data screen displayed. If all engine data goes to zeroes during a shutdown, you’ll know that the 12-volt switch ignition power has been lost, the Aladdin system requires it to display any engine data.

-Scott

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Technical Support / Re: Engine Shutdown While Driving

« Last post by Bill Heffernan on October 01, 2026, 03:44:56 AM »

Thank you everyone for the recommendations and insights. The mechanic went through most of the recommendations, he found a number of corroded connections, including grounds, which he cleaned up. After a bunch of starts and stops (shutdowns)(pun intended) he finally got it to run for an hour with no issues. Of note, the dash would show a lost engine comm message after every shutdown, but when he pulled codes, it would disappear. We got back on the road and within miles we had another loss of power event. I was a bit more observant this time. We lost power, turbo boost went to 0, but the engine RPMs stayed up (I had not observed this previously.) This occurred about 3 times within 3 miles, each time within around 10 seconds we re-gained power and turbo boost. After those three "burps" everything ran great for the remaining 2 hours of our trip. These incidents felt very similar to what I have felt previously when this started, sometimes recovering like today, other times shutting down. In the repair yard it would simply shutdown without warning. Also of note, for the last three segments of our trip where we've had this issue, it seems to happen within the first 20-25 minutes of the trip and then runs fine. The mystery continues. 

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Technical Support / Re: Engine Shutdown While Driving

« Last post by Scott Shearer on September 30, 2026, 04:23:28 PM »

Fred,

Thank you for sharing the YouTube reference. The video was informative.

Watching the video, one might think it necessary to remove the rear start PCB prior to the installing the jumper wire, it is not. As an alternative way to shut down the engine while using a jumper is to turn off the chassis battery disconnect, then remove the fuse.

Very important!!
Jumpering the start solenoid as shown in the video bypasses all safety interlocks, including the neutral-start safety. Before proceeding, verify that the transmission is in neutral. Chocking the wheels is also recommended.

-Scott

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Technical Support / Re: Engine Shutdown While Driving

« Last post by Fred Cook on September 29, 2026, 01:26:35 PM »

Thanks Fred. Yes, we were able to re-start. We found a local mechanic. He went through all the electronics and did not find any issues. He pulled and checked fuel filters - one of them looked a bit rough he said, replaced them and checked fuel pressure, again no problems. After that it ran fine for about 20 miles, when we lost power briefly, but it did not shutdown. We kept going for anther 150 miles with no issues. At this stage it appears that it was a fuel/fuel filter issue. We are back on the road tomorrow. Hopefully no more issues.

Bill, from what you are describing I had the same exact problem…. Motor dying sporadically while at idle and while driving down the road. And… after dying it would restart when turning the key on again. Your problem is in the rear run box on your ignition board. Your likely culprit is the relay on that board which cost about $10 off Amazon. That relay is soldered on to the board. I pulled my board off and took it to a circuit board repair shop near my home. They cleaned the board up and soldered the new relay on. It’s been about a year and haven’t had a problem since…. Knock on wood. In the meantime there is a temporary fix as Scot described above to stay on the road. Get on YouTube and search Cummins ISL 400 ENGINE COMM ERROR. Although that guy has a Cummins, the run board is similar to a CAT.