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Old 10-16-2019
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RVinCT RVinCT is offline
Senior Member
Join Date: Jan 2018
Location: Rockfall
Posts: 400

I thought this problem was resolved, and perhaps it was, but ........

We'd been camping for 2 months in the same area until the Maine campgrounds closed for the season, so they kicked us out. We headed south and got about 15 miles out when the engine completely died. All lights on the dash were out. The RoadRunner4 had no power, no gauges, no speedometer, nothing in the front had any power except the transmission lights. The engine shut down and we coasted to a stop at the side of the road.

The engine would crank, but not start.

Bertie was so tilted we couldn't run the fridge. A few phone calls confirmed that Cummins couldn't help and the nearest place that could work on the engine was in Bangor, Maine. A tow there would cost about $3,000!

Eventually, we found a local who worked on Cummins and could at least provide some roadside assistance to look for the problem. After putting out the emergency road reflectors, I got out the schematics and started to check things. The fuses all were good. I decided to start at the engine batteries and work forward.

The engine batteries were good, and the engine battery disconnect was sending power through. Then I remembered from the schematics that the engine battery disconnect was double pole single throw. One pole (12v high power) disconnected the starter/alternator. The other pole (12v low power) handled other engine and dashboard power. It was reading 4.0 v DC on one side and 13v on the other side.

That wasn't right! With the disconnect switch closed the voltage should be the same on both sides of the switch. I grabbed a jumper wire and connected across that pole of the disconnect switch. The dash lights and gauges all came back!

That part of the switch is fused at 80A so my jumper wire was too small. I removed the cable from the bad outgoing side and connected it to the incoming power side to bypass that part of the switch.

The roadside repairman showed up then

The engine started and ran great. We're now at our next campsite after 4 hours of trouble free engine operation.

It's possible that the engine shutdown and power related issues we experienced in this thread were caused by that engine battery disconnect switch failing intermittently. ???

If your engine dies and your gauges lose power, but the starter still works, check the 80A side of the engine battery disconnect switch. Mine can't have been operated more than a hundred times or so in its entire life. It looks to be in perfect condition, but obviously, that's no guide.

I hope this will help someone else.
Todd and Karen Pattist
Rockfall, CT
2007 Double Slide M380 "Bertie"
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