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Coach loses electreical and shuts down
On the highway sitting in traffic and all dashboard lights started flickering and buzzing (similar to test mode) then the engine shut down and I had nothing = no electical on the dash. turned key off then back on again nothing – no dash lights gauges, outside temp – Nothing. 10 minutes passed i heard clicking in the service door area then the dashboard lights and gauges started back up which enabled me to start the coach. 26 volts on the gauge and the bus ran for another 10-15 minutes then repeated the flashing and buzzing shuting down once again. This time we were slowing moving and the engine shut down again. 25 minutes later clicking again everything came back on the bus started allowing me to get into a safe area off the road, Idled for 20 minutes then shut down again this time for about an hour or so before started clicking.
The only active error message is Engine SID 214, value to low
I removed and tested R1 relay and it appears to be working fine.
Engine batteries are less then 2 months old – lights remain on the 12/24 volt box in the engine bay, battery monitor shows green for the 4 engine batteries but no power to the dash area. all circuit breakers are on. I tripped all and reset just to be sure as well.
The coach is a 2000 XLII-45 Le Mirage Entertainer with a Vulcan conversion (old senators coach) approx 615,000 miles with a detroit series 60 and 6 speed select allison transmission.
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9 Replies
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Only a stab in the dark but are the master switches back by the batteries fully engaged, and if so can you measure the resistance across the main coach circuit breakers. Is the power to the ignition relay steady and uninterrupted?
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Jon I don’t see any master switches. All cables from the 4 engine batteries go directly to the 200, 70, 30 amp push button resets and the jump posts as well as the 12/24 volt box. It appears I have full power in the engine area but lose it in the service area bay below the drivers seat. All relays are cool to the touch and all connections are secure. The only thing I haven’t been able to verify is power at the 12 volt and 24 volt master terminals on the bar near the fuse box in the service bay. Currently there is power on both sides of jus terminals but I also can currently start the bus. Roadside service techs are stumped and the closest Prevost service center is in NJ as I am currently stuck in MA and affraid to get on the highway and have the bus shut down traveling at 65+ mph
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Try starting from the rear on manual and see if it continues to run. Just a thought…
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Based on the description it sounds like you are having an intermittent open circuit. That is the worst possible problem because unless and until the circuit has failed you cannot find where it is open. And sometimes even if it fails the meter shows continuity because you can get enough current flow to read a value, but not enough to do the work.
The master switch(s) are either going to be a pair of shut off switches at the post where the main coach CBs are located (a big black handle and a smaller grey metal pointer type knob) or a small toggle switch which actuates a bigger relay behind the black plastic shroud. I’d start there looking at connections and contacts and follow the circuit.
I yield to Prevost if they have places to start looking. And you are correct. Taking the coach out on the northeastern highways without solving the problem is too dangerous because you not only become an obstacle with a stalled coach, you will even have a hard time steering it when it shuts down.
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I have seen this problem as well, Jon is right. In the rear engine compartment, there is a master disconnect solenoid, when that solenoid starts to go bad you will experience the same problem that you are having. A temporary solution may be to move both the input & Output cables on that solenoid to the same post to keep the circuit constantly completed. It will get you down the road anyway. Might be worth a shot for ya!
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so it happened again yesterday but this time I was able to do some testing before it came back on and what I found was there was 12 volts in the service bay but no 24 volts. Went back to the engine bay and I had 12 volts at the banner but no 24 volts. I had 24 volts at the last battery then there was a loud clank at a black box with two terminals and every went live again. I am going to guess this black box is the 24 volt selonoid you were referring to. I have been to many places and no one carries them or ever even heard of it. Could you please direct me in the right place to buy one. Thank you for your help.
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For temporary service, connect the terminals together to in effect bypass the relay as was suggested above.
The only downside to doing that is the master switch will be on 100% of the time, but you will not have any failures as you hve been having. Prevost should be able to overnight the relay to you.
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I did pick up a SAE J1127 SGT TYPE 2 60V & SAE J378 50V 4 GA battery cable I am thinking this should be capable of serving as a jumper wire. Any thoughts.
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Too hard to guess over the internet. But I presume you understand what is needed.
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