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Cranked With The Key But Started Only From Back
I had another glitch today that may or may not be related to my recent problems.
When the bus shut down Thursday 110 miles east of Houston, it started right back up after we got stopped. The first and second time it started and died I had started it from inside. The third time that I started it, I flipped the switch by the engine and then started it from the back. My wife turned the key on inside and we let it run about 20 minutes. Jeff told me to flip the switch to normal in the back and it should keep right on running. It did run and it ran until we shut down over 5 hours later.
Friday, start inside, run 395 miles, no problems.
Saturday we started fine and drove about 40 miles, parked in a lot and walked to lunch. After about an hour I turned the key and it cranked, but did not start. The second time, it cranked, but did not start. I walked to the back to look things over and on a whim, I reached up and flipped the switch to rear start and pushed the button. It instantly roared to life. I turned the key on up front, flipped the rear switch to normal and finished my short drive for the day.
When we arrived and leveled, my wife shut it down. For kicks and grins, I asked her to start it again. It fired up like normal.
What in the world? Ignition problem? Ground problem? Loose wire? Is there a problem with the switch in the back? Could there be something related to the engine coming out and going back in? Is this related to the shutdown and crank right back up two days ago? What do I check?
Davy
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40 Replies
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Davy,
Those rear switches are prone to problems, replace it and you may be good to go. It could also be a combination of the key switch and the rear start.
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I recall reading discussions about the failure of the rear switches. What do they normally do when they fail? Can someone walk me through the diagnostic process?
I would like to get to the bottom of this without involving more heart attacks or tow trucks.
Davy
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The rear switch has an off, front and rear position. If the terminals when the switch is in the front start position are corroded it generally will not let the coach start.
But I never heard of the switch allowing the engine to spin, but not start.
You might have something else going on Davy.
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Thank you for the information, Jon. That helps me. Does anyone have an idea what I might need to check or suspect?
Davy
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You have to be careful with my “advice” Davy. Parse the words. I did not say it is not the switch but I did say I never heard anyone that had a switch problem said it would crank but not start.
If it is the switch sometimes cycling it through the 3 positions will temporarily get things working as they should. But if current is flowing through the switch so the starter should engage I am uncomfortable with the assumption the switch is why the engine won’t fire. Assuming you have fuel to the injectors there might be another reason it will not start.
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I understand, Jon. Point taken.
I also understand that the bus not starting on two tries with the key and then starting as soon as my finger hit the button in the back may have no correlation at all either. On again, off again problems are a bear, but I sure am glad it started and brought me the final 25 miles or so.
I post these glitches here hoping that someone has seen exactly this an can say with some degree of certainty, “Check the…”
Davy
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I am finding nothing loose, burnt or corroded in the box above the engine. It was hanging down quite a bit more. It was loose before the engine came out, but now so loose that I could not swing the door open without lifting it up. I put some screws in it to pull it back up tight.
These are the connections on the rear start switches.
Does anyone know what these five relays are for? They are not listed on the Prevost sticker on the door at all. Four of them have labels that say Stop, Left, Right and Converter Bypass???.
I have not started the bus since I first posted this, but we have about 80 miles to drive Saturday. I am hoping for no more glitches, but keeping my eyes open.
Davy
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Davy,
Maybe I am reading it wrong, but I got the sense you said the entire rear electric box has fallen down, or perhaps is so loose it is dropping.
If that is the case do not drive the coach unless you can secure it back into its original position. A few years back several of us had rear electrical boxes come loose and drop down onto the engine. Apart from the obvious problem of having a loose electrical box sitting on a running engine, the issue was really worse because on the bottom of the boxes are three electrical posts for 12, 24 and ground connections. I can only imagine the excitement available if those electrical terminals start to short out on top of the engine.
Definitely make sure the box is secured in its original position. The problem is the rivets used to secure the box when the coach was manufactured are aluminum and they corrode and fail. All owners of coaches should be making sure the rear electric boxes are secure.
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Your understanding was at least partially correct, Jon. My description left room for misinterpretation. The box was loose at the top and leaning. It was not completely fallen. It is secure now. Thank you.
Davy
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Whew………that’s good news. A shower of sparks from electrical posts sitting on top of your valve cover is never a good thing.
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Sounds like those relays are for trailer lights.
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I cranked and ran the bus 80 miles today and it did fine. The drive was one hour and forty five minutes and the total run time was about two hours and thirty minutes. My moves the next two weekends will be relatively short again. I am hoping this is behind me, but not super confident. I am open to any ideas.
I did finally get the bus washed. The back had a few thousand miles of road grime and all the greasy finger and palm prints from the repair. It was a mess. I never put soap on the sides, except for the tires and wheels and maybe one other time on the back. This one required soap and scrubbing.
Better
Davy
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I will keep this new development under this thread because until I learn differently, every electrical problem I come across is related.
I got out of bed this morning, walked to the front of the bus and noticed an idiot light illuminated on the dash. What in the world? It is the check engine light. The key is not on, but the light is on. It might be slightly dimmer than normal, but it is most definitely on.
I turned the key on and then off again. After the key is off, an alarm sounds 16 times in rapid fire. At some point during that alarm, the check engine light and the shutdown light comes on. Then the shutdown light goes off and the check engine light remains on. All other dash lights go off when the key goes off as they should. It did the same thing three times. I did not try to crank.
What is going on?
Edit: More Information: What I perceived to be engine lights that were slightly dimmer caused me to check the battery voltage. The voltmeter on the jump lugs read 16 volts. I plugged up my charger and turned on the breaker. Monday I checked those lugs to make sure my meter was reading correctly and they read 25 volts.
I went inside and checked the Detroit Diesel Monitor just now and it reads an error as Check Engine Battery Voltage Low Engine Hours 7669 (Which is now) and Duration 2:13:55. Check engine light is no longer illuminated.
Now, these batteries are NAPA and 4.5 years old. Before you immediately say replace the batteries, think this over. They have performed flawlessly through this whole break down. The bus was cranked a lot trying to get it running before the harness was replaced. One of the Mid Coast guys cranked so long I feared for my starter. The cranking batteries did not slow down one ounce through it all. Also, I was parked last week from Saturday to Saturday and the batteries were fine.
Could be many things, but three immediately come to mind.
One, I have an electrical problem from recent work that is causing other problems and something is running down the batteries.
Two, this is something totally unrelated. I have checked all the lights including the lights in the engine compartment that I had turned on for the picture I posted in a different thread yesterday.
Three, so much was asked of these batteries the last few weeks and it has worn aging batteries down.
I need some help.
Second Edit: The Detroit Diesel Monitor is staying on, not going dark as it always does after a minute or so.
Davy
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Grimlins for sure. Those 4.5 year old batteries would be the first thing I changed. That’s old for batteries even if they have been cranking good. Have you disconnected one battery terminal and put a volt meter inline to check draw with master switches on and off, just sitting with nothing on? Never know might have a phantom draw. Do know with mine when I had a dead cell on one it caused all kinds of problems. My start batteries are 2.5 years old and fixing to change them out just to be on the safe side.
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You may be right on, Glens, and I am definitely willing to consider it.
I need someone to think outside the box IF necessary. Is there something else that could be causing all of these problems? Something particular that is loose? Something not connected well? A malfunctioning relay?
Davy
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