My coach wouldn't start (sometimes) with solution - Printable Version
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My coach wouldn't start (sometimes) with solution - bikestuff - 01-29-2021
Gurus,
This may be a long post so here is the short version for folks with limited attention spans: 2000ish vintage coaches use a series of relays along with automatic reset DC circuit breakers to control the ignition and starting. A high current short not related to the ignition can cause breakers to trip which can shut down the engine....sometimes while driving the coach! The breakers did their job in protecting the wire...but the side effects were weird and not obvious. Read on to hear the story along with a few thoughts and lessons learned.
There is an old guru adage: When you hear hoof beats behind you...you should think horses instead of zebras. In other words before you jump to a complex cause to the issue you are having you should rule out the simple / obvious causes first. In my case...not only was it NOT HORSES....It was not even plain zebras...in fact what ended up causing my issue was multicolored unicorn zebras!
Here is the setup.... I have had (every once in a while) a problem where I would turn the key and nothing would happen. No lights on the dash, no cranking noise....nothing. A few more tries and the coach would eventually act like nothing happened and the coach would start. A guru friend helped me find and fix a loose wire going to one of the relays under the passenger kick panel a month ago or so. Coach started and the problem was solved! In the words of Coach Corso......Not so fast!
The issue came back with a vengeance. I was driving along and had been on the road for about 3 hours on a warm day. At a stoplight...the coach died. Turn the key....nothing happens. Oh great I thought. I turned on the flashers and got ready to start troubleshooting. I had beens stopped for maybe 30 seconds when I tried to crank the coach. It worked! Off I go.
Five minutes down the road, the coach died again. This time while I was at speed. I dove for the shoulder which turned out to be flat and clear. I turned on the flashers and started troubleshooting. I found the wire that my guru friend had helped me with had come unsoldered. Hmmmm. No worries! I simply replaced the spade connector going to the cube relay with a fresh spade connector. Reinstalled the cube relay and off we went. Or so I thought.
Five minutes later, the coach died again while driving. I again found the shoulder and started troubleshooting. I found that the relay that I had been fooling with the wiring on was rather warm. Hmmmmm. My guess is that the loose wire had caused heat to build up which failed the relay. No problem I thought....I will simply replace the relay. That got me going again. I said to myself....OK....THAT SHOULD DO IT. IM FINALLY FIXED.
I got the RV park I was going to only to have the coach die again while I was putting the slides out. Arghhhhh.
This time the coach really did not want to start. I even tried to use the starter switch in the back near the engine. That did not work either.
About this time a guru who shall remain unnamed, called me to offer his support and extended a generous offer to buy the coach for a heavily discounted price. I was so frustrated that I almost took the offer on the spot. But like my dad always told me....never make important decision in the heat of the moment. I told him I would think about it and let him know.
If you are still reading...let me summarize. The coach will sometimes not start and other times will die while you are driving along. The engine runs smooth and strong when it works and when it doesn't it is just like you turned the key off.
I called Newell support and an electrician got on the phone. He suspected that I was having an over-current situation and that breakers were opening up. He turned out to be right. He asked if I had a clamp on DC ammeter. (I did).
He then told me to go back to the terminal block at the engine and we found high current on terminal 4. There were 4 orange wires tied down and we used the ammeter to figure out which one was drawing current. When I removed that wire, the coach cranked like there had never been an issue. It was quitting time, so I told the Newell tech that I could figure out what the wire went to.
So what do I mean by "breakers"? It turns out that this vintage of newell uses a boat-load of resettable breakers similar to this:
Have you figured it out yet? What was causing the problem?
In another post, I found where my hydraulic fan control solenoid had failed and gotten melty. This caused a dead short. whenever the fan was called on to operate. This is why I could drive five minutes and then suddenly the engine died. It turns out that somehow the fan was powered through the ignition circuit. In other words, the fan has power whenever the engine is on. (It is controlled by an elaborate set of relays in the bay next to the engine). When the fan was supposed to come on...the ignition breaker saw enough current for it to open up which is why the coach died as if I had turned off the key. Update: A guru friend (also a real Electrical Engineer) pointed out that the voltage to the solenoid is removed when the fan is supposed to run so this part is probably not correct. What IS true is that the fan circuit was drawing waaay more current that it was supposed to. It occurs to me that there could be some sort of time-lag or maybe even a faulty breaker that only works when it wants to. Either way, the coach has driven about 12 hours without a repeat of the issue.
Replacing the solenoid and the associated valve along with the melty wires seems to have fixed the issue.
Lessons learned:
1). A clamp on DC ammeter is your friend. I would never have found the solution without one.
2). Breakers can trip with NO EXTERNAL INDICATION. If you find an electrical problem that comes and goes...you might want to check the breakers. Often times a breaker will feel warm to the touch if it has failed. In my case I found where breakers had voltage on one post but not the other....this is a sure giveaway that the breaker had tripped. Remember that the breaker will reset if you remove the current....this made me think I was going crazy.
3). The little Bosch cube relays that Newell uses come in different flavors with 4 or 5 pins. The pins can be in the right location but have the wrong function. Double check the little numbers on the pin side and make sure they are the same. Also, these relays have a maximum current rating. The auto reset breakers may or may not open in time to save a relay from damage. Keep extra relays in your spare cabinet.
4). Keep an eye out for loose and melty connectors and wires. I think that my issue goes back months and I fault myself for not noticing the wires going to the fan controller were getting hot.
5). Remember that when you hear hooves behind you...think horses....except when they are multicolored unicorn zebras.
RE: My coach wouldn't start (sometimes) with solution - encantotom - 01-29-2021
very nice writeup bill,
and the offer still stands if you break down again
tom