Engine will not turn over except for jumping solenold

[calvin cockrell]

Have power when i turn key but starter wont turn wire from battery is good put new ignition relay in and ignition switch in but still nothing

[david craft]

It could be that the isolator youve found is a 3 post with an excitation circuit for a CS series delco alternator. If its a sure power it will have a blue dot on a post. Just ignore that post and use the other three. Did you ever try grounding the wire that goes to the start relay to the neutral switch?

[calvin cockrell]

I left all the wires on the isolator hanging still no start eccept jumping the silonid

[calvin cockrell]

I have looked around for a isolator the only ones i found have 4posts

[calvin cockrell]

Does anybody have a part number for the battery isolator in a 1978 dodge mh

[Russell E Johnson]

I hope Calvin lets us know what the shop finds out is the problem.  It may turn out to be one of those "Oh Duh" moments. :)

[Russell E Johnson]

What I don't understand is why with the battery isolator removed the engine cranks over and with it installed it does not.  It is not even remotely associated with the starting circuit yet it effects the cranking of the engine.  

David, I too am exasperated by this.  It is so baffling and frustrating.  I presume Calvin replaced the isolator since it had a broken post.  

I chased my tail around for several hours on our 87 Chevy Southwind not cranking and starting till I found a relay that Fleetwood must have installed in the starting circuit because I have never run across it in their other trucks I have worked on.  I replaced it out of desperation and that cured the problem.  The MH engine turned over and fired right up.

Matthew you are right about this being SUCH fun, with things like this, who needs amusement parks! LOL

[david craft]

Sorry if I sounded exasperated...I am. You can label all the leads of the isolator and then tie them all together with a 1/4" bolt and tapes it off, If you think that there is a chance that the diodes in the isolator are shorted to ground.

[david craft]

I never did get a response to the question earlier...where we were trying to sort out the 2 small wires to the start relay

[david craft]

Assuming were bypassing the isolator. The center post is the alternator in. Post #1 is the alternator out to the chassis battery. Post #2 is the alternator to the coach battery. So, just take the wire off the #1 post and put it on the center post with the alternator feed. This will not make the engine crank. Did we try grounding the start relay?

[Russell E Johnson]

Calvin, you said the engine started when you removed the battery isolator.  Did you leave the 4 wires not connected, hanging as it were?  

OK, just thinking aloud.  As Matthew stated, the started should not be running through the isolator, however when you removed the isolator you disconnected the alternator connection to the main battery.  If the alternator is bad, could it be pulling enough power to ground so the starter relay is not closing?  

Thoughts anyone?