Isolator wiring - is a third rear solenoid standard by chance?

June 12, 2017, 12:37:10 pm

This question which is way more difficult to ask correctly/explain. Hopefully this makes some sense!

Background - I am replacing the present isolator with a Sterling alt/battery charger isolator. I have hit a wiring snag.

My present isolator is a 3 post - not 4 as shown in the diagram.

I have the 2 solenoids as pictured plus a third one not shown on the schematic that is mounted on the back of the isolator board. Is this normal? If so would any one know its purpose? This is what I know about it: Its excite wire comes off of the boost solenoid. One power lead of the rogue sol goes to a neg post on a house battery. The other power leg [wire X] goes to the starter - somehow!. Here is the deal. When I test wire X w/my power-probe the wire shows chassis ground. But when I remove the positive cable from the cranking battery wire X no longer shows ground. Maybe its hot w/the motor running? Not sure and I have lots disconnected presently so am hesitant to start the DD. I did disconnect it earlier and motor ran, alt was charging fine. Removing the negative from the crank battery has no effect. Ignition key on/off no effect. When the boost switch on dash is switched on the light on the switch does not illuminate. Other info - the house batteries and crank batteries were jumped together making for one large bank. Maybe this 3rd sol was an abandoned attempt at another boost sol? Regardless should I eliminate the 3rd sol - if so what to do with Wire X or should I keep the 3rd sol? Finally I have not climbed underneath the coach to look at the starter; I was first hoping for an obvious answer before I went that route. Thank you

-Nick

Re: Isolator wiring - is a third rear solenoid standard by chance?

Reply #1 – June 12, 2017, 08:07:39 pm

It is probably your start solenoid from the ignition.

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