I think I might have a bad isolation solenoid because my house batteries aren't charging with the engine running...I tested by measuring volts on house batteries with engine off (12.1) and then with engine running (12.1). I pulled this from behind the green circuit board in the fuse center under the driver side, front of coach...but now I'm not sure if it's the battery disconnect or the solenoid...As you can see in this next picture, there is a button on the board that says to push it and listen for a click to test the aux start (I'm assuming this is talking about the solenoid??) but when I push it, I don't hear anything. I don't see anything else in this compartment that looks like a solenoid...We are leaving on a long trip in a few days, so I need help quickly! Thanks in advance!

In your picture you can see 2 large nuts and two small nuts, there should be 12+v across the two large nuts if it is working if only 12+v on one lug it is not engaging. Also check the voltage on the small nuts one should have a 12 v input to the solenoid. You can always jumper the 2 large connection to use the MH for your trip until you get a new solenoid.

Gjac wrote:In your picture you can see 2 large nuts and two small nuts, there should be 12+v across the two large nuts if it is working if only 12+v on one lug it is not engaging. Also check the voltage on the small nuts one should have a 12 v input to the solenoid. You can always jumper the 2 large connection to use the MH for your trip until you get a new solenoid.Is this the right part to replace if my house batteries are NOT charging from the alternator and if I don't hear any click when I push the battery boost button on the dash of the coach?

Also, I've read you can get one from autozone...how do I know the right part number that is compatible?

Gjac wrote:In your picture you can see 2 large nuts and two small nuts, there should be 12+v across the two large nuts if it is working Unfortunate wording.You should see 12V ON both lugs if it is working. (Exactly the same voltage.)Seeing 12 V ACROSS the two lugs means something quite different.

Before you get anything new in parts, make sure your ground return is good. Connect from the negative on the house battery to the negative on the coach battery with a jumper cable and just make sure that part is OK. A loose negative will prevent anything from charging.With just the negatives connected, start the engine and then see what the voltage is at the house battery.

Battery disconnect or isolation solenoid? HELP!

27 Replies

Chris_Bryant
Explorer II
May 16, 2016
The solenoid in the picture is the disconnect solenoid and has little (nothing) to do with charging off the engine.
That bottom picture references a service manual- try to find it.
Moffittclan
Explorer
May 16, 2016
Artum Snowbird wrote:
Before you get anything new in parts, make sure your ground return is good. Connect from the negative on the house battery to the negative on the coach battery with a jumper cable and just make sure that part is OK. A loose negative will prevent anything from charging.

With just the negatives connected, start the engine and then see what the voltage is at the house battery.

They charge on gen and shore...so I think that side of things is good...
Artum_Snowbird
Explorer
May 16, 2016
Before you get anything new in parts, make sure your ground return is good. Connect from the negative on the house battery to the negative on the coach battery with a jumper cable and just make sure that part is OK. A loose negative will prevent anything from charging.

With just the negatives connected, start the engine and then see what the voltage is at the house battery.
Sam_Spade
Explorer
May 16, 2016
Gjac wrote:
In your picture you can see 2 large nuts and two small nuts, there should be 12+v across the two large nuts if it is working

Unfortunate wording.
You should see 12V ON both lugs if it is working. (Exactly the same voltage.)
Seeing 12 V ACROSS the two lugs means something quite different.
Moffittclan
Explorer
May 16, 2016
Also, I've read you can get one from autozone...how do I know the right part number that is compatible?
Moffittclan
Explorer
May 16, 2016
Gjac wrote:
In your picture you can see 2 large nuts and two small nuts, there should be 12+v across the two large nuts if it is working if only 12+v on one lug it is not engaging. Also check the voltage on the small nuts one should have a 12 v input to the solenoid. You can always jumper the 2 large connection to use the MH for your trip until you get a new solenoid.

Is this the right part to replace if my house batteries are NOT charging from the alternator and if I don't hear any click when I push the battery boost button on the dash of the coach?
Gjac
Explorer III
May 16, 2016
In your picture you can see 2 large nuts and two small nuts, there should be 12+v across the two large nuts if it is working if only 12+v on one lug it is not engaging. Also check the voltage on the small nuts one should have a 12 v input to the solenoid. You can always jumper the 2 large connection to use the MH for your trip until you get a new solenoid.

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Battery disconnect or isolation solenoid? HELP!

27 Replies

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