Auxillary Start/battery solenoid

[Biggyniner]

Hi All..

I think I know the answer but I'm open to feedback/suggestions...

So I was doing some testing to my Minnie and come to find out the engine is not charging my house batteries. If I depress the AUX start button I hear an audible click, so I believe the relay works in that regard. I tested the house battery solenoid with the engine running and I do have ~14.5 volts on the chassis side of the solenoid and then just 12.8ish volts on the house side - the same amount that was there with the engine off. The generator/shore power will charge the house battery.

Before I swap the solenoid out is there anything else I should check? I hear there should/could be a fuse somewhere for this solenoid, would it be in the chassis fuse panel?

Thanks

[Harvey51]

Just curious - on engines that only pass current to the house when the engine battery is fully charged, how does the engine tell when the battery is fully charged? This technology would be great for measuring the state of charge of the house batteries.

Our 2004 E350 uses the built in Ford relay in the fuse box to connect the "auxiliary" line to engine power whenever the engine is running.

[enblethen]

Location of the relays vary by manufacturer and year. The OP has located the relay in question and needs to check it out for voltage to coil.

[4x4van]

On my '88 Jamboree, there are separate solenoids for the emergency start and the charge, both located under the hood. The emergency start solenoid is located on the firewall right next to the brake booster and has large battery cables, but the charge solenoid is mounted behind the driver side headlight. It has smaller (#8AWG?) wires. As soon as I turn the ignition on, the charge solenoid is energized and connects the house batteries to the chassis alternator to charge both chassis and house.

[tenbear]

The only way you can be sure the solenoid is energized is to measure the voltage on the small terminal(s). It really doesn't matter if the energizing coil is open or if the contacts are worn out. If you don't have continuity between the 2 large terminals when there is 12v applied to the small terminal(s) - the solenoid is bad. If you don't have 12v on the small terminal(s), you have a different problem.

[enblethen]

You can also have a helper operate the system, and feel for the relay to energize.

Three post relay

Installation/information

[Biggyniner]

enblethen wrote:
Does the relay with 14 volts on one side and 12.8 on other, have 12 colts across small terminals or single terminal to ground?

I have not tested the small 'hot' terminal, I was going to do that next.. It only has the one small 'hot' terminal, the ground goes to the body mounting screw of the solenoid.

[enblethen]

Does the relay with 14 volts on one side and 12.8 on other, have 12 colts across small terminals or single terminal to ground?

[Biggyniner]

JaxDad wrote:

Beverley&Ken wrote:
I believe that there are 2 different relays/solenoids. One for the boost feature that connects the house batteries to the chassis battery and a second that allows the house batteries to be charged from the chassis

ken

X2

There is one relay in the engine compartment (the charge controller) and one in the battery bay (the aux. start relay).

I believe you will find the one under the hood is shot. It's a relatively easy swap despite the cramped quarters.

Are you sure it is the one under the hood? I was inclined to believe it was the solenoid in Aux battery bay because I am getting 14 volts to one side of it, but 12.8 on the other (house) side of the solenoid.

[fourthclassC]

Howdy,

Went through this recently 2003 Winnie Mini. The isolation solenoid clicked real goo when I checked it with a battery. BUT no continuity change. Very common failure mode. electromagnet ok but contacts worn out / failed. Get a continuous duty Napa solenoid. Beware, if it is located in the same place as mine was, it is very difficult to disconnect/replace

[JaxDad]

Beverley&Ken wrote:
I believe that there are 2 different relays/solenoids. One for the boost feature that connects the house batteries to the chassis battery and a second that allows the house batteries to be charged from the chassis

ken

X2

There is one relay in the engine compartment (the charge controller) and one in the battery bay (the aux. start relay).

I believe you will find the one under the hood is shot. It's a relatively easy swap despite the cramped quarters.

[F1bNorm]

Sounds familiar, check this thread:
Clicky

Norm

[Crem]

About 5 years ago I had the same problem on my 2003 Itasca. I removed the solenoid and using my grinder I ground around the edge of the top cap on the solenoid so that I could remove the top. I was then able to clean up the inside contacts and tack weld the cap back on again.

[tenbear]

The solenoid in my rig is energized when the ignition is on. There is also a circuit breaker in series with the solenoid contacts. Since you are not getting the same voltage on both sides of the solenoid when it is energized, the solenoid is not making contact, the circuit breaker or fuse is not in the picture.

[enblethen]

On my rig, when the chassis reaches a set value, the charge relay energizes. The charge relay and the aux start is the same relay on my rig.
It has a separate ignition relay that energizes to provide power to coach manufacturer installed items.