Boost solenoid wiring help needed

JHL

New member
Help! I have a 2009 Winnebago View on a 08 Sprinter chassis. Recently I noticed that my chassis battery was draining quickly during storage. Through some troubleshooting with my meter, I discovered that I am getting voltage from the chassis battery to the boost solenoid even with the engine off so that the solenoid is always closed linking my house and chassis batteries. I recently replaced the Y cable, the chassis battery, the boost solenoid, and the boost switch. I traced the voltage back to wire KE2 at the boost switch. Any help would be greatly appreciated.
 

calbiker

Well-known member
You may have a mis-wire after replacing the solenoid and boost switch? I find it odd that the boost switch was replaced. That normally does not fail.

You need to take some voltage measurements. The solenoid may have 3 connections: two big cables and one smaller cable (the solenoid may have 2 smaller cables). Measure voltage from the smaller cable to chassis (you can put neg voltage probe on the body of the solenoid it's metal). There should be zero volts. If you see voltage then you probably have the boost switch mis-wired or it's kaput.

Edit, take the measurement with engine off. With engine running you should see 12V at the small cable to solenoid. Also, with engine off, and boost switch activated you should see 12V on small terminal.
 
Last edited:

JHL

New member
Thanks for your reply. I replaced the boost switch because I was grasping at straws. I tested the old one and it checked out OK too. You really cannot mis -wire the boost switch because it is attached to the wiring harness with pre-attached connectors that only go on one way.

With the engine off I get the following at the solenoid: small post with LR (yellow wire) to ground 12.3v, Large Post (Chassis side) to ground 12.3. Large Post (House side) to ground 12.3. Large post to large post 0. Small post to small post 12.3 (this is a four post Cole Hersee). Realizing that I should not have any voltage on the chassis side or the LR small post of the solenoid with the engine off, I disconnected the battery boost switch and found that I have 12.3v coming into the switch when I should have 0. Once again, I appreciate your input.
 

autostaretx

Erratic Member
If you have 12.3 volts across the small terminals of the Cole Hersee, that means the relay is being actively commanded to join the batteries.

Depending upon how the system is wired, i would expect to see one end of the Hersee "floating", so that zero volts would be seen between the two small terminals.

So whatever is driving the Hersee is what's at fault. The Hersee is just doin' what it's told.

--dick
 

JHL

New member
Thanks for your input Dick. I understand that the CH is just doing it's job. I am trying to figure out what is telling it to do that when its not supposed to. I even took the CH out of the equation by removing the wire from the small post and I got voltage at the wire's ring terminal. I then went further "upstream" and disconnected the boost switch and and I found 12.3v coming into it with the engine off. Something is providing voltage to the boost switch and then to CH all of the time instead of only when the engine is running.
 

calbiker

Well-known member
You're on the right track. Follow that wire! It's the D+ wire. There's a D+ relay which might be stuck in the on position. Or the relay coil is falsely being energized.
 

JHL

New member
Thanks Calbiker, I have traced the KE wire back to the D+ terminal under the drivers seat. That terminal is supposed to be energized only when the engine is running but it has voltage all of the time. I found the K88 relays on the drivers seat fuse box and they tested good. Pulling the #12 fuse cuts the power. Any other thoughts?

Thanks,
John
09 Winnebago View/08 Sprinter 3500
Jacksonville FL
 

Top Bottom