Troubleshooting the battery mode solenoid

[Dalsn1]

2003 Gas powered MH

My chassis battery was in the process of dying at 6 years old. When I tried the battery boost switch I got no boost, the house batteries were fully charged. After I got home I pulled up the wiring drawing and found the solenoid under the steps. I had my wife hit the boost switch and the battery mode solenoid clicked, but no boost. I read on another forum that to test this solenoid, start the engine and go to the one place panel and check the voltage. Both the chassis and house batteries should be charging with the engine running. If the house batteries are not being charged then the solenoid is bad.
Does that sound correct???
Thanks

Steve

[gaugeguy]

With both scenarios, my estimation is that the solenoid is the most likely culprit.

[Clay L]

The solenoid that connects the chassis battery to the house batteries is activated in two ways.
1) By a wire connected to the run terminal on the ignition switch.
2) By the momentary AUX Start switch on the dash.

With engine running you should measure about 14.5 volts or so on both sets of batteries. If it does click when the engine is started or when the AUX Start switch is pressed but the same voltage does not appear on both sets of batteries then it's a pretty sure bet the solenoid is bad.

[krautkamper]

If the solenoid is actually clicking, another probability is a bad or corroded connection on the heavy gauge wire in or out of the solenoid. Take a volt meter and check the voltage on each end of the cables before you go through the work and expense of replacing the solenoid.

[garym114]

The solenoid energizes and pushes up a copper bar that makes the connection between the two batteries. Over time the bar and the connection points in the solenoid get burned and pitted from connecting and disconnecting under load. The greater the voltage difference between the two batteries the more the bar burns and pits, until there is not a good connection between the two. This is the mode of solenoid failure.
With the solenoid energized the voltage should be the same on each large cable end.

[royinflorida]

A way to test the connections is to use a regular automotive type jumper cable to connect the large terminals on bith sides of the contactor. If that makes the voltage on both sides the same then the contactor itself is bad and must be replaced. Don't try to fix it it isn't worth the trouble.

Be carefull with the jumper cable do not let it touch ground.

Roy

[Dalsn1]

Replaced the solenoid and everythig now works properly. On to the next item on the punch list.

Steve