What is this switch for?

jlrray · 05-21-2008, 04:42 PM

There is a switch by my left knee on the drivers side that i have no idea what it does. Its a momentary switch that causes a solenoid to click up under the hood near the front / drivers side area.

The black one on the top allows manual illumination of the rear aux lights. What does the other one do? The front hella lights aren't even connected

Joe

armlock · 05-21-2008, 05:03 PM

Could it be a valet switch for your alarm?

jage · 05-21-2008, 11:11 PM

Weird though the valet switch should be hidden. The high idle switch is around there on the diesels, but there is no solenoid and it's a lighted OFF ON switch.

Put the parking brake in with the van idling in park and flip it see what it does.

Otherwise have someone flip it while you hunt the solenoid.

You could always call SMB.

Greg In Austin · 05-22-2008, 09:16 AM

I thought the switch in that location would be the high idle switch, but it turned out to be the Air Compressor. We did not get a high idle switch as far as I can tell.

jage · 05-22-2008, 10:37 AM

It could be an override switch to the isolator or separator, the separator would click like a solenoid (and in later years they keyed the forced close off of a hot-on-start wire). Check your voltage at the front 9v and hit the switch- if it jumps that might be it.

John Kalmbach · 05-22-2008, 11:23 PM

Joe,

Jage is right on target with the switch. Prior to the Battery Separator's being installed, SMB would install a solenoid to connect the battery banks together so you could "jump start" from the house battery(s). A momentary switch is used so you don't accidentally leave the batteries connected continuously.

Hold the switch "on" while starting the engine if the starting battery(s) voltage is too low.

John K.

bgoetting · 03-30-2009, 09:35 PM

I had an embarrassing moment this weekend. While camping out in my '05 diesel E350, I let the vehicle batteries get too low. My RV battery was fully charged though. I couldn't find a way to jump start from the RV battery to the vehicle batteries. My friend has the switch mentioned above in his '02 SMB and told me that he could start his engine from the RV battery by using that switch. So what do I have in my '05? Do I have a seperator? If I had turned on the ignition and let it sit for a minute would the RV battery have kicked in? Is there a way I can test that now that all batteries are charged so I have some peace of mind?

I ended up getting a jump start from another guy, which was difficult because I had to climb under the vehicle and find the jump-post behind the second battery.

Bruce
'05 e350, diesel, smb 4x4, e-ph

John Kalmbach · 03-31-2009, 01:00 AM

You should have the Battery Separator on your '05 SMB. On your year model, turning the key to "on" for a few minutes should have helped. You can tell if the house battery is connecting to the starting battery by having the key "off", turn on the headlights, and after a couple minutes, note the voltage reading using the plug in volt meter at the dash 12 volt outlet. While watching the volt meter, turn the key to "on", you should see the voltage increase if the house battery is fully charged. Make sure you are not connected to shore power when trying this test.

In late '05/early '06 SMB started wiring the Battery Separator to the "start" circuit. You might want to have SMB change your wiring the next time you're in their area. This allows the house battery to boost the starting battery while cranking the engine, which is the correct manner in which the Battery Separator should work.

Thanks,
John K.

bgoetting · 03-31-2009, 08:36 AM

Thanks John for explaining this to me. This function of the separator is not explained in my SMB manual. I am unclear on this though. I had left my ignition on accidentally and the circulating fan drained my van batteries. If the separator links all my batteries automatically when my ignition is turned on for a few minutes, then why didn't I drain all my batteries when I did this? Does the seperator only provide power to the starter? Probably not if I can measure the voltage increase at the cigarette lighter in the dashboard. Confused

scatter · 03-31-2009, 11:42 AM

Quote:

Originally Posted by John Kalmbach

This allows the house battery to boost the starting battery while cranking the engine, which is the correct manner in which the Battery Separator should work.

This is the way my '07 works John, but the problem is (with the diesel) that when you turn the key to on to heat the glow pins, the house batteries are not helping the starting batteries and the glow pins do not heat up. When I turn to crank, the house ones kick in and the engine cranks fine, but takes a long time to start (especially when it's cold outside) without glow pin heat. I'd like to rewire it so the house batteries kick in when the key is in the on position. Any thots???