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Old 02-12-2012, 01:18 PM   #1
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AUX Start Problem

I decided to clean and treat the chassis battery terminals today. I disconnected shore power and disconnected the chassis battery. I thought with the chassis battery disconnected now would be a good time to check the AUX Starting System. With the chassis battery disconnected I turned the ignition key on and all the dash lights came on I pressed and held the AUX Start switch and turned the key to start. The engine fired right up and I thought great the system works. Then it hit me the dash lights came on with the chassis battery disconnected. I turned off the engine then turned the key back on and the dash lights came on again. I then turned the key to start WITHOUT pressing the AUX start switch and the engine started.
Looks like I might have a AUX Start relay stuck in the connect position tying the chassis and coach batteries together. I listened for a click when pressing the AUX Start switch and do not here anything. To cold out to troubleshoot anymore today. Will post more later.

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Old 02-12-2012, 01:46 PM   #2
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it is possible for a relay of any type to 'weld' the contacts together from the arc produced. If you disconnect power to one of the coil studs (some solenoids only have one & the case mounting bolts are the ground) & read ~zero resistance between the fat cable studs, contacts are welded, time for new solenoid.

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Old 02-12-2012, 02:03 PM   #3
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Sounds like something is stuck but hey, at least you know you can start the coach.
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Old 02-12-2012, 02:13 PM   #4
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The way ours is wired, as long as the coach batteries (first priority) are at close to full charge then the solenoid is on so as to charge the chassis batteries (second priority). (typical when the shore power is connected for a Intellitec BIRD system).

This may be your current state with nothing wrong at the solenoid. To test this theory you could first have someone back at the solenoid to listen for the click when aux start switch is pressed. If no click (like you said) then disconnect 1 power wire from the solenoid coil and listen for the click to disengage.

The way I know this is our solenoid typically has a buzz when energized (A result of the BIRD reduced holding voltage dropping slightly below what it takes to hold it in after the initial latching voltage triggers the solenoid) I simply pull the red spade wire going to the BIRD module "relay" position for the solenoid to open up and not buzz. This separates the contacts and isolates to 2 battery systems.

Its designed to run this way when on shore power (without the buzz from an aftermarket solenoid). When the engine is running it works in reverse so the chassis batteries get charged (first priority) from the alternator before the solenoid closes and charges the coach batteries (second priority)

When all is charged (most of the time ) the solenoid is energized connecting the 2 systems together.
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Old 02-13-2012, 01:19 PM   #5
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Problem solved, actualy no problem. Seems the Aux Start relay latches for about 20 seconds when the Aux Start switch is pressed and released. What I did when I checked the Aux Start was press the Aux Start switch and listen for the relay click. When I did not here it I turned the key on the dash lights came on and I started the engine. This was with the chassis battery disconnected. Not knowing the Aux Start relay latches for about 20 seconds I thought I had a problem.
This morning with the chasis battery still disconnected I tried to start the engine without pressing the Aux Start switch. The dash lights did not come on and the engine did not start. With the ignition on I pressed the Aux Start switch and the dash lights came on I released the Aux Start switch and they stayed on for about 20 seconds. With the ignition still on I pressed and released the Aux Start switch again and the dash lights came back on. I turned the key to start and the engine started. So it seems there is no problem after all.
I thank everyone for the responses.
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