BAC Forum
General Boards => Technical Support => Topic started by: Ramona Key on April 27, 2020, 12:32:39 AM
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I need to find the fuse location for the battery boost rocker switch. It does not appear to have any power going to it. No control power being received at the big boy from the switch. In order to start coach I have to use a cable clipped from house battery to chassis batteries. It starts without hesitation then so it's not the batteries themselves that are the problem. Any info on fuse location or a wiring diagram would be appreciated.
Charlie Key
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Charlie,
Check the 07 Patriot wiring diagrams in Coach Assist. The vast majority also apply to the Marquis. The Boost switch switches ground, not 12v. The only 12v on the switch is for the switch illumination..
Steve
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Charlie,
Your coach should start without use of the Boost solenoid. So if the coach will not start without combining the two battery banks together, you have an issue with your chassis batteries. Either they are discharged, probably from an inoperative BIRD system, or they are in need of replacement. But never replace batteries until you are sure that everything in your charging systems is functioning properly.
Gerald
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Charlie,
I'm pretty sure the boost solenoid is shown on sheet 76 of 194 in the 07 Pat Thunder wiring diagrams. Dwg # is 38070196. Dwg title is Schematic Switches Battery Cutoff. It shows the control wires for the solenoid running to a module but I can't read the label. I'm pretty sure it is a rear run box module. They contain fuses so that may be an area to check.
Steve
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Charlie,
The module in the diagram that Steve is referring to is called the BIRD-Battery Control Center (BIRD-BCC), it is located in the Rear Run Box. The BIRD-BCC controls the Big Boy relay and the 12-volt house disconnect relays (‘salesman switch’). The dash mounted START BOOST and BATT CUT-OFF switches are both connect to the BIRD-BCC.
There are two small yellow test buttons on the BIRD-BCC, one will energize the Isolation Relay (Big Boy Relay) and the other will cycle the two 12-volt disconnect relays. The test button for the Big Boy is labeled ‘ISO Relay SW’, pressing this button simulates pressing the START BOOST switch.
There is a green LED on the BIRD-BCC labeled ‘ISO Relay ON’ that will be illuminated when the BIRD-BCC is sending a signal to the Big Boy coil. This LED should be illuminated when connected to shore power and the inverter/charger is charging at least 13.3-volts.
There are also two 7.5-amp fuses on the board, one for the BIRD circuit and one for the BCC circuit.
While on shore power, if your house batteries ARE maintaining a charge but your chassis batteries ARE NOT, as Gerald mentioned, your BIRD system may be faulty.
You can use your Aladdin system to do some preliminary troubleshooting.
Connected to shore power with the inverter/charger charging at least 13.3-volts, turn the ignition key to the on position (engine not running) and compare ‘Battery’ voltage on the ‘Engine/Trans’ screen (chassis batteries) to the ‘House Bat’ voltage on the ‘Coach Electrical’ screen. Both should be at least 13.3-volts and should be within ~.5 volts of each other. If the chassis battery is reading less than the house battery your BIRD system is suspect, it could be a corroded Big Boy.
If you find that your BIRD system is suspect, you can try cycling the Big Boy relay with the START BOOST switch or the BIRD-BCC test button several times, this might temporarily clear any corrosion. This assumes that the Big Boy is engaging but not joining the two battery banks together. You will need to be disconnected from shore power, engine and generator off and the Big Boy initially disengaged.
I've attached an image of the Rear Run Box and the BIRD-BCC.
Scott
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Steve
Scotts post might be a good troubleshooting aid in the electrical section of the technical library as there is nothing there are the newer style bird control.
Just a thought
Eric
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Let me consider it.
Thx, Steve
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If this Big Bird check was added to the library you might add to it that the first thing is to test the voltage across the Big Bird, I have to remove and clean mine about once a year, also carry a spare which is cleaned and ready to install. I usually notice that the Bird is in need of a swap out going down the road and the house battery's are not charging from the alternator.
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Thx, Wil add to Common Problems.
Steve
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I've just purchased this unit and the issue was never addressed. Just got home from a 1300 mile trip, unit in parked at the house and will trouble shoot this with the info provided. I hate spending money on something I can fix with the help of the members of this forum. The unit has some gremlins and I hope to get them sorted.