'nother question

[Paladin]

I've noticed that my batteries run down too quickly if I don't turn off the master battery switch. On a closer examination of things I noticed that on the idiot light panel, lower left corner there is a little blue light, I think it's within a light if memory serves. It says driver heat or something - going by memory here. I didn't even notice it being on until I did this in the dark.
This light is always on and nothing I do seems to turn it off. I'm suspecting a stuck relay but haven't gotten to tracking it down yet. Does anyone else have any experience with this?  Would the relay be in the electrical panel on the front left outside by the drivers seat?

Shouldn't my batteries hold their charge pretty long (like a car) even with the master battery switch turned on assuming I'm not leaving lights etc on?

-Dave

[Tenor]

My old GMC's main shut-off was toast and if I didn't disconnect the battery, they'd be dead.  In my MCI, I always use the disconnect and have had no problems.  I suggest that you use it and save the hassle.  Good luck!

[HB of CJ]

Unknown phantom loads can drive you crazy. What may have happened is that someone wired up some circuit that bypassed the master switch.  Things like some electronics, motion alarms, computer uplinks and stuff like that come to mind.  What you will need to doooss is measure the drainage load across the batteries with the master both on and off.   With that in hand, then you can figure out (maybe) what and where the load is coming from.  With older/modified coaches it is difficult to determine phantom loads as almost anything can/could/has been done including just plain unwanted old age continunity.  Good luck. 

[JackConrad]

For a quick "down & dirty" test, turn off the master switch, then remove the ground cable battery terminal and put a 24 volt bulb in series between the ground cable and battery terminal. The light should not be on if the master switch is OFF. If the light is on (or even barely glowing) you have a "phantom load". Remember that a 12 volt center tap off your batteries will not produce much light. I have seen phantom loads that would only make the bulb filament turn red, barely putting off any light.That's the easy part, the hard part is finding that phantom load. Could be anything from a radio memory to a bulb somewhere or whatever someone may have added. I would start be removing fuses/disconnecting circuit breakers until the light goes out. Hopefully a fuse/breaker will cause the light to go out and then you can check that circuit.  Jack

[gumpy]

. It says driver heat or something - going by memory here.

This is related to that part you were asking about the other day. You might want to check to make sure the wires off that temp sensor are not shorted somewhere.

Also, you probably need to open your dash and verify the wire number on the light that's on. Just because it says heat doesn't mean it's in the right hole. They're notorious for falling out and not getting put back in the correct hole in the dash panel.

[Brian Diehl]

Dave,
When you turn on the master ignition switch you also are turning on the voltage regulator.  The voltage regulator draws a lot of amps and will drain your battery in a hurry.  The voltage regulator is sensing voltage below the set point and is trying to get the alternator to put out more voltage.  Of course, the alternator is not turning and can not provide any power.  Therefore the voltage regulator goes to full output power trying to excite the alternator to put out the correct amount of voltage. 

Not all buses are setup this way, but many of the MC9 and 96A series buses are.

-Brian