Author Topic: Power draw  (Read 261 times)

bongo

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Power draw
« on: September 13, 2018, 05:32:22 PM »
Hi all

Well flat batteries seem to be my issue at the moment.
I have done a draw test and without removing fuses I sit at 1 amp no ignition on.
Removing fuses I found the "heater" circuit has a draw of .6 which then leaves the vehicle with a standby
of .4 which is with in spec.

My question is: Is there a common fault location for this circuit or should I just start the hunt ?
Thanks

firebirdparts

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Re: Power draw
« Reply #1 on: September 14, 2018, 06:13:34 AM »
You might expect to find the dome light, glove box light, trunk light on.  A power antenna might be something to suspect.  Bad diodes in the alternator can draw big amps in any car.

Other than those obvious items, I can't think of anything.  I would say 0.4 is way too high.  Does your clock run?  A lot of them don't these days.  What year is the car?

P.S. I would also add I don't think the heater fuse drawing power is all that common.  The heater wire itself has a dedicated set of contacts in the ignition switch, and if those don't open, the fan would run.  There may be some other items on that fuse, but I don't remember.
« Last Edit: September 14, 2018, 06:15:23 AM by firebirdparts »
I want to be like Paul Kenny when I grow up
Joe Bays
1977 Y82 4-speed (red interior)
1978 Skybird 350
1978 Redbird 305
1979 Redbird 301 4-speed
1992 Lincoln Mark VII LSC/SE (red)
1970 Datsun Pickup
1953 Chevy pickup (converted 4x4)
1988 T-bird Turbo Coupe

bongo

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Re: Power draw
« Reply #2 on: September 15, 2018, 04:47:41 PM »
Thanks for the reply.

Yeah the clock still runs 78 FB.
Most sites on auto elec state that a low current draw is acceptable about.4 thats why I said what i did.
I removed all lights to ensure no circuit leakage as a first thing as lights was what I went to as well.

Guess Ill have to dig up a diagram and start tracing.
I am assuming disconnect the alternator to check for bad diodes whilst running?

Yes, I thought the heater circuit would only power when the switch is activated... alas I was wrong.

firebirdparts

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Re: Power draw
« Reply #3 on: September 15, 2018, 06:47:36 PM »
I don't think having it running would help at all. If you unhook the charge post while you are checking power draw, you will see if that helps you.  If you want to.
I want to be like Paul Kenny when I grow up
Joe Bays
1977 Y82 4-speed (red interior)
1978 Skybird 350
1978 Redbird 305
1979 Redbird 301 4-speed
1992 Lincoln Mark VII LSC/SE (red)
1970 Datsun Pickup
1953 Chevy pickup (converted 4x4)
1988 T-bird Turbo Coupe

Re: Power draw
« Reply #3 on: September 15, 2018, 06:47:36 PM »
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