Hunting a voltage leak

[Steve McMahan]

Does your regulator still have the external condenser on the side of it? It’s the radio condenser. I would disconnect it and see if it eliminates the draw. Also, as you’ve said, it could be a short or a stuck contact in the regulator. Just more things to check.

 

[73inNH]

I just ran out to check the condenser. I unplugged it and the draw was still there.

Of curiosity, what does the condenser do?

 

[cv_72mustang]

Radio noise filter.

I use the wiring diagram/schematics to track and trace these issues down.

 

[73inNH]

Replacing the voltage regulator worked. A little frustrating because the one on there is only a couple of years old.

I used a Duralast VR730. Note that there are two duralast voltage regulators specified for this vehicle. You need to check your alternator size to be sure you get the right one. The VR730 was specified for my 55 amp alternator. The 90 amp alternator takes a different model number.

i'm glad it's fixed. There's some wiring down there that's pretty funky so I will spend some time cleaning that up and replacing the voltage regulater wiring harness as well.

Thanks for the support!

 

[midlife]

That's not the voltage regulator, but the starter solenoid in your picture.
I'm not familiar with alternator harnesses, so I can't tell you what that wire is or where it should be attached. The alternator/voltage regulator harness is different if you have an ammeter vice an alternator indicator lamp, so it could be you have the wrong harness installed.

Typically, a yellow wire at the voltage regulator (flat 4 pin connector) is an input to the VR that signals what the battery voltage is.

 

[mrgmhale]

I am glad you got it figured out. Thank you for the updated info. It is nice to see that several folks were willing to pitch in and help with such a frustrating situation.

 

[73inNH]

Closing the loop on this . . . . I also replaced the Voltage Regulator harness as the original wasn't a tight fit (you could slide it off with no friction) with a Dorman 85842. The harness has a few extra wires, but fits good.

On to the next job (tune up on my kid's 87 300zx)!