Battery Charging - load is toggling on meter (Page 1/1)
mtgjudge SEP 25, 11:36 AM
Hello PFF!

So, I went to go charge the battery in my Fiero today (10A charger) and I am getting a loud humming coming from underneath the driver's side headlight motor. When the loud humming commences, the meter on the charger shows a charge underway, but then after a few seconds the humming stops and the meter falls. Moments later, the humming starts again. Rinse, repeat. I've never had this issue before. I have a brass battery disconnect (which apparently was not unscrewed enough, hence the dead battery). Can anyone help me troubleshoot? Thanks!

[This message has been edited by mtgjudge (edited 09-25-2021).]

imacflier SEP 25, 12:22 PM
What year Fiero? It might make a difference: Gen1 vs Gen2 headlight system.
mtgjudge SEP 25, 12:24 PM
1986 GT.
imacflier SEP 25, 12:29 PM
Sorry, mine is an '88 so gen2 HL system and my FSM does not cover the gen1 SL system. Have you used search and, especially gone to ogre's cave??

Likely you will find your answers there....if someone here does not walk you through troubleshooting.

GL

Larry
mtgjudge SEP 25, 12:37 PM
I'm pretty sure it has nothing to do with the headlights; I'm just using that as a reference for the sound's location. I assume there is a solenoid there or something.
buddycraigg SEP 25, 09:03 PM
I think you have a problem with that head light motor.

unplug the motor and see if the sound / battery draw goes away.
cebix SEP 26, 10:35 AM
I'm 99% sure you have a problem with that headlight motor not shutting off. That's why you're charging your battery right? Cause you've got a drain?

Now when that motor starts it pulls some current until it overloads and shuts off. And when the thermal circuit breaker cools down it starts again and so on.

Unplug that motor and fix the limit switches inside.
Dennis LaGrua SEP 26, 11:40 AM

quote
Originally posted by mtgjudge:

I'm pretty sure it has nothing to do with the headlights; I'm just using that as a reference for the sound's location. I assume there is a solenoid there or something.



I would not be so fast on that conclusion. The Gen 1 headlight motors are old and known for a motor open problem even when closed. What happens is that the motor gear inserts disintegrate and the shaft doesn't close the limit switch and shut off the power at the end of travel. Unplug the motors; (a five minute task) and that may save you time pinpointing the problem. .

------------------
" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

mtgjudge SEP 26, 01:10 PM

quote
Originally posted by Dennis LaGrua:


I would not be so fast on that conclusion. The Gen 1 headlight motors are old and known for a motor open problem even when closed. What happens is that the motor gear inserts disintegrate and the shaft doesn't close the limit switch and shut off the power at the end of travel. Unplug the motors; (a five minute task) and that may save you time pinpointing the problem. .




And this is why I love PFF! Thanks for the tip. That would have been very far down my list of items to troubleshoot. Assuming that it is bad, are there aftermarket replacement parts available?

Sadly, my Fiero has sat idle for several years due to "life", but I anticipate having some more time in the coming months to work on it and would add these to the list.

Thanks again!

[This message has been edited by mtgjudge (edited 09-26-2021).]

buddycraigg SEP 26, 03:24 PM
you only have to unplug the single blue wire.