Potential low power (Page 1/2)
Josh86gt MAR 16, 09:03 PM
I was taking my fiero for a spin earlier today and the battery meter was only reading 13 volts which I thought was weird it seems a tad low and when it got darker I went to turn on my headlights and they only went up about halfway I had to hold the switch half on half off for them to go up fully would this be a weak alternator?
Patrick MAR 16, 09:43 PM

quote
Originally posted by Josh86gt:

...would this be a weak alternator?



Probably. Should be showing a charge of more like 14.6v

Josh86gt MAR 16, 09:46 PM

quote
Originally posted by Patrick:

Probably. Should be showing a charge of more like 14.6v



Okay thanks it's been worrying me for a while some of the lights on my dash also flicker but that could just be a loose connection
Patrick MAR 16, 10:02 PM
Before changing the alternator... make sure the connections (on battery, power junction, and ground) are corrosion-free and tight. Use a standalone volt/multimeter to measure what the alternator is putting out.

[This message has been edited by Patrick (edited 03-16-2025).]

Vintage-Nut MAR 17, 09:01 AM
Start with a fully charged battery as the Generator/Alternator will not even try to charge an undercharged battery...

Use a voltmeter to measure the battery - 12.5 DC Volts or Better
*If the battery won't hold 12.5V after charging - replace it

Check the Generator/Alternator Belt Tension

With a fully charged battery...
Use a voltmeter to measure the battery at idle AND 3k RPM - 13.5 volts to 14.5 volts
*If the Generator/Alternator won't charge the battery at 13.5 volts to 14.5 volts...then

Check the Generator/Alternator Connections
With the KEY at RUN position {Engine NOT Running}
Check All Cable/Wires Have 12V
*If NO, check the fuses/wires/cable
*If ALL have 12V - replace the Generator/Alternator

------------------
Original Owner of a Silver '88 GT
Under 'Production Refurbishment' @ 136k Miles

[This message has been edited by Vintage-Nut (edited 03-17-2025).]

Josh86gt MAR 17, 07:01 PM
Okay so I finally got around to testing my alternator and it worked just fine but my headlights still seem to not go up when I flip the switch all the way I have to hold it halfway and some of the lights on my dash tend to flicker when I turn them on would that be a bad headlight switch?
Vintage-Nut MAR 17, 07:13 PM

quote
bad headlight switch?



Start there, you can try cleaning it or:

The Fiero Store Headlight Switch / Part # 51426
https://www.fierostore.com/.../Detail.aspx?s=51426

AC Delco
https://www.partsgeek.com/v...eadlight-switch.html

Wells
https://www.partsgeek.com/f...eadlight-switch.html

Standard Motor Products
https://www.partsgeek.com/4...eadlight-switch.html

Edit for a Warning
The headlight switch is HOT at All Times!
Disconnect the battery before removing the switch

[This message has been edited by Vintage-Nut (edited 03-18-2025).]

Josh86gt MAR 18, 06:25 PM
Okay so I finally got around to taking out the light switch does anyone know how to disassemble it without breaking it?

Vintage-Nut MAR 18, 09:17 PM
If it is sealed - 'flood' the unit with electrical contact cleaner as flipping the switches

Fully Dry It, and Test It...
Josh86gt MAR 18, 09:18 PM

quote
Originally posted by Vintage-Nut:

If it is sealed - 'flood' the unit with electrical contact cleaner as flipping the switches

Fully Dry It, and Test It...



Ok thanks