Gauge on the Dash

[Redpower33]

I was wounding what the ALT light on the 78-79 Bronco means?? I will be driving the bronco, and from time to time the light will come on for a second or two and I was wounding what this means? Any info would be great.

Thanks

 

[Broncobill78]

Well, the *short* answer is that when the ALT light comes on the alternator isn't providing enough voltage to keep the battery charged. Generally speaking this is due to either a dying alternator or *exceptionally* low engine revs (it's usually the alternator), bad voltage regulators DO come into play here but only rarely If you want/need to see scans from the factory manuals I'll be happy to find/scan & post them but it may take me a day or three. Have you used a meter to see what the engine/alternator is *outputting* while it's running ? Ck it across the battery terminals while the engine is running, what's the number ?

 

[BroncoJoe19]

I'm not sure if the older truck had only ONE belt or a few of them, but it could also be caused by a slipping belt to the alternator.

 

[Broncobill78]

Yup, excellent point. The 78/79 Broncos were all multi-belt deals. As I recall there were two, one ran the fan & PS pump while the other was for the Alt but it's been so long I'm really just guessing & anyone who actually *owns* one will surely correct me /emoticons/[email protected] 2x" width="20" height="20" /> The point remains the same, a loose belt will cause the alt to spin more slowly & since it's rev Dependant it won't produce the correct voltage, it won't charge the battery & it'll light the light.

Good catch Joe.

Just as a piece of obscure trivia (no more points, I got hosed last time. Damn cable documentaries ruin it for everyone who learned these tidbits the hard way, by mopping decks when you didn't answer within seconds) Ford pioneered the use of the Serpentine belt when they were first installed on the 79' Mustangs. I'm not for sure what year they finally progressed to the Bronco's & F-trucks but next time someone asks you when the first serpentine belt was used & by whom you'll earn yourself a candy bar (or at least the right to gloat)