bronco II lighting

[adrian p]

The bronco seems to have all the lights running off the alternator only.The headlights are led from the previous owner and work fine.its like driving a two stroke at night. Any recommendations would be appreciated.

 

[Uncle Gump]

That's pretty much the way it works... alternator runs all the accessory loads.

Curious... is the battery light on? What is battery voltage with engine running?

Alternators actually generate AC. It gets rectified to look more DC. If you have a bad diode in the rectifier bridge it can make lights pulse.

 

[adrian p]

thanks for the reply.no battery light on. Havent checked battery voltage while running but never had a an issue with starting so never really checked. Ill look into that rectifier bridge diode. Also the dash lights are dim, the dimmer works but it never its too bright.

 

[Bronco 2 man]

My instrument panel lights have always been dim! I know what you mean about the 2 stroke ordeal also. All my lights brighten up when I press accelerator! Done it ever since I’ve had mine. Thought the same as uncle Gump maybe having a diode issues! Checked everything out and all was good, so I don’t worry about it! I have an 85 Bii and it doesn’t have a high amp alternator. Actually in my opinion it’s pretty weak! In reality the more electrical stuff you have like power windows, fuel injection, etc. you have to have enough amps to run it. The less you have, you don’t need as much! My alternator only puts out about 70 amps, which in turn will run the truck. Not sure of your bronco!? It’s something to think about! Always had older vehicles and none of them had a very good charging system, just enough to work. Lol Sorry about my post being so long!

 

[adrian p]

afternoon gents. my alternator was tested by pepboys and autozone both said it was good but i only have battery volts at the battery.any help would be appreciated

 

[Bronco 2 man]

How many volts?

 

[adrian p]

just under 12 before starting. with engine running it drops down to 11

 

[Bronco 2 man]

What year is your bronco? Battery fully charged? 11 volt’s at idle? What about revving the engine at about 2,000 rpm’s, how many volts? Why I asked about when revving at 2,000 rpm’s, diode’s could be bad. Went through 5 on a Nissan pickup back in the day, before I got a good one! Which it’s odd to get that many bad! Is your voltage regulator on the firewall or built internal within the alternator? Have you checked out wiring for resistance to insure all is good! A lot of variables when checking electrical systems.
Battery must be fully charged or you will get incorrect reading’s for starter’s! Check wiring for resistance if all good! Battery is in good working order (meaning fully charged and no bad cell’s)! Part’s are made cheap and seems to be almost as many bad as they are good! If everything else check’s out good with the wiring and battery, no question about it, you have a bad alternator!

 

[Bronco 2 man]

My girl’s Colorado was showing like 8or 9 volt’s one day when I checked it! She drove up one evening and her light’s were dim! Had AutoZone test it! 4 time’s it was reading fine on there machine! Was fixing to leave and made them check it again and it failed 2 time’s in a row! Just saying dude!


Check everything if the truck is good, it leave’s nothing else!!!

 

[adrian p]

its an 87 with a 97 explorer 4.0. i will ring out the wires tonight and see what the situation is.i believe the regulator is built into the alternator since its a newer style for the 97

 

[Bronco 2 man]

Should be internal regulator! Should be around 13 or more running at idle! Light’s on about 13.8to to 14.5!

 

[adrian p]

thanks very much

 

[Bronco 2 man]

No problem

 

[Perkinator104]

How do the lights look when the engine is off and you just turn on the headlights from battery?

 

[adrian p]

found a burnt wire connector and fixed that so now the alternator is working but the wire is getting super hot(thus the burnt connector) so im gonna follow the wire back to the starter relay and try to figure out why im getting such high resistance to get the wire that hot. not sure if the battery is drawing that many amps to cause the wire to get that hot.

 

[Bronco 2 man]

Awesome dude at least you making some head way! Sure you will figure it out!!

 

[JerryC]

Alt 86 harness was made for about 50-60 amps I think. If the alt came with the 4.0 it may be way above that and you need up the wire gauge.

 

[Bronco 2 man]

JerryC make’s a good point.