Electrical issue, stranded at work.

[FrankSG]

Hi everyone,

I'm in desperate need of some electrical help with diagnosing my Bronco. This has been an ongoing issue. I think that I solved it and it keeps coming back to haunt me.

The issues is that when driving, it appears to be draining the battery...enough so that if I turn it off, the battery has no juice to start it. Additionally when I am driving it, and I put a turn signal on the motor pulses as though it want to stall with every blink of the signal.

I replaced the alternator, think that it wasen't charging the battery. After replacing the battery and alternator, I thought that the problem was finally solved. I tested the battery voltage without it ruining and got between 12 and 14. running under full load (lights, wipers, etc...on), and was getting around 13-14V. When I arrived at worked today, I barely made it in the parking lot before it died. (it wasen't a good first experience bringing it to work and having to push it into a parking space).:-[ I tried to crank it over and all I got was a few weak turns out of the starter before it completely died. The interesting part is that the headlights appeared to be bright.

I am going to try and get an Ohm meter at lunch to test the battery.

I'm not the best at electrical, so any help or ideas in diagnosing the problem would greatly appreciated.

Thanks ahead of time.
Frank

 

[lsukevinc]

could be the voltage regulator. it is the small box on the fender near the solenoid. I had a bad one that drained the battery for years in my 76 before i figured it out. they are relatively cheap and easy to change.

 

[bronconut73]

could be the voltage regulator. it is the small box on the fender near the solenoid. I had a bad one that drained the battery for years in my 76 before i figured it out. they are relatively cheap and easy to change.

Me too.....

 

[Justafordguy]

Voltage regulator would be my first guess also but you can test the rest of the system by bypassing the regulator and full fielding the alternator. When you do this you should see over 13.5 volts on your battery with a volt meter. If you do them it's your regulator for sure.

I guess I should explain the test a little better. To full field test the alternator you connect the A and F wires in the voltage regulator plug.

 

[FrankSG]

I have a new 100 amp alternator installed (2G). I know that I'm not exceeding the 100 amp rating. Is the voltage regulator internal too the alternator? Unfortunately I'm not a good electrical guy. Is it possible that I could have the wires on the solenoid crossed? The engine cranks with no issues.

 

[Justafordguy]

If the alternator isn't stock we will need more info before we will be able to help. Maybe post some pictures of how you have it installed and wired up? A volt meter on the battery posts will still be able to tell you if it's charging, that's your first test.

 

[lsukevinc]

I have a new 100 amp alternator installed (2G). I know that I'm not exceeding the 100 amp rating. Is the voltage regulator internal too the alternator? Unfortunately I'm not a good electrical guy. Is it possible that I could have the wires on the solenoid crossed? The engine cranks with no issues.

someone correct me if i am wrong, but only the 3G and above have an internal voltage regulator. so even if you replaced the alternator with a period correct one, it should still have a separate external regulator.

 

[Boss Hugg]

Check the body ground. We had a similar issue with a 76 where you'd hit the brakes and the brake lights actually became a ground for the ignition (or vice versa), killing the engine. After pulling all wiring and not finding a bad spot anywhere, I replaced it. When I put the battery back in and hooked the ground cable to it, I realized the body ground tab was not connected. Fixed that and the problem went away.

I think your lights are grounding or pulling voltage from the ignition or it could be that the only ground the lights are getting is back thru the ignition, which is almost inconceivable, but possible. If the body is grounded to the engine but not the battery, the only way the lights get a ground is when the ignition is on--if that makes sense. It's been about 6 years now, so the explanation escapes me.

 

[1strodeo]

If you are going to an auto parts store to buy your multi-meter, take the battery with you, have them charge it and pick it up after work. Electrical testing is useless without a fully charged battery.

Your voltage regulator should look something like the attached pic, with wires connecting it to the alternator. good luck

 

[svastano]

My guess would be voltage regulator too. Had an old JD that kept draining the battery and it was the regulator.

 

[Lunar-tic]

I had a similar problem, my voltage regulator was not properly grounded.

 

[Rustytruck]

You don't say what year Bronco, so very early Broncos had the voltage regulator mounted to the inner fender behind the battery where the solenoid is. Later models had it mounted on the firewall above the heater hoses going through the fire wall. either location the voltage needs good ground to the body through the mounting bolts. Unbolt and clean bare steel under the voltage regulator and fender.

Next make sure there is a ground wire on the battery post to the steel body. And a heavy battery cable from the negative battery post to the engine block. Make sure connections are clean and bolted tight on both ends.

Running the engine with poor grounds can create a whole host of problems.

If your voltage regulator has a tall cap on top of it about 2" tall change it to a Motorcraft electronic regulator which is a little over 1" tall.

 

[kylakekevin]

Like others have said grounds and regulator. Grounds are easy and cause the biggest headaches seem like. I had the tall cap regulator on my 67 and when it went bad it was sending 18 volts to everything!