Please tell me I haven't screwed it up too bad.

[bannind]

Frustration was setting in as to why my bronco wasn't wanting to start properly.. Thought I might be having a timing issue because it started up in the morning just fine - it simply wouldn't restart.. Nope that wasn't quite it. Had a new battery, big health strong one. Nice 0 gauge cables. I even added in an extra ground cable from the block to the frame.. Then as my wife looks around the engine bay as I rant in the garage demonstrating the depths of my vernacular, she calmly asks 'so what is this wire for'? I look at the wire she is holding and want to hang my head in shame.. I had forgotten to hook up the 'hot in run' wire for the alt. Thus my alternator has not been turning on for the last 2 weeks.. Have I done any dmg to the alternator since the wire was probably grounded all the time or is it just the dmg to the pride over forgetting the simplest of things?

Thanks,
dan

 

[SaddleUp]

Is this a 3G alternator or just the original Bronco alternator? If it's the original one then I think the alternator is probably fine but it may have effected the voltage regulator. If it's a 3G then it's probably toast. (They will blow diodes if they are charging without the battery hooked up) Either way yank it out and run it to the nearest parts store. Almost all of them can test it to see if it's working or not. Warning though... If you don't trust the parts store then run it to a couple of them if the first one says it's bad. I've known them to tell me one was bad when it actually wasn't. Also if possible find one that has the machine out where you can watch them test it. If it is then they will be more likely to be honest about it since several of us already know how to test them ourselves but just don't have the equipment to do it.

 

[Ryan]

I had forgotten to hook up the 'hot in run' wire for the alt. Thus my alternator has not been turning on for the last 2 weeks.. Have I done any dmg to the alternator since the wire was probably grounded all the time or is it just the dmg to the pride over forgetting the simplest of things?

Thanks,
dan

I would think the alternator is okay. Charge up the battery overnight / hook up the alternator / start the engine / measure battery voltage. If you get ~14.4 volts, you are good, but anything less is a problem.

 

[bannind]

Well fully charged the battery last night - then this morning I am getting 12.8volts with it running. 12.6 with it running with lights on. This is the reading whether I am connected too the alt positive connection or the battery positive. I can definately tell a different sound in the engine with the alternator being turned on. So is this telling me new alternator?

 

[gearida]

I would have to say your ok. Because you just charged up battery completly so your alt. doesn't have to, it sees a full charge. So, check your voltage of the battery without the Bronco running and compare the voltage to running voltage. Does it increase with the alt. turning? Apply a load to the system either with a tester or by adding all of the electrical equipment in the Bronco "on" to see if your voltage is affected higher then chances are good you'll be fine. You mentioned sound of the alt. you got me about that, it would really be what type of sound do you hear?

 

[SaddleUp]

Sounds fine. When the battery is fully charged it isn't going to output full voltage. The sound referenced is the drag on the motor when the alternator kicks in which is normal and also indicates that it is actually charging.

 

[DirtDonk]

I disagree with you guys (for once). Even with a fully charged battery, the alternator should still be putting out well over 13 volts when running. The fact that he read even a slightly lesser amount (only .2 volts) with the lights on says that the alternator is not charging properly. The different sound you heard with the alternator on is a good sign, but you're still reading low in the voltage department.

Even just starting the engine on a fully charged battery will cause the alternator to put out a good charge initially to bring the battery back up from that short 250 amp (or whatever it is) draw that the starter pulls.

So I say that barring some other issue with the connecting wires, you should have the alternator checked out at a local shop. Keep an eye on your battery charge to see if it just keeps going down.
If it maintains it's roughly 12 volt status, then your alternator is at least putting out something. Just not enough.
You can tell for sure by doing the same test you just performed, but turn on the high-beams, heater, radio, emergency flashers, and anything else you can think of, and see if the voltage starts to drop.

Bottom line is a fully functional alternator should give you a reading of over 14volts with the engine running. Especially at a high idle.

Paul

 

[Broncobowsher]

I think there is other problems as well. Before I condem it as bad, what is the battery voltage with the engine off compared to running?

12.8 or 12.6 running isn't charging unless the battery is very, very low or the regulator is bad. I have heard of an alternator pulling a huge load on the engine but not charging the batery, can't remember what the problem was. That was a '67 mustang that was the ex-landlord's girlfriend's car.

 

[SaddleUp]

If this is an original alternator rather than a newer internally regulated one then simply disconnect the ground lead on the battery while it is running and see if it stays running or not. If it dies then it's not charging. Don't do this with an internally regulated alternator though.

My voltage normally reads around 12.8 volts. If I use my winch and draw the battery down then it pushes upwards of 14 volts until it catches back up again.

 

[Socal Tom]

If the battery is fully charged, and the voltage drops with the lights on, then the alternator isn't charging. Fully charged batteries are 13.2 volts. Take the alternator to the parts store and have them test it.
Tom

 

[bannind]

It is a 4g alternator - from an explorer serpentine setup. I am taking it in to the shop tomorrow to get tested. If it is bad, should I just move up to a 6G alternator from a 99-07 ford diesel? Or am I going to have major issues with the plugs and such?

 

[broncnaz]

Dont forget most alternators dont put out much at idle. Some dont charge until 1000+ rpm. But still drive it down to the the parts store and have them test it.

 

[bannind]

That's probably not a bad idea. Instead of taking off the alt and heading down, I will just drive it down. Witha fully charged battery I am pretty sure it will make it down there and back ok.