Need Help w/Mystery: Extra Wire from Alternator and Continued Discharge

[firemarshalbi11]

Hi All,

I've got a 73 ford bronco that recently started having a charging problem. Symptoms: When running, the battery discharges/does not charge.

Troubleshooting done: Have removed all extra equipment (winch, radio, CB, etc). Have tested for current usage with key turned off - no current used. Have replaced the battery, had the alternator checked (multiple times), and replaced the regulator. Have done an initial check of all wiring - no obvious shorts.

Questionable wire: Have found a wire from the wiring harnes coming from the alternator that is not connected to anything. Wonder if this is the problem, however, on investigation, no male connection found within reach of lone female connector from alternator.

Any ideas or help to troubleshoot would be very much apprieciated. ?:?

Thanks,

-FMB

 

[70_Steve]

Welcome firemarshalbi11!

A little extra information might be helpful.

Stock alternator?

What color wires are connected to the alternator, and where?

What color wire isn't connected??? And which direction does it go?

 

[firemarshalbi11]

More details on the wires

Thanks for the Help!!!

The alternator is not the original, but it is stock.

All wires are connected to alternator (four total: 1) Red, 2) large black & yellow, 3) black & white, and 4) black). However, the black & white wire is not connected to anything except for the alternator.

Description of wires: The red, black & white, and black wires come to the alternator from the wiring harness from the firewall. The Black & white wire enters the grouping of wires just before the ground bolt holding the group of wires to the alternator. From there, the black & yellow (mystery) wire connects to the bottom most post (snap on connection) on the back of the alternator and has a black dust boot. The large black & yellow wire connects to the back of the alternator by a nut and has a larger black dust boot. The red wire connects to the alternator using a snap on connection to a post near the center of the back of the alternator and has a red dust boot. The black wire is believed to stop inside the group of wires as it connects to the back of the alternator (as a ground).

Sorry for the book , hope it makes sense.

-FMB

 

[Viperwolf1]

The white-black wire should be connected to the alt STA terminal. It's for the electric choke.

 

[70_Steve]

This will be easier if you have a voltmeter available.

Remove the plug from the voltage regulator. (leave the regulator mounted to the fenderwell) Should be three wires (or maybe 4...) on the plug. The Yellow wire (might have two yellow wires) should have 12 vdc regardless of key position. The Green w/Red stripe should have 12 vdc when the key is ON. The other wire (Orange) should go to the alternator (Maybe your Red wire?).

 

[DuctTape]

I had the same problem, chased it everywhere. Not sure if this is applicable to your problem, as my alternator was not stock, so I wasn't using the external voltage regulator. My problem ended up being the alternator itself. A quick and cheap rebuild and voila.

How confident are you in the check of the alternator?

The way I was finally able to identify it was to disconnect components while checking for a drain until unplugging the alternator eliminated the drain.

I'm trying to remember the trick to checking for a drain - someone had it posted on these boards. Basically you use a test light but I'm hungover and can't remember the testing method for the drain - I think maybe it was just disconnect the positive terminal and put the test light in between the batt pos terminal and the batt pos cable.

 

[firemarshalbi11]

Ok, had a slight delay, but finally got ahold of a voltmeter and here are my findings:

With Key Off:
Orange: 12.55v
Green: 12.55v
Yellow: 0.03v


With Key On (not accessory mode, but as key would be if started and running):
Orange: 12.55v
Green: 0.22v
Yellow: 0.01v

Note: Have four wires as "70 Steve" described (reddish-orange, green, two yellows). One yellow connect to the other and goes to a small black tube like container mounted on the fire wall right next to the regulator (not sure what this is).

Also Note: the voltage was double checked as doesn't seem to be what "70-steve" predicted it would be. What does this mean?

Thanks!

 

[firemarshalbi11]

Also, Note: battery stays charged if vehicle not driven/key left off/vehicle not running. Seems to only discharge when vehicle running (worse/more noticeable by voltage gauge on dash when headlights turned on). Did the drain test of unhooking all accessories and with the key off, connecting a light tester between the negative battery cabe and negative battery post. Light did not light up (no drain when key is off).

 

[broncnaz]

Sounds like the wire running through the alt gauge is routed wrong. Unplug it and route it through the opposite way. Hook the volt meter up to the battery when running what do you get?

 

[Viperwolf1]

Ok, had a slight delay, but finally got ahold of a voltmeter and here are my findings:

With Key Off:
Orange: 12.55v
Green: 12.55v
Yellow: 0.03v


With Key On (not accessory mode, but as key would be if started and running):
Orange: 12.55v
Green: 0.22v
Yellow: 0.01v

Note: Have four wires as "70 Steve" described (reddish-orange, green, two yellows). One yellow connect to the other and goes to a small black tube like container mounted on the fire wall right next to the regulator (not sure what this is).

Also Note: the voltage was double checked as doesn't seem to be what "70-steve" predicted it would be. What does this mean?

Thanks!

Strange readings. Yellow wires should have battery voltage at all times. The cylinder is a capacitor. They should be hooked up to the battery terminal of the starter solenoid.

The green-red wire should have battery voltage with the key ON only. This turns the regulator and alternator on.

The orange wire is what controls the alternator field which in turn controls it's output. It's voltage will be high when the voltage on the yellow wires is low.

I'd start by fixing the yellow wires, then check voltages again.

 

[DirtDonk]

The small black ground wire should continue on up to the regulator and be attached to one of it's mounting screws.
Not that this should cause any of your problems, but it sounded like you didn't see it continue on up through the harness. It's hard to see though, as they're usually molded right into the rubber/plastic chunk on the back of the alternator and just looks like a way to hold the harness steady.

Were your readings taken with the regulator plug disconnected from the regulator? Or still connected?

What other modifications, if any, does your Bronco have? Big stereo? Any non-stock looking wires hooked to the starter relay/solenoid?
Anything else not working properly?

Paul

 

[firemarshalbi11]

Well all, the answer was a new alternator. Lesson learned, ask more questions even if the companies testing should know what they are doing.