Engine '96 altenator issue

Desync

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Apr 18, 2019
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Got a new to me '96 mustang from a guy at work. Supposedly its had another motor put in it and quite a few wires and hoses are cut and plugged under the hood, but it runs great.

One problem I'm wanting to fix is the altenator.

The green/red wire from the altenator was cut and had a red wire soldered to it and ran to the fuse box to the NOT IN USE fuse location.

With the wire unplugged the battery doesnt charge, with the wire plugged in, the battery charges but you have to unplug the wire when you turn the car off or it kills the battery.

I found the original green/red wire under the hood and hooked it back up to the altenator but it still doesn't charge the battery. So I chased the wire to the "battery light" inside the cluster and the bulb is good, then I changed the #18 fuse in the fuse box under the dash as it was blown, and still no charge.

The cluster had been taken out and the face was painted red to match the car and blue LEDs was put in the cluster. So I'm lost on what else it could be.
 
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wmburns

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Aug 14, 2009
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First. Are you positive that the correct alternator has been used for THIS application.

Next. Is the jumper between the two small terminals in place?

Did you recheck fuse #18 to be sure that it didn't blow again?

There's a 510 Ohm ballast resister that works with the battery charge light. We need to see if the circuit is actually complete. It's possible that the light is good but the ballast resister is bad.

Orrrrrrrrrrrrrrrr. If the battery charge light has been replaced with an LED I could see that affecting the over all resistance of the circuit. Best to make sure that a factory original bulb type is used.

With the key on, measure the voltage between the LG/R wire (from the cluster) and a KNOWN good ground. Post.

Does the battery charge light come on when the key is on? Next ground LG/R wire with the key on. Does the light come on now?

Note, you may find it very useful in this kind of trouble shooting to also use a test light. A test light will "load" the circuit in a way that a VOM will not.
 
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Desync

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Apr 18, 2019
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First. Are you positive that the correct alternator has been used for THIS application.

Next. Is the jumper between the two small terminals in place?

Did you recheck fuse #18 to be sure that it didn't blow again?

There's a 510 Ohm ballast resister that works with the battery charge light. We need to see if the circuit is actually complete. It's possible that the light is good but the ballast resister is bad.

Orrrrrrrrrrrrrrrr. If the battery charge light has been replaced with an LED I could see that affecting the over all resistance of the circuit. Best to make sure that a factory original bulb type is used.

With the key on, measure the voltage between the LG/R wire (from the cluster) and a KNOWN good ground. Post.

Does the battery charge light come on when the key is on? Next ground LG/R wire with the key on. Does the light come on now?

Note, you may find it very useful in this kind of trouble shooting to also use a test light. A test light will "load" the circuit in a way that a VOM will not.

I'm not 100% sure if the right alternator was used

The jumper is in place

I did re-check the fuse and it is not blown

The battery charge light is a factory bulb, when I turn the key to the ON position the only light that comes on in the cluster is the AIR BAG light.


I will have to get a test light and VOM tomorrow after workw and see what happens, obviously they couldn't figure out the problem, so they just cut the LG/R wire and just soldered in the other wire and plugged it into the fuse box. IF I can't figure out the problem, is there another workaround to where I don't have to keep popping the hood and plugging/unplugging that wire to the fuse box?
 

wmburns

SN Certified Technician
Aug 14, 2009
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Houston Texas
IF I can't figure out the problem, is there another workaround to where I don't have to keep popping the hood and plugging/unplugging that wire to the fuse box?
Yes. Power the alternator from a circuit that is active only in "run". Such as from I/P fuse #18 (the original circuit).

If this were my car I would make an replacement battery light by putting a 510 Ohm resister in parallel with a small incandescent red bulb so that you still have the battery warning function.

The Battery Junction Box (BJB) is not a good place to power this circuit from. Why? Because all of the BJB circuits are "always on".

An option is to power from the CCRM in the front right hand fender well. Tap the PCM line or the fuel pump line. But you will need to add an additional inline fuse to protect your ride from burning to ground. This option has the advantage of not having to snake a wire through the firewall. The down side is there's not an easy way to mount the battery warning charge light in a visible location.

If you are able to remove the cluster and are willing to perform some tests, I suspect that you can succeed where the prior owner failed (with some expert help).

If asking for someone to handicap this thread my vote is there's a burnt PC foil trace on the cluster. That is what caused the fuse to blow in the first place. Now the circuit is open (due to carrying a large current) and that's why the replacement fuse doesn't blow. Note, if you are handy with a soldering iron it is possible to repair a PC foil trace with a separate wire.

Cluster PC foil trace repair
https://www.allfordmustangs.com/forums/v6-tech/304608-my-odometer-goes-off.html#2657361

OBTW, when the key is first turned on, the cluster should go through a "lamp test" where ALL lights come on. So it would seem there's already something wrong with your cluster.
 
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Desync

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Apr 18, 2019
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Yes. Power the alternator from a circuit that is active only in "run". Such as from I/P fuse #18 (the original circuit).

If this were my car I would make an replacement battery light by putting a 510 Ohm resister in parallel with a small incandescent red bulb so that you still have the battery warning function.

The Battery Junction Box (BJB) is not a good place to power this circuit from. Why? Because all of the BJB circuits are "always on".

An option is to power from the CCRM in the front right hand fender well. Tap the PCM line or the fuel pump line. But you will need to add an additional inline fuse to protect your ride from burning to ground. This option has the advantage of not having to snake a wire through the firewall. The down side is there's not an easy way to mount the battery warning charge light in a visible location.

If you are able to remove the cluster and are willing to perform some tests, I suspect that you can succeed where the prior owner failed (with some expert help).

If asking for someone to handicap this thread my vote is there's a burnt PC foil trace on the cluster. That is what caused the fuse to blow in the first place. Now the circuit is open (due to carrying a large current) and that's why the replacement fuse doesn't blow. Note, if you are handy with a soldering iron it is possible to repair a PC foil trace with a separate wire.

Cluster PC foil trace repair
https://www.allfordmustangs.com/forums/v6-tech/304608-my-odometer-goes-off.html#2657361

OBTW, when the key is first turned on, the cluster should go through a "lamp test" where ALL lights come on. So it would seem there's already something wrong with your cluster.

I have the cluster out right now

EDIT: I chased the PC foil trace from the BATTERY light to the pin, and lo and behold the end of the foil was bent, I straightened it out and cleaned it off really good and plugged the cluster back up. Battery light and airbag light now comes on. I hooked the LG/R wire back up under the hood and battery is charging.

NOW that's fixed, time to move on to the next thing.
 

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wmburns

SN Certified Technician
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Just wondering. How useful was the help from the forums in your finding the "fix"?

How does it feel to trouble shoot such a fairly complex electrical problem? Where you surprised what you found?
 
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Desync

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Just wondering. How useful was the help from the forums in your finding the "fix"?

How does it feel to trouble shoot such a fairly complex electrical problem? Where you surprised what you found?
The help was amazing, I posted in other "places" with zero replies. Came here and you answered promptly and detailed. Would recommend this place to anyone.

How does it feel? freaking amazing, makes me want to learn even more now. Surprised, not really as seeing how some other stuff in the car is, but I was surprised that it was a simple solution to what I thought was fixing to cost me a pretty penny.

Really appreciate the help, should I be worried about any of the other lights? as the air bag and battery light are the only ones that come on now. Also, 2 lights on the right side of the cluster are just completely missing.

Now I gotta crawl my big butt under the car and plug the speed sensor back up and hope my speedometer and millage works. I get that fixed and I'll be tickled pink.
 
MAAAAN I have been away for way too long, We have Customer service replies now. WOW



On the 2 lights that are completely missing. Do you have a Pull A Part yard close???? IF so make a trip and you can pull a cluster out of a dash and get the bulb and seat socket easily. Plug and play, IF the circuit works
 

Desync

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Apr 18, 2019
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MAAAAN I have been away for way too long, We have Customer service replies now. WOW



On the 2 lights that are completely missing. Do you have a Pull A Part yard close???? IF so make a trip and you can pull a cluster out of a dash and get the bulb and seat socket easily. Plug and play, IF the circuit works
yea I got one 45 min north of here and another 45 min south of here. I'll most likely hit one up and grab a few small things that I need.
 

Desync

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Apr 18, 2019
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I got this car for next to nothing. Traded a $500 Glock to my boss's cousin at work for the car. So I'm just tinkering with it and seeing if I can make it run smooth and slowly just mess around with it. Give me and my son something to do.
 
OHHHH so dirty. I love it.

do you know what direction you will be going with the car? Keeping it stock? Building it out?

to fix that Wheel Barrel look in the back on the tires you have 2 choices. Wheel spacers (ebay) or offset wheels.

The red car in my signature is my current project. The Engine I am getting is to do a split port swap. I decided to get the 04 doner and just tear it completely down then rebuild it.

Here is a link to a split port swap article, check it out and see if that may be a viable option for your car in the future.

https://forums.tccoa.com/9-engine-3-8l-4-2l/141039-s4gunns-3-8l-single-port-splitport-diy.html
 

Desync

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Apr 18, 2019
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Also last questions "FOR NOW" is what are these wires / connectors for?

One is a purple / yellow wire and a black wire. They are cut.

Second is this weird connector with 2 nipples coming out each end.

And last is a rubber hose that's been cut and it runs down to a round solenoid looking thing with a wire plugged into it.
 

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Desync

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Apr 18, 2019
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OHHHH so dirty. I love it.

do you know what direction you will be going with the car? Keeping it stock? Building it out?

to fix that Wheel Barrel look in the back on the tires you have 2 choices. Wheel spacers (ebay) or offset wheels.

The red car in my signature is my current project. The Engine I am getting is to do a split port swap. I decided to get the 04 doner and just tear it completely down then rebuild it.

Here is a link to a split port swap article, check it out and see if that may be a viable option for your car in the future.

https://forums.tccoa.com/9-engine-3-8l-4-2l/141039-s4gunns-3-8l-single-port-splitport-diy.html
Oh I'll def. be building on it, stock doesn't cut it for me. I come from the ricer generation when Fast and Furious just came out a month after I graduated high school. I had a '95 Nissan 240 SX SE. I pimped it out, then after I got my first job my dad co-signed with me a 2003 Eclipse I totally pimped out. So I'll def. be investing money into the stang on performance parts.

Already ordered a SR Cold Air Intake for it from AmericanMuscle.
 

Desync

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Apr 18, 2019
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I get those 3 items fixed, the last thing that I worry about is the fan, it's got the fan wires cut and they ran a on/off switch under the dash. So I have to make sure I turn the fan on when I crank the car up and turn the fan off when I cut the car off. So if I can get that fan working again, I'll be set. The old fan wires are still there under the hood, I just have no idea why they was cut and put on a toggle switch. The guy I got it from at work traded another vehicle for it so he doesn't have much information.


EDIT: I figured out the first 2 photos, it's vacuum hoses. So that's all good, last 2 things that I know is wrong. That purple/yellow wire and the fan.
 
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Also last questions "FOR NOW" is what are these wires / connectors for?

One is a purple / yellow wire and a black wire. They are cut.

Second is this weird connector with 2 nipples coming out each end

And last is a rubber hose that's been cut and it runs down to a round solenoid looking thing with a wire plugged into it.



The rubber hose that has been cut and runs to the solenoid, I don't know what it is but I found where it runs to. And I need to replace mine, thank you for that LOL. You can see the Autozone part number that you need for the hose
20190420_173210.jpg



20190420_174427.jpg
:oops:
Follow the thing red wire down to the duct tape, look left along that hard line, that is where it connects.
 
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Desync

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Apr 18, 2019
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The rubber hose that has been cut and runs to the solenoid, I don't know what it is but I found where it runs to. And I need to replace mine, thank you for that LOL. You can see the Autozone part number that you need for the hose
20190420_173210.jpg



20190420_174427.jpg
:oops:
Follow the thing red wire down to the duct tape, look left along that hard line, that is where it connects.

Appreciate it, that's going to be the vacuum lines then. Mine looks just like yours and when I turn the car on and hook them up, the hose collapses. So I need a new one also, as my heater / AC only blows on the windshield, it won't come out the vents.