Here We Go Again Low Voltage M1009

[jplace1011]

I feel like I’m just running around in circles here with my M1009!

When I picked up my vehicle, to fix an oil leak, the mechanic said he had to charge the two batteries overnight. All because it won’t start. I decided to test the batteries today and here’s what I got:

Off
Front 12.53
Rear 12.53

Off After a Short Drive & One Restart
Front 13
Rear 12.76


Running
Front 14.30
Rear 13.07

Running After a Short Drive & One Start
Front 14.40
Rear 12.80

The Rear Battery seems to be low. The Voltage Meter looks Low as well.

Note: The mechanic recharged the batteries and I had him Replace the Passengers Side Alternator. Alternator is from Hillbilly Wizard. The other alternator, Drivers side, was replaced just last year as well.

Today I also went around and made sure no cables or plugs were undone or loose on the Alternator and each battery. Both batteries were installed Dec. 2020. The Gen 1 & 2 Bulbs in the dash are turning on as well. I think the Alt belt is tight enough?

So what could be going on now?

Thank you for any help.


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[Keith_J]

Do you have a multimeter? Know how to use it? See the sticky thread at the top on testing alternator in vehicle.

 

[Squibbly]

When I picked up my vehicle, to fix an oil leak...

What ended up being the cause of the oil leak?

 

[jplace1011]

What ended up being the cause of the oil leak?

Hey @Squibbly buddy! I’m still waiting to hear back from my Dad’s buddy, for him to look at it. He did mention checking the Oil Pan Gasket. I will let you know though.

It seems to just be one thing after another! I did the math of parts and labor I’ve spent over the last two years. I literally could have bought another CUCV!!


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[jplace1011]

Hey @Squibbly buddy! I’m still waiting to hear back from my Dad’s buddy, for him to look at it. He did mention checking the Oil Pan Gasket. I will let you know though.

It seems to just be one thing after another! I did the math of parts and labor I’ve spent over the last two years. I literally could have bought another CUCV!!


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@Keith_J I do have a Multimeter. I’m not real keen to it, but I’ll see about finding the thread you mentioned.


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[nyoffroad]

Hey @Squibbly buddy! I’m still waiting to hear back from my Dad’s buddy, for him to look at it. He did mention checking the Oil Pan Gasket. I will let you know though.

It seems to just be one thing after another! I did the math of parts and labor I’ve spent over the last two years. I literally could have bought another CUCV!!


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Older vehicles always require more Maintenace and repair and if can't or won't do the only other alternative is pay someone else to do it (as you well know). Think about all the cash you could save by learning even just basic stuff like trouble shooting the charging system and rebuilding the alternators yourself. All it takes is some basic hand tools and the will to learn (and this forum). Try it!

 

[jplace1011]

Older vehicles always require more Maintenace and repair and if can't or won't do the only other alternative is pay someone else to do it (as you well know). Think about all the cash you could save by learning even just basic stuff like trouble shooting the charging system and rebuilding the alternators yourself. All it takes is some basic hand tools and the will to learn (and this forum). Try it!

I took a look at the Charts in the TM. I wanted to trace the wires & Cables for the batteries and for the alternators. I took a look at the Junction Blocks, I’m not entirely sure that’s the name. The Positive and Negative Blocks behind the batteries, where all of the cables connect to.

I’m wondering could this frayed cable that goes to both of them be the problem? It’s the Black Cable with a White Tag/Sticker wrapped around it. It sure looks like it got fryed, you can see the burn marks on the post/bolt.

I’m not sure what it does exactly, I’ll have to look in the TM. Still could this be the problem?

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[Mullaney]

I took a look at the Charts in the TM. I wanted to trace the wires & Cables for the batteries and for the alternators. I took a look at the Junction Blocks, I’m not entirely sure that’s the name. The Positive and Negative Blocks behind the batteries, where all of the cables connect to.

I’m wondering could this frayed cable that goes to both of them be the problem? It’s the Black Cable with a White Tag/Sticker wrapped around it. It sure looks like it got fryed, you can see the burn marks on the post/bolt.

I’m not sure what it does exactly, I’ll have to look in the TM. Still could this be the problem?

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.
Is that "white fuzzy looking" stuff on the contacts oxidation? If it is, some cleaning and anti-oxidation paste on the connections would help for sure. If you aren't getting good "contact" between the post and the terminal - that will definitely cause performance and reliability problems.

 

[jplace1011]

.
Is that "white fuzzy looking" stuff on the contacts oxidation? If it is, some cleaning and anti-oxidation paste on the connections would help for sure. If you aren't getting good "contact" between the post and the terminal - that will definitely cause performance and reliability problems.

I cleaned the posts on the top block (positive) not long ago. However, I don’t think I cleaned the bottom posts (negative).

I’ll go ahead and clean the bottom posts and apply anti-oxidation paste. Is that the same stuff that’s is a small square tube that you can put on car light bulbs? I’ll replace that fried cable as well. I just don’t know what it does and what it called/part number?? Is it a Capacitor?


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[Mullaney]

I cleaned the posts on the top block (positive) not long ago. However, I don’t think I cleaned the bottom posts (negative).

I’ll go ahead and clean the bottom posts and apply anti-oxidation paste. Is that the same stuff that’s is a small square tube that you can put on car light bulbs? I’ll replace that fried cable as well. I just don’t know what it does and what it called/part number??


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.
Yes Sir. Same stuff.
Here it is in bulk.
Picture below:



This isn't necessarily the best or worst but it has worked well for me for a lot of years. You can find it easily online with a quick search by name.

 

[Keith_J]

That fried component is a radio frequency suppression capacitor set. Not needed for function.

With key on engine off, you should measure around 12 volts from the negative terminal of the alternator to both regulator connections on the plastic 2 wire connector that plugs into the alternator.

This connector has a wire from the dash light for the alternator and one wire from the battery the alternator charges.

I built a test rig with a replacement connector, a small lamp and wire. I plug it into a suspect alternator, then connect this test rig to the battery with engine running. If voltage jumps, it is an external wiring problem. If no voltage change, the alternator gets rebuilt

 

[jplace1011]

That fried component is a radio frequency suppression capacitor set. Not needed for function.

With key on engine off, you should measure around 12 volts from the negative terminal of the alternator to both regulator connections on the plastic 2 wire connector that plugs into the alternator.

This connector has a wire from the dash light for the alternator and one wire from the battery the alternator charges.

I built a test rig with a replacement connector, a small lamp and wire. I plug it into a suspect alternator, then connect this test rig to the battery with engine running. If voltage jumps, it is an external wiring problem. If no voltage change, the alternator gets rebuilt

@Keith_J glad I don’t have to worry about that Capacitor.

Where exactly is the Neg. Terminal of the Alternator?

The Regulator Connections, you mean the Two Wires (Red & Brown) that connect to the plug that plugs into the back of the alternator right?

I covered the Brown Wire with electrical tape a ways back. Does the Brown Wire go back to the Battery? That might be something for me to inspect. I’ll take the tape off and see how the wire looks. Hmmmm…


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[Keith_J]

Yes, the two wire block going into a 27SI side is connected to the regulator. Red wire goes to the battery the alternator charges and is protected by a fusible link. The brown wire is the dash light, if it illuminates, it means the alternator has no output. Labeled terminal 1 in manuals.
The red wire is the sense line, this is how the regulator determines battery charge. This is labeled terminal 2 in the manuals.

With key on, engine off, current flows through the single 24 volt fuse on the fuse panel, bottom center. This current illuminates the dash lights for each alternator since the alternators cannot generate any current through the diode trio in the alternator. This is a tiny current which attempts to magnetize the rotor through the regulator.

With engine on, the dash light current creates the bootstrap magnetic field in the rotor, now turning, which generates a small voltage in the stator windings. This is tapped by the diode trio which feeds internally to regulator terminal 1. Voltage builds to around 14, this causes the dash light to go out. Some regulators need a blip on the throttle to fully bootstrap. Also caused by weak dash light bulb.

This is why voltage is required at both regulator terminals.

 

[jplace1011]

@Keith_J glad I don’t have to worry about that Capacitor.

Where exactly is the Neg. Terminal of the Alternator?

The Regulator Connections, you mean the Two Wires (Red & Brown) that connect to the plug that plugs into the back of the alternator right?

I covered the Brown Wire with electrical tape a ways back. Does the Brown Wire go back to the Battery? That might be something for me to inspect. I’ll take the tape off and see how the wire looks. Hmmmm…


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@Keith_J

Here’s a pic of the Brown Wire. It isn’t terrible, but I will end up cutting the wire and crimping it.

I was also able to figure out what is what on the back of the alternator. It’s actually written on there. Imagine that!!

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[Keith_J]

Careful, that red with white stripe 8mm wire has 12.5 volts on it at all times. It is connected to the negative terminal of the back battery..which is also connected to the positive terminal of the front battery.

 

[jplace1011]

Careful, that red with white stripe 8mm wire has 12.5 volts on it at all times. It is connected to the negative terminal of the back battery..which is also connected to the positive terminal of the front battery.

I’ll disconnect both batteries before I do anything. I should be good right?

I was thinking, the mechanic said he had to recharge the batteries. I then gave him the new alternator and the rear battery still is low. So does that mean the problem may not be the alternator? Something seemed wrong before the switching and still after the switching of alternators. Just a thought.


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[Keith_J]

Could be an open fusible link. Either the 8mm red with white (back battery negative, should be 12.5 volts to ground), the regulator sense wire (should be 24+ volts to ground) or the 8mm red wire to the 24 volt bus (again, 24 volts).

Measure voltage with batteries connected.

Driver side alternator testing is similar, only the negative goes to ground and the other wires test to 12.5 volts.

 

[jplace1011]

Could be an open fusible link. Either the 8mm red with white (back battery negative, should be 12.5 volts to ground), the regulator sense wire (should be 24+ volts to ground) or the 8mm red wire to the 24 volt bus (again, 24 volts).

Measure voltage with batteries connected.

Driver side alternator testing is similar, only the negative goes to ground and the other wires test to 12.5 volts.

Not that long ago I had the Negative Cable for the Front Battery Replaced. The mechanic mentioned the Bolt for the Negative Bus Bar is stripped, you can see in the pic below.

I’m wondering if this could have anything to do with my recent issues? Perhaps the connection is not very good. Maybe I should replace this Bolt while I’m cleaning all of the Negative Bus Terminal. Is it difficult to change the bolts out?


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[Keith_J]

If the connection is tight, leave it be.

You mentioned you have a multimeter. Set it for Voltage DC and test the wires to the regulator, key on engine off. Should be front battery voltage for the drivers side alternator with the multimeter negative lead connected to ground. For passenger alternator, these will be the combined voltage of front and rear batteries.

The Batt + terminal of drivers side alternator should be front battery voltage. The Batt - terminal will connect to ground, no fusible link here.

The passenger side alternator Batt - should measure front battery voltage, Batt + will be combined battery voltage. Both measured to ground.

If any circuit doesn't show voltage, you need to locate its fusible link, usually nearest firewall connection. Feel it for any swelled section or break. NAPA has this wire and crimp connections.

If key on engine off voltages are correct, the problem is in the alternator. If voltage on the passenger side alternator connections are missing on the red wire, it could be the relay under the dash.

 

[ezgn]

Not that long ago I had the Negative Cable for the Front Battery Replaced. The mechanic mentioned the Bolt for the Negative Bus Bar is stripped, you can see in the pic below.

I’m wondering if this could have anything to do with my recent issues? Perhaps the connection is not very good. Maybe I should replace this Bolt while I’m cleaning all of the Negative Bus Terminal. Is it difficult to change the bolts out?


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Anything electrical needs to be done 100% correctly. There is no room for good enough when it comes to electrical. Your cables are the most important part of your system. If it is stripped then of course it has to be fixed. If you are working on anything electrical, disconnect the batteries so you stay safe. A loose connection can potentially destroy a lot of wiring and possibly burn down your vehicle.