Unsolvable: CS-144 Alternator charges and then stops working (1 Viewer)

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Friends:

I've reviewed threads extensively on how to install and solve issues with the installation of the CS-144 GM Alternator (A/C Delco version and Duralast version) in a 1984 FJ60, but I am at my witt's end. I've been trying to solve a recurring alternator charging problem for about 6 months -- at first the alternator works and charges. Then, one day, it stops. This has occurred on at least 4 replacement alternators. Clearly, there is a user error here. That would be me.

Why I installed this beefed-up alternator:

The existing Toyota alternator (55 amps) could not keep up with the upgraded electric on my truck -- Holley Sniper EFI (courtesy of Mosley Motors), a DUI distributor (courtesy Voodoo Cruisers when I purchased a wonderfully rebuilt 2F), dual Derale electric fans (at Summit), fog lamps, etc. The CS-144 seemed like the best solution because of part availability for the long term, 140 amps of power, and other IH8Mudders had successfully installed them.

Nature and symptoms of the problem:

After solving some alignment problems of the belt that goes around the alternator, a Saginaw power steering pump (no more incessant leaking from the Toyota model), and the harmonic balancer, I was certain I had good reliable belt traction. More importantly, I wanted to make sure there wasn't too much uneven pressure on alternator shaft. My AGM battery is never fully discharged and never starts lower than about 10 to 11 amps of charge. It is my understanding that installing an alternator on a fully discharge battery can damage the alternator. In most cases, the truck starts the alternator gauge reads right at about 12 amps (and the electronic Sniper monitor digitally reports about the same number of amps). Fairly quickly, the alternator will activate and I can see the charge gauge jump up to 13 to 14 amps, which indicates the alternator is charging the battery. The alternator runs very warm, but I assumed this was normal. Days or weeks will go by and then -- one day -- I will start the truck and the alternator does not charge and I watch the amp gauges slowly dwindle and confirm that charging is not occurring. I have no idea what is going on. Again, this has happened with at least 4 alternators (new and rebuilt).

How the alternator is installed and what I have attempted to trouble shoot:

Wiring.
The Toyota plug has two wires, but the GM alternator plug has four wires. It is my understanding only two wires are used from the GM plug, which has PLFS wires. The S wire (the large red one) connects directly to the BAT stud on the back of the alternator. A new heavy 2 gauge wire then runs from the BAT stud (through a circuit breaker, 150 amps) to the positive pole on the battery. I upgraded this wire to the battery to accommodate the great amp alternator. The L wire goes to the Toyota charge indicator wire.

GM plug for CS-144 alternator.jpeg
Havy.jpeg

Charge lamp relay. I thought my problem might be a charge lamp relay. But, I replaced it with another. Same symptoms occur.

fj 60 charge lamp relay 27790-13010.jpeg


Charge lamp in instrument cluster. Possible problem here. I have made certain the incandescent bulb is good and also used dialectic grease to make sure there is a good connection. My charge light never lights up at start-up or at any time.

Fuses.
All the fuses in the fuse box are good and properly sized.

Wiring harness. I recently installed a newer wiring harness from another FJ60. Mine had a short in it and fraying, so I wanted to make sure that it was solid and reliable.

WHAT AM I MISSNG? Thank you for your suggestions and comments, Roger
 
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I don't know the alternator but I was curious and the first result on my google search was this:

1595442880088.png
 

OSS

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I think you mean Volts instead of Amps in your description above.
Does the GM alternator have an internal voltage regulator?
 
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I think you mean Volts instead of Amps in your description above.
Does the GM alternator have an internal voltage regulator?
Yes sir, the alternator has an internal voltage regulator. Yes, thanks for that correction.
I think you mean Volts instead of Amps in your description above.
Does the GM alternator have an internal voltage regulator?
 
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I also tried googling "CS-144 charge issues" and there were a number of threads talking about adding a 100 ohm resistor to the charge light circuit. You might want to look into that too
 

OSS

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Have the returned alternators just been swapped with new ones, no questions asked?
I think the answer to the dead alternators lies inside the dead alternator. It should be tested to find out what went wrong -- (burnt diodes, fried regulator) instead of swapping in another unit again.
 
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Have the returned alternators just been swapped with new ones, no questions asked?
I think the answer to the dead alternators lies inside the dead alternator. It should be tested to find out what went wrong -- (burnt diodes, fried regulator) instead of swapping in another unit again.
Excellent idea. I have a nice dead alternator to have checked. Would an autozone be able to tell you what’s wrong, or do I need to take to a specialist? To answer your question, I have asked for an alternator to be tested and I was just told — “ya, that’s a bad one”
 
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No, that battery charge light is not on. It never lights up.

Given its not a normal alternator install its hard to say...but in stock form the charge light is the circuit that energizes the field. Without that light the alternator wont charge at idle but should self excite around 3000 rpm.
 
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Given its not a normal alternator install its hard to say...but in stock form the charge light is the circuit that energizes the field. Without that light the alternator wont charge at idle but should self excite around 3000 rpm.

Agreed. The fact that the battery light does not illuminate seems to be one of the few places to return to. That’s why I thought the charge light relay might be problematic. So I replaced it. And checked the light bulb itself. It is ok and just tried a new one. Is it possible that the actual circuit board on the back side of the gauges is faulty?

What I am thinking is happening — but who knows — is that when I install a new alternator — it works fine and kicks on at 3000 rpms. But, after exciting, there is no signal to turn the alternator off when a proper charge is reached. (That’s how they work?) So the alternator runs continuously and possibly burns itself out.

Again, I have no idea. It’s really frustrating because I’ve been successful installing the rebuilt engine, transmission, sniper and distributor myself, but I can’t figure this out.

Seth, thanks for the ideas! Very appreciated to have another person thinking about it.
 
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I would create a situation with a separate light bulb to get your charge light to come on (and go out) as it should. I would temporarily bypass the Toyota dash light relay and bulb. I rewired a 6v Ford tractor and used a light bulb to excite the alternator into charging.

Some diagrams and ideas here, although using the GM 10-si alternator:


I installed a GM 1-wire alternator on my '65 FJ45 (with an '83 2F engine) and it was super simple, had 85 amps of current, and was (of course) incredibly easy to wire. If you get desperate, that might be an option.
 

OSS

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you've mentioned the AGM battery gets to 10-11 volts. Even when cranking the starter it shouldn't drop that low.
If the battery is toast, it'll overwork the alternator (and maybe burn it up after a period of time).

To verify if the battery is ok enough, charge it fully on a wall charger then turn on the headlights with engine off and charger disconnected . They should shine brightly for 10 minutes at least. Check the voltage at the battery terminals with a voltmeter to monitor what's happening
 
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I would create a situation with a separate light bulb to get your charge light to come on (and go out) as it should. I would temporarily bypass the Toyota dash light relay and bulb. I rewired a 6v Ford tractor and used a light bulb to excite the alternator into charging.

Some diagrams and ideas here, although using the GM 10-si alternator:


I installed a GM 1-wire alternator on my '65 FJ45 (with an '83 2F engine) and it was super simple, had 85 amps of current, and was (of course) incredibly easy to wire. If you get desperate, that might be an option.

Saint Steven (fyi, I am professor of medieval history, so this is the highest form of compliment):

Fantastic approach to a work around and to solve the immediate problem. I'll do that!
 
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you've mentioned the AGM battery gets to 10-11 volts. Even when cranking the starter it shouldn't drop that low.
If the battery is toast, it'll overwork the alternator (and maybe burn it up after a period of time).
The battery will charge up properly to 12 volts. I never let it get below 10 volts. The battery is about three years old and I had it tested about 3 months ago and it was good. It could be failing, so I'll get it checked too. Thanks!
 
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A healthy battery should read 12.6 volts when the engine is off and shouldn't drop below 9.6 volts when cranking. While running you should see between 12.8v and 14.4 volts if things are charging properly.

The "Battery" light circuit should illuminate the battery light when the key is on but the truck isnt running. Once the truck starts the light should turn off and stay off. This circuit sends 12v through the bulb to the field exciter terminal on the alternator. The circuit grounds through the alternator but once the truck starts an the alternator starts producting voltage the ground path is eliminated by the voltage being produced and the light can no longer stay on. Once the alternator starts producing voltage the voltage regulator (internal or external depending on design) is what will control the amount of voltage being produced. The battery light/exciter circuit is only used on start up.
 

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The battery will charge up properly to 12 volts. I never let it get below 10 volts. The battery is about three years old and I had it tested about 3 months ago and it was good. It could be failing, so I'll get it checked too. Thanks!


curious ?

you mention up top the original 55 amp alternator could not keep up with your system

did you have that one tested prior to the install of the GM one

perhaps the OEM one was simply bad or going bad and dying on you in the beginning


just a alternative point of view not brought up yet ?


if you still have it a solid diagnosis on it could help solve this issue 100%

\
matt
 

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