Own a 1970 FJ40 need to replace the alternator to more AMPS what you guys recommend and what mods need to do for that upgrade
Alternator upgrade (1 Viewer)
- Thread starter 4LABAJA
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I believe I used a 1992 Dodge Monaco alternator from rock auto. Not too hard to make it fit. I think you have to bypass the ammeter though in the cluster.
How much more amperage do you need? My original 1970/71 alternator (40amps) crapped out the other day, so I went ahead and purchased a refurbished 1974 Toyota Celica alternator rated at 55amps. The part is interchangeable with the fj40 as it has the same part number. For some reason, however, the 55 amp alternator never seemed to make it onto the US Fj40 market...??? Although, It is listed in the parts catalog for an Fj40. Hmm 
If you plan on getting rid of your alternator and if it's still in working condition, I would be interested in buying it from you.
If you plan on getting rid of your alternator and if it's still in working condition, I would be interested in buying it from you.
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Would like to get a 100 amp at least cause so many accessories ARB compressor for airlockers, elecrical fan, off road led lights, radio, VHF Radio, GPs Lowrance, gauges, and future modsHow much more amperage do you need? My original 1970/71 alternator (40amps) crapped out the other day, so I went ahead and purchased a refurbished 1974 Toyota Celica alternator rated at 55amps. The part is interchangeable with the fj40 as it has the same part number. For some reason, however, the 55 amp alternator never seemed to make it onto the US Fj40 market...??? Although, It is listed in the parts catalog for an Fj40. Hmm
If you plan on getting rid of your alternator and if it's still in working condition, I would be interested in buying it from you.
Below is the write up I did on my 75’.
The GM alternator conversion has been a great update for me! The 4 AWG wire directly to the battery really helps when charging under load while using the winch, lights and so on. I've melted the leads to the factory alternator before which may or may not charge the battery fully after 15 minutes of run time. This is the alternator mount that I used that bolted right up with very minimal grinding on the bottom mount.
Alternator from a 1995/96 Caddy Fleetweed Broughnom is what I started with. Thats a CS144 case, with the 12 and 6 mounting locations. If your current pulley won't line up on the new alternator, order a power master pulley to help alignment. I believe I went to Orileys for the alternator. They sell the pigtail there as well. That makes it very easy to wire up.
You need a 4 AWG wire with ring terminals to go from the positive post of the alternator to the positive post of the battery. There is a plug with four wires, starting with the big wire (it has the larger of the four pins) they are:
S - connect this right to the "+" stud on the alternator with a ring terminal (big wire)
F - Not needed
L - Connect to 12V key on source at the fuse panel
P - Not used
The fuse panel has blade terminals on the back of it to hook up the 12v key on source. DO NOT USE THE AMP GAUGE, it may melt or catch fire, you'll have to pull out the cluster, disconnect the amp gauge and wire the two amp gauge wires together to complete the circuit. Then you'll need to disconnect the factory external regulator. That's it! Two wires with the third being the 4AWG to the battery. Very easy set up.
Some may say you need to wire in a 12v light to the 12v key on wire but you don't need it. Some threads may mention to wire up an alternator light, that's unnecessary too. If anything, wire up a digital volt gauge or buy a volt gauge that you can plug into the cig lighter if you ever have any questions as to weather the the vehicle is charging.
The GM alternator conversion has been a great update for me! The 4 AWG wire directly to the battery really helps when charging under load while using the winch, lights and so on. I've melted the leads to the factory alternator before which may or may not charge the battery fully after 15 minutes of run time. This is the alternator mount that I used that bolted right up with very minimal grinding on the bottom mount.
Alternator from a 1995/96 Caddy Fleetweed Broughnom is what I started with. Thats a CS144 case, with the 12 and 6 mounting locations. If your current pulley won't line up on the new alternator, order a power master pulley to help alignment. I believe I went to Orileys for the alternator. They sell the pigtail there as well. That makes it very easy to wire up.
You need a 4 AWG wire with ring terminals to go from the positive post of the alternator to the positive post of the battery. There is a plug with four wires, starting with the big wire (it has the larger of the four pins) they are:
S - connect this right to the "+" stud on the alternator with a ring terminal (big wire)
F - Not needed
L - Connect to 12V key on source at the fuse panel
P - Not used
The fuse panel has blade terminals on the back of it to hook up the 12v key on source. DO NOT USE THE AMP GAUGE, it may melt or catch fire, you'll have to pull out the cluster, disconnect the amp gauge and wire the two amp gauge wires together to complete the circuit. Then you'll need to disconnect the factory external regulator. That's it! Two wires with the third being the 4AWG to the battery. Very easy set up.
Some may say you need to wire in a 12v light to the 12v key on wire but you don't need it. Some threads may mention to wire up an alternator light, that's unnecessary too. If anything, wire up a digital volt gauge or buy a volt gauge that you can plug into the cig lighter if you ever have any questions as to weather the the vehicle is charging.
I'm one of those people that say you do need to wire a 50 ohm 5 watt resistor on the " L " line ( or a light bulb) to avoid burning out the internal regulator. The regulator will survive for a while without the resistance on the " L " but eventually it will fail. The only CS style alternators that don't need that (to my knowledge) are the ones that have a plug socket with a terminal labeled " I " rather than " F " . If you have the I terminal, then the ignition switched wire goes to it rather than the L and it would not need the light bulb or resistor inline. Just passing along hard earned experience.
I
I had never read this being the reason needing the small draw of the resistor or the bulb. I always thought that you needed it in order for the alternator to excite. Looks like I’ll be putting one in line now. Thanks!
I had never read this being the reason needing the small draw of the resistor or the bulb. I always thought that you needed it in order for the alternator to excite. Looks like I’ll be putting one in line now. Thanks!
Coolerman
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I would also add that instead of hooking the S terminal wire to B+ at the alternator that you hook it up so that it is measuring the voltage at the fuse block. Why? The voltage at the fuse block will be lower than the voltage measured at the output of the alternator or at the battery due to wire resistance and electrical load. You want the S terminal connected here so that the alternator will raise the voltage to compensate for that. This results in a better charge for the battery AND brighter lights all around.
For your 1970 a very easy way to do this without having to run a new wire is to use the old screw terminal voltage regulator as a terminal strip. First cut the three terminal alternator connector off at the alternator. You will be left with a White/Green and a White/Black wire. Ground the White/Black wire to the case of the alternator or tape it off. Connect the White/Green to the S terminal of the GM alternator. Go to the voltage regulator and move the White/Green wire (which runs to the alternator) and put it on top of the White/Red wire going into the voltage regulator which comes straight from the fuse block. Now the alternator will sense the voltage level at the fuse block.
If you have a regulator with the three pin connector instead of the screw terminals: Unplug the regulator from the wiring harness. Plug in a cheap simple adapter I make that jumpers the White/Red to the White/Green. Easy peasy!
For your 1970 a very easy way to do this without having to run a new wire is to use the old screw terminal voltage regulator as a terminal strip. First cut the three terminal alternator connector off at the alternator. You will be left with a White/Green and a White/Black wire. Ground the White/Black wire to the case of the alternator or tape it off. Connect the White/Green to the S terminal of the GM alternator. Go to the voltage regulator and move the White/Green wire (which runs to the alternator) and put it on top of the White/Red wire going into the voltage regulator which comes straight from the fuse block. Now the alternator will sense the voltage level at the fuse block.
If you have a regulator with the three pin connector instead of the screw terminals: Unplug the regulator from the wiring harness. Plug in a cheap simple adapter I make that jumpers the White/Red to the White/Green. Easy peasy!
