77 FJ40 Alternator/Wiring Question

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I am a first time FJ owner and a novice mechanic at the very best, so appreciate any help! I replaced the battery and alternator and found that the alternator is not charging. In going through the wiring, I found that two wires from the headlight are connected to two alternator wires and are all consolidated into one wire (4 into 1 - see attached pic), which runs up into the pig tail connector to the alternator (with a second wire). The wires in the plug are registering 0 volts on the multimeter. The headlight works (so maybe the disconnect is at the plug to the alternator).

Any thoughts on where to go from here? Does anyone know where the headlight wires are supposed to be routed to free up the three single alternator wires? It seems there is probably still a short somewhere (maybe in the plug), as the plug is not registering on the multimeter at all, as is.

Any and all help is appreciated!

Gus
FJ40 Wiring.jpg
 

SouthBostonFJ40

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Those black and white wires are grounds. I wouldn't disconnect them unless you have a plan for replacing them.

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Thanks, Boston. So, it appears that all 4 wires that were consolidated into one are grounds. Would you leave this configuration? Also, I still have no volts at the plug to the alternator (where the 4-1 ground wire and the white/green wire connect). Any thoughts there? I was considering cutting the plug off and attaching the wires directly to the alternator, in case there is a bad connection in the plug itself.

The white/blue wire that connects directly to the alternator is reading 12.5 volts.
 

sggoat

 
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There should not be any wires from the alternator connected to the headlights. The head lights come off a 20 amp fuse in the fuse block through a red wire to the light control switch. The tail lights also come into this switch from the fuse block through a green wire with red stripe. See attached schematic-hope this helps--
scan0001.jpg
scan0002.jpg
scan0003.jpg
 

SouthBostonFJ40

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Thanks, Boston. So, it appears that all 4 wires that were consolidated into one are grounds. Would you leave this configuration? Also, I still have no volts at the plug to the alternator (where the 4-1 ground wire and the white/green wire connect). Any thoughts there? I was considering cutting the plug off and attaching the wires directly to the alternator, in case there is a bad connection in the plug itself.

The white/blue wire that connects directly to the alternator is reading 12.5 volts.
I am not a wiring expert, or even a novice for that matter. Coolerman or Pin_Head are the experts here for that. I do know that the grounds you show in your picture are stock and the only one I would do anything with is the one that went to the alternator. You can cut that off and retape the bundle. Then run a new ground from the alternator directly to the chassis.
 

DSRTRDR

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Toyota ran a ground circuit for several devices and switches around the truck - the white/black wires all connect, I would not disconnect them

do you have an externally or internally regulated alternator ? if externally regulated, do you know whether the voltage regulator is o.k. ?

what were your symptoms in the first place ?
 
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Toyota ran a ground circuit for several devices and switches around the truck - the white/black wires all connect, I would not disconnect them

do you have an externally or internally regulated alternator ? if externally regulated, do you know whether the voltage regulator is o.k. ?

what were your symptoms in the first place ?
Hi Claudia - the alternator is internally regulated. The symptoms started with the battery draining. I thought the new stereo might be drawing on it, but that did not appear to be the issue. The battery was getting up there in age, so I went ahead and put a new one in and it still drained. The alternator passed the bench test, but the bearing was rough, so I went ahead and put a new one in. With the new alternator in, I had the parts store run a draw test and it would not complete, as the alternator was not showing any power at all. That is when I started investigating the wiring. The multimeter on the plug into the alternator is not showing any volts at all.
 

bj40green

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Can you show a pic of how the wiring is connected on the new alternator?
The B lug has only output if the IGN (and / or S) terminal gets a switched (from the key) voltage.
The connector on the back side.... how many terminals are there and how are they marked?
Does it look like one of these or is it different?
What brand and model is your new alternator?
alternator_connections_002.jpg

Rudi
alternator_connections_002.jpg
 
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Can you show a pic of how the wiring is connected on the new alternator?
The B lug has only output if the IGN (and / or S) terminal gets a switched (from the key) voltage.
The connector on the back side.... how many terminals are there and how are they marked?
Does it look like one of these or is it different?
What brand and model is your new alternator?
View attachment 671064

Rudi
Hi Rudi,

Okay...so, hold the phone. I just realized that the alternator is externally regulated (WorldWide By Remy International Mfg#14540). I am attaching a photo of the terminals and markings. They are E on top, F bottom left and N bottom right. The white with green wire is positioned to affix to the F (Field) terminal. This is the same wire that is not reading any volts with the multimeter.

I am also attaching a couple photos of what I am guessing is the external regulator. Confirmation of this guess would be appreciated! The connection looks to have quite a bit of corrosion. I have not looked up how to test it (don't even know if that is what it is yet!) or whether replacement is the better idea at this stage.
 
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Hi Rudi,

Okay...so, hold the phone. I just realized that the alternator is externally regulated (WorldWide By Remy International Mfg#14540). I am attaching a photo of the terminals and markings. They are E on top, F bottom left and N bottom right. The white with green wire is positioned to affix to the F (Field) terminal. This is the same wire that is not reading any volts with the multimeter.

I am also attaching a couple photos of what I am guessing is the external regulator. Confirmation of this guess would be appreciated! The connection looks to have quite a bit of corrosion. I have not looked up how to test it (don't even know if that is what it is yet!) or whether replacement is the better idea at this stage.
The attachments never made it...here they are.
FJ40 AlternatorEFN.jpg
Regulator.jpg
Regulator2.jpg
 
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I want to take a quick moment and thank each and ever one of you for your assistance, thus far. In a society where we blow past those in need all the time, the fact that you are all helping those of us with no clue is truly refreshing!
 

DSRTRDR

I can mangle anything ...
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I am having some difficulty orienting myself on your pics, but the external regulator, in the original location, should be on the firewall - a rectangular box

I want to take a quick moment and thank each and every one of you for your assistance, thus far. In a society where we blow past those in need all the time, the fact that you are all helping those of us with no clue is truly refreshing!
I don't know exactly why, either (although I have some suspicion ;)), but apparently, we seem to enjoy arcane details here :rolleyes: :lol:
 
Last edited:

bj40green

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Hi Sundance,

Here is a pic with the connections.
The circuit is: Turn the key to the "on" position. There should be a voltage equal to the battery voltage on the IGN terminal. This is the input for the VR. Depending on how high this voltage is the output on the "F" terminal is equal to the IGN voltage. When the battery voltage is somewhere around 14.4V (depends on the set point of your VR) the voltage on the F terminal drops to +/- 7 Volts.
So.... if there is no voltage on the F terminal check for voltage on the IGN terminal. No voltage on the IGN terminal, check the fusebox and check the ENGINE fuse. Check fuse and the contact clamps for corrosion.
VR - Alt hook up DESTIN_edit.JPG

Hope this helps to figure out your problem,

Rudi
VR - Alt hook up DESTIN_edit.JPG
 
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I am having some difficulty orienting myself on your pics, but the external regulator, in the original location, should be on the firewall - a rectangular box



I don't know exactly why, either (although I have some suspicion ;)), but apparently, we seem to enjoy arcane details here :rolleyes: :lol:
Thanks Claudia,

The box in the pics is sitting underneath the battery, mounted on the wheel well of the passenger side. There are three wires running into it through a plug. Not sure if that would be the regulator or not. I will keep investigating.
 

DSRTRDR

I can mangle anything ...
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Thanks Claudia,

The box in the pics is sitting underneath the battery, mounted on the wheel well of the passenger side. There are three wires running into it through a plug. Not sure if that would be the regulator or not. I will keep investigating.
think that's something else - need pics of the firewall on the driver's side - the external voltage regulator, in OEM location, would be on the driver side firewall under the master brake cylinder
 

caladin

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Hi Sundance,

Here is a pic with the connections.
The circuit is: Turn the key to the "on" position. There should be a voltage equal to the battery voltage on the IGN terminal. This is the input for the VR. Depending on how high this voltage is the output on the "F" terminal is equal to the IGN voltage. When the battery voltage is somewhere around 14.4V (depends on the set point of your VR) the voltage on the F terminal drops to +/- 7 Volts.
So.... if there is no voltage on the F terminal check for voltage on the IGN terminal. No voltage on the IGN terminal, check the fusebox and check the ENGINE fuse. Check fuse and the contact clamps for corrosion.
View attachment 671370


Hope this helps to figure out your problem,

Rudi
Thanks, Rudi! I will get on this tomorrow. So...if the connector to the alternator does not have a wire in the "N" position or IGN on your diagram, then I do not have an external regulator, correct? Because, all I have going into the alternator is the Battery B, the Ground or E and the F wire. I will check the outputs in the morning and see what I get! Maybe I just need to come down to Costa Rica...been dying to get there.
 
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