I have a 1978 FJ40 and the charging system stopped working last night on the ride home. The headlights flicked bright then dim a few times and finally stayed dim. I just checked the charging output and my volt meter said 11.4 VDC. How do I tell if I need the $35 voltage regulator or the $200 alternator? Any help is greatly appreciated. TIA - Bob
How to identify if voltage regulator or alternator is bad? (14 Viewers)
- Thread starter 2wheelbob
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To test the alternator:
Put your volt meter on the B+ lug of the alternator.
Disconnect the plug at the back of the alternator.
Start the engine and rev it up to 1500 RPM.
Jump between the B+ lug and the F terminal (umplugged) with a wire or paper clip.
If the voltage rises above 13V, the alternator is good.
Remove jumper wire.
Put your volt meter on the B+ lug of the alternator.
Disconnect the plug at the back of the alternator.
Start the engine and rev it up to 1500 RPM.
Jump between the B+ lug and the F terminal (umplugged) with a wire or paper clip.
If the voltage rises above 13V, the alternator is good.
Remove jumper wire.
Make sure you have a good ground. Had a similar issue with a bad ground
Pin Head, are these instructions for an alternator with voltage regulator or for an alternator with integral regulator? I know that when I drove the '79 home from Quito that it must have been working as there is no way the battery would have held up for a ten hour drive. But I have swapped this motor and harness into my '70 FJ40. I have employed the 18" fusible link idea I found here on MUD, along with the two 5amp fuses, but I started the vehicle today and I don't see any movement on the ammeter. On the alternator there is a green plug that goes into the back of the "regulator" on the top of the alternator. This plug has provisions for two spade terminals, however, only one wire was on this. And frankly I don't remember if it was in the top or the bottom of the two options. Any advice would be welcome. I put the voltage meter on the two battery posts and of course it reads 12.56V. I'm thinking that while running it should register something like 14V.
AlaskanWheeler
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Hooking up with and oscilloscope would be the best method to determine the condition of your alternator and your regulator.
That is good advice, I shudder to think of what translation to Spanish that would be, let alone finding the equipment. But thanks!
bj40green
Tssss, tssss
Lenny, On any '79 and later with the 50-0-50 Ammeter the gauge doesn't function properly due to a design error. If you're lucky you'll see the needle twitch a bit when you turn the hazards on. There is a fix for that.
If your battery reads 12.56V (engine not running) that means that your battery is full. If it reads below 12V it needs recharging.
Please post a picture of your alternator with that wire.
Rudi
If your battery reads 12.56V (engine not running) that means that your battery is full. If it reads below 12V it needs recharging.
Please post a picture of your alternator with that wire.
Rudi
Amigo,
The test is for the externally regulated alternator, but the same test works for the internally regulated alternator too except the terminal is marked I and the test won't tell if the regulator or alternator is bad, which doesn't matter because they are one replaceable unit.
The test is for the externally regulated alternator, but the same test works for the internally regulated alternator too except the terminal is marked I and the test won't tell if the regulator or alternator is bad, which doesn't matter because they are one replaceable unit.
I need to take a picture tomorrow of the plug for you and BJ40 Green (Rudi). I was thinking about what I checked today. I just touched my multi-tester leads to the positive and negative terminals, at the attached leads on the clamp. Seems that would just check the battery. Should I instead touch the WB wire terminal on the alternator and to a good ground to check the voltage to see if the alternator is putting out?
It really doesn't matter where you measure. If the voltage rises 0.5 V or more when the engine is running, the alternator is putting out juice. Jumping the hot wire at the alternator just removes potential problems with the upstream circuits.
Thanks Pin Head, I'm going to try that tomorrow. I also need to make sure that the rpm's are elevated, maybe around 2,000 to assure that it is spinning fast enough.
It started up good this morning, that is a good indication that nothing is pulling on the battery. I checked the battery before doing anything and it read 12.75V. I started it and after letting it run a bit I pulled the choke on a little to elevate rpm and checked the BW wire at the alternator to engine block ground and got 14.45V so I think it is good. The other pictures show what I have been faced with throughout retrofitting this '79 harness to the '70. Twisted/taped wiring and just a mess. I think the last picture shows the "new" radio connection stuff. Oh, in the second photo showing the fuse box for the two 5A fuses for the ammeter you can see a piece of the yellow 14 gauge wire that is 18" long for the fusible link.
Then a new, certainly for me, issue developed. The motor was idling very smooth, I had the radiator cap off to top off the coolant and let it burp, which it didn't as I guess it had burped during the running yesterday. So I put the cap back on as I wanted to see if that would move the temperature gauge, maybe it needs to run longer, not sure, but it wasn't moving off of zero. So then I turned off the key and nothing happened. Motor continued to run just a smooth as could be. I pulled the negative cable, that had no effect so I grabbed a pair of insulated pliers and pulled the coil wire out of the coil. That worked. A little research and I found this (keep in mind that this is a Toyota harness and not an American Autowire harness which is now in the '79);
"This can be caused by a few different things.The first item to check would be the alternator. There may be a feedback to the ignition switch from the voltage regulator field exciter wire. The other scenario that we commonly see is feedback from an aftermarket ignition system that utilizes an internal relay, or both a battery and ignition source to power the system. These are fairly common problems that people experience when using many aftermarket-wiring systems. Generally, an OEM harness will not have the problem of alternator “run-on”, as there is usually a resistance wire in the dash harness to keep this from happening.
Solution: To figure out where the problem exists, start the car and with the key in the ON position and the car running, turn off the key. With the ignition turned off and the car continuing to run, simply remove the plug from the alternator (DO NOT TRY AND REMOVE THE BATTERY POWER WIRE FROM THE POWER STUD!) and the car should shut off if the alternator is creating the problem. If it does not stop running, your feedback problem is coming from something other that the alternator. If you are using an aftermarket ignition unit, check to see if there is a fix available that includes a diode to put in line on the ignition feed to keep their system from back feeding into the ignition switch. If you do not have an aftermarket ignition system in your car and it continues to run after pulling the alternator plug, you’ll want to call tech support from your harness manufacturer for help. If your car does shut off when you remove your alternator plug, you may have to put a diode in line on the field exciter wire to keep the alternator from back feeding to the ignition switch. Again check with the harness manufacturer for help." I do have a diode and holder that I could use. I had bought this on suggestion from American Autowire as my starter didn't have the extra lug for the cold weather bypass of the ballast. The unit is nice, except that you can't close the cover once the diode is installed. So I don't have cold weather down here so it just sits in the electric box. But I could use it if that is the problem. Where would I install it?
Then a new, certainly for me, issue developed. The motor was idling very smooth, I had the radiator cap off to top off the coolant and let it burp, which it didn't as I guess it had burped during the running yesterday. So I put the cap back on as I wanted to see if that would move the temperature gauge, maybe it needs to run longer, not sure, but it wasn't moving off of zero. So then I turned off the key and nothing happened. Motor continued to run just a smooth as could be. I pulled the negative cable, that had no effect so I grabbed a pair of insulated pliers and pulled the coil wire out of the coil. That worked. A little research and I found this (keep in mind that this is a Toyota harness and not an American Autowire harness which is now in the '79);
"This can be caused by a few different things.The first item to check would be the alternator. There may be a feedback to the ignition switch from the voltage regulator field exciter wire. The other scenario that we commonly see is feedback from an aftermarket ignition system that utilizes an internal relay, or both a battery and ignition source to power the system. These are fairly common problems that people experience when using many aftermarket-wiring systems. Generally, an OEM harness will not have the problem of alternator “run-on”, as there is usually a resistance wire in the dash harness to keep this from happening.
Solution: To figure out where the problem exists, start the car and with the key in the ON position and the car running, turn off the key. With the ignition turned off and the car continuing to run, simply remove the plug from the alternator (DO NOT TRY AND REMOVE THE BATTERY POWER WIRE FROM THE POWER STUD!) and the car should shut off if the alternator is creating the problem. If it does not stop running, your feedback problem is coming from something other that the alternator. If you are using an aftermarket ignition unit, check to see if there is a fix available that includes a diode to put in line on the ignition feed to keep their system from back feeding into the ignition switch. If you do not have an aftermarket ignition system in your car and it continues to run after pulling the alternator plug, you’ll want to call tech support from your harness manufacturer for help. If your car does shut off when you remove your alternator plug, you may have to put a diode in line on the field exciter wire to keep the alternator from back feeding to the ignition switch. Again check with the harness manufacturer for help." I do have a diode and holder that I could use. I had bought this on suggestion from American Autowire as my starter didn't have the extra lug for the cold weather bypass of the ballast. The unit is nice, except that you can't close the cover once the diode is installed. So I don't have cold weather down here so it just sits in the electric box. But I could use it if that is the problem. Where would I install it?
Coolerman
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The one wire to the alternator green plug is in the wrong place. It is in the L terminal. Move it down to the IG terminal. The alternator will not put out anything without that +12V to IG.
I also sell the correct connector for that alternator. Part # 2P7987. $13.95 plus shipping.
I also sell the correct connector for that alternator. Part # 2P7987. $13.95 plus shipping.
Thank you Coolerman. I know I had pulled the terminal out of the plug to inspect the connection of the wire to the spade and did not note which hole it was in. This morning when I took the picture and was re-inserting the plug it didn't feel like it was seating. So I worked it a little bit and it went in further. I wonder if it is a combination of the two "issues" that caused the engine to not stop when turning off the key. I will move that wire and see what happens. Thank you. Oh, you didn't finish the article on the starter rebuild
. I have picked up a new Bendix but haven't found a service manual instruction for how to replace it. And like many people, I count on you and your experience and knowledge. Lenny.
. I have picked up a new Bendix but haven't found a service manual instruction for how to replace it. And like many people, I count on you and your experience and knowledge. Lenny.
Coolerman
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I don't know what feeding +12V to the L terminal would do, but I bet when you move it to the correct place you might solve both issues!
Yes, there are several pages on the web page needing finishing! I actually am working on adding the mechanical stuff for the wipers right now to the Wiper Page...
Yes, there are several pages on the web page needing finishing! I actually am working on adding the mechanical stuff for the wipers right now to the Wiper Page...
If it wasn't for your wiper wiring "correction" I would still be trying to get those things working! While it did work on the bench and the first couple of times I used them, they no longer auto park. I just have to time turning them off to have them in the down position.
Coolerman
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It's your park switch contacts that need adjusting. Very common problem with these things.
The switching of the wire did the trick. Starts good, shuts down like it should. Thanks for looking at the picture and helping me out.
I guess I could actually remove the wiper motor out of the front side, seems like you have to pull it forward just to access the nut that connects to the linkage anyway. So one of these days when I get really bored, or it acts up, I will take a look at adjusting it. Did you see that you can no longer buy a new motor? And the places want $300-$400 for a used one!?!
I guess I could actually remove the wiper motor out of the front side, seems like you have to pull it forward just to access the nut that connects to the linkage anyway. So one of these days when I get really bored, or it acts up, I will take a look at adjusting it. Did you see that you can no longer buy a new motor? And the places want $300-$400 for a used one!?!
