4.6StangRage Posted February 21, 2012 Share Posted February 21, 2012 first of all, I did an alternator test and found that my alternator works within Specifications even when loaded with a carbon pile from a VAT-40. The molded side of my voltage regulator was cracked so I replaced it with a used but working voltage regulator. I have everything plugged in properly and notice now I do not have the charge light on any more. Even though I dont have the light on anymore it still does not charge. I looked in my service manual and it states that the voltage regulator is interconnected to the Starter Interlock Unit, but I cant seem to find this unit in my Z. I have a 1976 280Z 4speed 2+2 can anyone show me a pic of where this device is located and what it looks like because the illustration in the manual looks nothing like what i have under my dash. Btw the Z starts and runs great, it is just not charging. if anyone has any ideas on what i can do or has any information on this interlock unitI would certainly appreciate it! Thanks, Randy Quote Link to comment Share on other sites More sharing options...
nash542001 Posted February 21, 2012 Share Posted February 21, 2012 Is it a california model? I had some kind seat interlock thing underneath the passenger seat of my 76 280Z 2+2. Quote Link to comment Share on other sites More sharing options...
ttodhunter Posted February 21, 2012 Share Posted February 21, 2012 What exactly do you mean by "not charging"? Does the battery drain when the engine is running? What is showing on the volt meter on the dash? What is the voltage reading across the battery when the engine is running? If the charge light is off when the engine is running, it thinks it's getting voltage... I have a '76 4 speed coupe, I don't have any interlock that I know of... Quote Link to comment Share on other sites More sharing options...
4.6StangRage Posted February 21, 2012 Author Share Posted February 21, 2012 I'll look because it is a California model. I can remember some electronics under the passenger seat. Now that I am thinking about it, the connectors seem familiar. Quote Link to comment Share on other sites More sharing options...
NewZed Posted February 21, 2012 Share Posted February 21, 2012 I looked in my service manual and it states that the voltage regulator is interconnected to the Starter Interlock Unit, Which service manual are you looking at? The 1976 Nissan FSM doesn't show any "interlock unit" in the alternator or regulator circuits that I can see. My 76 coupe doesn't have one. The relay under the passenger seat is probably the brake warning lamp check relay. Quote Link to comment Share on other sites More sharing options...
4.6StangRage Posted February 22, 2012 Author Share Posted February 22, 2012 What exactly do you mean by "not charging"? Does the battery drain when the engine is running? What is showing on the volt meter on the dash? What is the voltage reading across the battery when the engine is running? If the charge light is off when the engine is running, it thinks it's getting voltage... I have a '76 4 speed coupe, I don't have any interlock that I know of... The battery drains slowly as the engine is running. The voltage reads as 12.4 when the engine is running and declines depending if i use my headlights or not. I do not get field signal to the alternator and i am not exactly sure why. maybe I have the wires coded wrong. My manual says 1975 and my Z was built 10/1975. I know it is a 1976 year model but my mentor (old friend) about 8 years ago said that I should get the 1975 manual. I have 6 pins going to the volt regulator but the regulator, which I pulled off of a 1977 has only 5 pins. Quote Link to comment Share on other sites More sharing options...
4.6StangRage Posted February 22, 2012 Author Share Posted February 22, 2012 Another piece of information, My wiring has been modified and I discovered that it was wired incorrectly. I found a charging system diagram from a FSM online and re wired it. Now I have a signal at the field wire going to the alternator but I have no output coming from the alternator. In fact All I am reading from the system is battery voltage. At all points on the charging system, I confirmed continuity through all circuits. I am going to do a voltage drop on the field circuit because all i read was 2-3 volts on the field circuit. I think the reason why my charge light isnt on is because it is producing a minimal amount of voltage due to the lack of field excitation. I am thinking there should be battery voltage at the field terminal. I should read up on this because I think i am missing a crucial element, what do you guys think? Quote Link to comment Share on other sites More sharing options...
morbias Posted February 22, 2012 Share Posted February 22, 2012 If the regulator only has five pins then I would start looking at what connection is missing there. Quote Link to comment Share on other sites More sharing options...
NewZed Posted February 22, 2012 Share Posted February 22, 2012 Are you measuring output at the alternator, at the battery or at the regulator? Should give you a clue as to if the alternator is producing but the current is not making it to where it's supposed to go, or if the alternator is just not producing. Quote Link to comment Share on other sites More sharing options...
beermanpete Posted February 22, 2012 Share Posted February 22, 2012 Another piece of information, My wiring has been modified and I discovered that it was wired incorrectly. I found a charging system diagram from a FSM online and re wired it. Now I have a signal at the field wire going to the alternator but I have no output coming from the alternator. In fact All I am reading from the system is battery voltage. At all points on the charging system, I confirmed continuity through all circuits. I am going to do a voltage drop on the field circuit because all i read was 2-3 volts on the field circuit. I think the reason why my charge light isnt on is because it is producing a minimal amount of voltage due to the lack of field excitation. I am thinking there should be battery voltage at the field terminal. I should read up on this because I think i am missing a crucial element, what do you guys think? The charge light is not connected to the field circuit. It is connected across the "Ig" and "L" terminals on the regulator. The "Ig" terminal is at battery voltage (+12) when the car is on. The "L" terminal is grounded through the regulator when there is no alternator output. As soon as the alternator output is above a set threshold a relay in the regulator opens and breaks the ground path and the light will go out. You need to test the alternator separately from the regulator by "full-fielding" it. This is simply disconnecting the regulator and connecting the "F" terminal directly to the battery. If the alternator is working correctly the output current should be very close to the rating in the manual (60 amps at 5000 RPM). The battery voltage will rise quickly to well above 15 volts so be careful and do not run the engine long while performing this test. If the output current and voltage do not rise as expected the alternator is bad. Make sure the main output wire and ground are properly connected and is good condition and make sure the V-belt is in good condition, adjusted correctly, and not soaked in oil. I learned the hard way once that an oil leak can cause the belt to slip and prevent proper charging. The VAT-40 you mentioned in your first post can do the full-field test. Having access to the VAT-40 is a luxury. Use it to your best advantage. Quote Link to comment Share on other sites More sharing options...
4.6StangRage Posted February 22, 2012 Author Share Posted February 22, 2012 I did about 75 percent of what you just said. The charge light does go through the white/red wire on the regulator. For some reason there is only 5 pins on the '77 I pulled the pigtail and portion of harness from. The signal coming out of the field section of my regulator to the alternator has a dim light when a test light applied. I know there is fielding going on but I am not sure if there is enough. Quote Link to comment Share on other sites More sharing options...
beermanpete Posted February 22, 2012 Share Posted February 22, 2012 I did about 75 percent of what you just said. The charge light does go through the white/red wire on the regulator. For some reason there is only 5 pins on the '77 I pulled the pigtail and portion of harness from. The signal coming out of the field section of my regulator to the alternator has a dim light when a test light applied. I know there is fielding going on but I am not sure if there is enough. The brightness of the test light will indicate (to some extent) the voltage present at the field winding. If the battery voltage is only 12 volts as you said the field current should be maximum which means the voltage on the field should be essentially the same as the battery voltage an the test lamp will be bright. Since the test lamp is dim it suggests the regulator is not supplying enough current to the field winding. Which wire is missing from the connector? Quote Link to comment Share on other sites More sharing options...
4.6StangRage Posted February 23, 2012 Author Share Posted February 23, 2012 yeah I should use a meter to determine field current. Exactly, that is what i am thinking, because there should be more fielding to the alternator. The pin that was missing on the 77 was the L terminal. In other words, the White/ red wire on the regulator. I think it is blue on the engine compartment harness side. I need to determine why the field strength is not where it should be. Quote Link to comment Share on other sites More sharing options...
4.6StangRage Posted February 23, 2012 Author Share Posted February 23, 2012 I think my voltage regulator is shot. I get a considerable amount of resistance and from reading my FSM it looks like the P1 terminal is open therefore only giving the current the path to flow through the resistor. Quote Link to comment Share on other sites More sharing options...
beermanpete Posted February 23, 2012 Share Posted February 23, 2012 The missing "L" connection won't keep the charging system from working but it does explain why the charge light is not lit. All year models show this wire in the service manual but the 74 and 75 don't have the light so maybe the regulator is from a 74 or 75? In your first post you said the replacement regulator is used but working. How do you know it is working? You never clearly stated that you full-fielded the alternator. Did you actually do this? If so, what was the result? Quote Link to comment Share on other sites More sharing options...
4.6StangRage Posted February 23, 2012 Author Share Posted February 23, 2012 I jumped the A post to the field post to test the alternator. I even loaded it with the VAT 40 and it worked within specs. To be honest, I was not 100% sure that the regulator worked. It was an educated assumption by inspection of the car. I determined that my regulator is faulty because of the massive voltage drop like it has an open on one part if the internal circuitry with only one path to go and that is through the 'R1' resistor. Quote Link to comment Share on other sites More sharing options...
beermanpete Posted February 23, 2012 Share Posted February 23, 2012 I agree, your regulator is bad. You might be able to fix it. The cover comes off the regulator. If the relay contacts are not badly worn you could clean and adjust the contacts to see if it will work again. Otherwise just buy a new regulator and be done with it. Quote Link to comment Share on other sites More sharing options...
4.6StangRage Posted February 23, 2012 Author Share Posted February 23, 2012 I wish I could fix it but it is molded therefore it wont come apart. Quote Link to comment Share on other sites More sharing options...
NewZed Posted February 24, 2012 Share Posted February 24, 2012 You must have one of the aftermarket solid-state replacements for the mechanical regulators. I've read that they aren't very durable. You can get a replacement or do the change to an internally regulated alternator. Both systems put out 60 amps max though, so the benefit to swapping to internal regulation is small. Quote Link to comment Share on other sites More sharing options...
4.6StangRage Posted February 24, 2012 Author Share Posted February 24, 2012 You must have one of the aftermarket solid-state replacements for the mechanical regulators. I've read that they aren't very durable. You can get a replacement or do the change to an internally regulated alternator. Both systems put out 60 amps max though, so the benefit to swapping to internal regulation is small. I am going to look into the delco remy alternator swap. I am going to get a bracket from a junkyard Z and modify it instead of possibly ruining my current one. 94 amps would be nice but i am not exactly sure of why i would need so many amps especially since i dont plan on installing any amplified stereos or anything like that. Quote Link to comment Share on other sites More sharing options...
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