HELP!!!! '72 240Z Alternator Upgrade Gone Awry!!!!

[timhypo]

So, last week I finally got my '72 240Z running after a few years (previous owner says he parked it in 1989) and put a few hundred miles on it over the last week. It ran great with no issues, So, as I've been working on things, I've been collecting parts and the first mod was to be the ZX alternator. I pulled the old reg and alternator, installed the new one, and hooked it up. Except, I hooked it up wrong, undoubtedly partallt due to the previous owner's shenanigans with the cable colors. Anyway, I had the wire that's supposed to go to the BAT terminal on an E terlinal I believe this means Earth - a GROUND! To make things worse, I didn't notice before trying to fire it. WEll, there was a pop and then nothing worked, except the horn and brake lights.

So, any suggestions of how to further isolate this? It would appear that the PO removed the fusible link that's supposed to be between the starter and the rest of the mess of electronics, so I know that didn't pop. I thought the ammeter looked smokey, but it was dark. I've read that the ammeter is in the path of the positive of pretty much everything in the car's positive lead and that an ammeter that's out can cause this, how do I wire around it to check? Any other suggestions? I've spent the last two days picking through it with the volt-ohm meter and have learned little, I've poured through the results of tons of searches here, on zcar, and in Google, I'm at a dead-end, I fear. I need help!!!

[240260280z]

Dang, that needs your visual investigation to continue. My guess is that the problem is at the alternator or in the wiring between the alternator and the battery or fusebox. Does the alternator smell burned?

I did a quick check of the wiring diagram and there seems to be two fusible links on the 72. One at the starter and one at the alternator:

http://www.atlanticz.ca/zclub/techtips/wiringdiagrams/72_240z_wiring.pdf

[SteveJ]

The pop was most likely your ammeter. With the alternator shorted to ground, you had a large current flowing through the ammeter when you hit your starter, blowing it up. Your description was excellent in describing what still worked. From the battery, the cable goes to the starter. It would normally go from there to the fusible link, which you suspect is missing, and on to the fusebox. In the fusebox, it goes to the horn and brake lights. Another branch on the circuit goes through the ammeter to power the rest of the circuits. If you take out the ammeter, you kill the car.

[timhypo]

So, somehow I need to bypass the ammeter. I'm thinking from looking at this wiring diagram that Blue posted (link below my post) that I need to connect the white wire going into the ammeter to the Yellow/Red wire coming from the ammeter. This assumes that there is voltage on the white wire when I check it - it's the line from the starter, so it should be hot. The yellow-red appears to eventually supply voltage to the ignition switch.

http://www.atlanticz.ca/zclub/techti...40z_wiring.pdf

[SteveJ]

Not quite right. The positive and negative leads on the ammeter need to be jumpered out. Replacing/repairing the ammeter is an even better solution. The positive is a white wire, and the negative is a white/red wire. Use a 10 AWG wire since the wire would be carrying a significant amount of current. By the way, I don't recommend this action unless you are fairly compentent with wiring. If the wiring comes loose and touches ground, you could have an electrical fire, especially since you don't think you have fusible links in place.

Another user on here has used Bob's Speedometer to repair his tachometer. They do other gauges as well. You could also try Zbarn for a replacement ammeter.

[timhypo]

So, prior to reading the latest post, I did my experiment connecting the white wire to the yellow/red wire using a piece of 22g and a pair of alligator clips and the car fired right up. It's not charging the battery, but I can look at that next...

[SteveJ]

Well, you've proven that the pop was from the ammeter and that you're probably at least a little dangerous when it comes to electricity.

At least the 22 AWG wire would probably have functioned similar to a fusible link.

Please do not drive your car around until you fix your electrical issues, or at least carry about a fire extinguisher or two that is rated for electrical & gasoline fires. It could save you from losing your car.

[timhypo]

I'm not going to drive it until it's, at least, charging the battery. As has been noted in the past, the existing ammeter isn't compatible with the ZX alternator, so a new gauge is in the future plans, when I replace the rest of the gauges. For now, I'll bypass is and drive the car...

[SteveJ]

Um, I put in a ZX alternator in my 73 in 2001. The ammeter works just the way it's supposed to. Check the more recent posts on this subject. I don't know where the idea that the gauge doesn't work came from, but it isn't correct.

[beermanpete]

Take the ammeter out of the car and test it separately. Open it if needed. It comes appart easily.

The ammeter connects to the wires with 2 threaded studs and ring terminals. You could easily bypass the ammeter by shorting these together with a bolt and nut.

As for the ZX alt. upgrade, the alt. has nothing to do with the meter. There may some wiring mods requried to make the 2 work together but they are not mutually exclussive.

[timhypo]

Ok, it's been a long, cold, lonely winter and I've had the car parked while I work on other projects, automotive and otherwise. Well, yesterday, I decided it was time to start working on this car again. I charged the battery up and got it to fire pretty easily, given it had been parked for almost 6 months. It's still, however, not charging the battery. I went through and double-checked that the wiring matches what's depicted on http://datsunzgarage.com/engine/index.htm under the 'alternator upgrade' section. All appears well there. Beyond that, what testing can I do? I know I can take the alternator to an auto parts store and put it on their testing machine, but I'm wondering what testing I can do at home before going through the trouble of pulling it and driving across town. I have a multimeter and know how to use it. I was thinking that I could jumper between the 'BAT' terminal and the battery's positive terminal, then check to see if it's charging. Should the alternator 'BAT' terminal have a specific voltage on it? One other clue that may prove useful is that the car won't shutoff on its own when I pull the key despite the fact that I have the diode mentioned on the link above installed per their directions. As their directions aren't terribly clear, I tried reversing the diode but the car still has the same behavior. Any ideas? This is maddening, the car is running great and I'd love to start driving it as my daily, but without charging the batter, that's a no-go.

[timhypo]

Ok, it's been a long, cold, lonely winter and I've had the car parked while I work on other projects, automotive and otherwise. Well, yesterday, I decided it was time to start working on this car again. I charged the battery up and got it to fire pretty easily, given it had been parked for almost 6 months. It's still, however, not charging the battery. I went through and double-checked that the wiring matches what's depicted on http://datsunzgarage.com/engine/index.htm under the 'alternator upgrade' section. All appears well there. Beyond that, what testing can I do? I know I can take the alternator to an auto parts store and put it on their testing machine, but I'm wondering what testing I can do at home before going through the trouble of pulling it and driving across town. I have a multimeter and know how to use it. I was thinking that I could jumper between the 'BAT' terminal and the battery's positive terminal, then check to see if it's charging. Should the alternator 'BAT' terminal have a specific voltage on it? One other clue that may prove useful is that the car won't shutoff on its own when I pull the key despite the fact that I have the diode mentioned on the link above installed per their directions. As their directions aren't terribly clear, I tried reversing the diode but the car still has the same behavior. Any ideas? This is maddening, the car is running great and I'd love to start driving it as my daily, but without charging the batter, that's a no-go.

Ok, disregard this, I figured it out. The not charging issue was because of a broken wire INSIDE of the plastic shielding. Wouldn't have found that without the alternator. The not turning off issue was actually the fault of my ignition switch. Some of the local gangsters tried to go joyriding in it last year and screwed up the switch with a screwdriver, making 'OFF' real hard to find and, when I thought it was in the 'off' position, it was actually in the 'ACC' position. Awesome. Now to drive it until I get up the courage to try the distributor upgrade...