[hot wheels1]

I have a 1977 Datsun 280Z. Currently I have replaced 2 Alternators, 1 voltage regulator and several batteries because something is draining my electrical system. The latest advice I was given was that it is my voltage regulator. It is a new one I did not think it needed to be adjusted. I get 12.5 volts at the battery when car is off and 13.7 with the car running. I did several test and when I turn my side marker lights are headlights on the volts start dropping really fast. I have been stranded a few times in the last couple of months and it is always at night or when I drive during the day with headlights on. Now I only drive it during the day and keep a fully charged battery with me. I have removed all of the fuse and the headlight switch fusible link and the volts still drop (-.1) every second. I removed the power wire from the steering column stalk red/*********** wire and still the volts are dropping. The only plug that did not drain the volts was when I disconnected the 9 pin connector from the combination switch. I will adjust the voltage regulator tomorrow but I am reading that the best thing to do would be to upgrade to a 280zx alternator. Concerned about the headlights draining the battery. Any suggestions?

 

[bonfire79]

Get the FSM for the 77 model Z and go through troubleshooting the electrical system. best place to start.
its free at www.xenonzcar.com

cheers,

Bon

 

[Dave Datsun Tech.]

When I got my 240Z, the new looking alternator had burnt diodes and wasn’t charging. I replaced the alternator and it was charging 60 amps! I replaced the regulator and it was still charging 60 amps!
On a ‘71 240Z, the voltage regulator has a white battery sense wire that is spliced into the main power wire from the starter. If this wire gets disconnected, the regulator won’t know that the alternator is putting out and will go full field, max output until it burns out the diodes in your alternator or boils your battery.
That white battery sense wire is spliced to the heavy power wire in the harness by that body ground connection near the starter. The splice is under some green tape in the harness.
Mine became disconnected and I don’t see how it was attached in the first place. There was no crimp connector. If the 18 gauge wire was soldered to the 10 gauge wire, the solder had disintegrated.
Being directly below the battery, acid may have gotten into the harness and dissolved the connection. The wire had light green powder on it but didn’t look that bad. Even after 50 years, you wouldn’t think a crimp connector would completely dissolve.
Even with internally regulated alternator, That sense wire may matter.

 

[gaat1954]

When I got my 240Z, the new looking alternator had burnt diodes and wasn’t charging. I replaced the alternator and it was charging 60 amps! I replaced the regulator and it was still charging 60 amps!
On a ‘71 240Z, the voltage regulator has a white battery sense wire that is spliced into the main power wire from the starter. If this wire gets disconnected, the regulator won’t know that the alternator is putting out and will go full field, max output until it burns out the diodes in your alternator or boils your battery.
That white battery sense wire is spliced to the heavy power wire in the harness by that body ground connection near the starter. The splice is under some green tape in the harness.
Mine became disconnected and I don’t see how it was attached in the first place. There was no crimp connector. If the 18 gauge wire was soldered to the 10 gauge wire, the solder had disintegrated.
Being directly below the battery, acid may have gotten into the harness and dissolved the connection. The wire had light green powder on it but didn’t look that bad. Even after 50 years, you wouldn’t think a crimp connector would completely dissolve.
Even with internally regulated alternator, That sense wire may matter.
View attachment 112867

I had the Same Problem your describing, when I had my 1972 240z, way back in 1980.. .. . My Regulator was mounted on the Right hand side of the Engine compartment, , the Connector of the White Wire,, was all corroded,green etc , causing the diodes to Burn Out .. THE Parts places were getting sick of me, buying diodes rectifers all the time .. then I traced every wire,, and found it ( The Big White Wire) by the connector going to the Regulator ..

 

[gaat1954]

I have a 1977 Datsun 280Z. Currently I have replaced 2 Alternators, 1 voltage regulator and several batteries because something is draining my electrical system. The latest advice I was given was that it is my voltage regulator. It is a new one I did not think it needed to be adjusted. I get 12.5 volts at the battery when car is off and 13.7 with the car running. I did several test and when I turn my side marker lights are headlights on the volts start dropping really fast. I have been stranded a few times in the last couple of months and it is always at night or when I drive during the day with headlights on. Now I only drive it during the day and keep a fully charged battery with me. I have removed all of the fuse and the headlight switch fusible link and the volts still drop (-.1) every second. I removed the power wire from the steering column stalk red/*** wire and still the volts are dropping. The only plug that did not drain the volts was when I disconnected the 9 pin connector from the combination switch. I will adjust the voltage regulator tomorrow but I am reading that the best thing to do would be to upgrade to a 280zx alternator. Concerned about the headlights draining the battery. Any suggestions?

Check all your Wire connectors at each and every Light... Headlights,, Front Side Markers ,, Rear Tail Light , Rear Red SideMarkers... run continutity tests ... if you see corrosion clean and apply a Little Lithium greese.. ... clean clean clean ,