Ignition Voltage loss at startup-70 510 automatic

[jefe de jefes]

Any idea what would cause a drop from 12v to less than 1v while cranking the vehicle. I'm measuring the voltage from the black with white stripe wire that goes to the positive side of coil. the only way I have been able to start the vehicle is to run 12v direct to the coil. I checked my 521 and I get a drop of 1-2v while cranking so something is def wrong with the 510. Any ideas?

[datzenmike]

Try unplugging the ignition switch a few times to clean the contacts.

 

Power to the ignition switch comes from the positive cable on the starter through a small fusible link. All I have is a diagram so I don't know exactly how it looks. Check for any poor or corroded/loose connections on or near the starter.

[moparvwfreak]

bad ignition switch?? never can tell. i had a rabbit do that to me once.

[datzenmike]

Yeah that's a better one. If it was the source voltage that was dropping then the starter solenoid would also drop and the solenoid would just chatter.

 

Make that bad connection at ignition switch or bad ignition switch.

[jefe de jefes]

Ill try another ignition switch. I have a few laying around. Now would be a good time to install a kill switch.

[Wharf Rat]

While cranking the ballist resister is jumped it has to be that circut. Bad wire end, switch maybe. But I think it's under the hood because it cranks fine. You can run one from your soleniod. Good luck.

[Wharf Rat]

I forgot to say that the res. is jumped while cranking for a nice hot spark. the starter lowers voltage some as you saw while testing.

[ggzilla]

Bad wiring connection. Could be in the switch, but more likely is at the resistor or coil. Those old Datsun spade connectors get corroded.

[jefe de jefes]

Looks like it's the switch. I was using a 521 one, and when I went back to the original switch it started. After messing with it a bit though. Guess the 521 and 510 switches aren't compatible. Gives me a reason to go to the junk yard. I think the z cars have the same type.