S30 Starter Wiring Modification

If you have had chronic starting problems with your Z (solenoid click but starter doesn't turn) this might be the cure you need. If the solenoid clicks, you know your ignition switch is OK. Probably nothing wrong with the starter either. Putting a voltmeter on the solenoid terminal on the starter with the key on the "START" position will probably show a reading of much less than 12 volts, likely 6-8 volts. That's enough to actuate the solenoid but not enough to keep it engaged. The click you hear is the solenoid returning to rest. There is just too much resistance (from age) in the circuits involved to deliver 12 volts. This minor project will deliver full batter voltage to the solenoid and take the load off of the ignition switch.

Items Needed

  • 12-14 gauge wire
  • Relay intended for auxiliary driving lights
  • Solder

The Modification

  1. Mount the relay on the inner fender panel as close to the starter as is convenient.
  2. Run a 12-14 gauge wire from the battery terminal (large ring wire end) on the starter to the #87 terminal on the relay
  3. Run another 12-14 gauge wire from the #30/51 terminal on the relay to the solenoid terminal (push on connector)
  4. The original wire from the ignition switch to the solenoid (yellow or yellow with black) may have to be extended to reach the # 86 terminal on the relay.
  5. The #85 terminal needs a wire (14-18 gauge) running to ground, frame or body."

Layout of Relay Pins