S30 Starter Wiring Modification
If you’ve had chronic starting issues with your Z—such as the solenoid clicking but the starter not turning—this simple modification may be the cure.
When the solenoid clicks, it confirms that your ignition switch is working. The starter itself is likely fine as well. However, testing the solenoid terminal on the starter with a voltmeter (key in START position) will often reveal a reading much lower than 12 volts—typically only 6–8 volts.
That’s enough to activate the solenoid, but not enough to keep it engaged. The click you hear is the solenoid disengaging. Over time, resistance from aging wiring and connectors in the circuit prevents full battery voltage from reaching the starter.
Solution: Install a starter relay to deliver full battery voltage directly to the solenoid. This also reduces the electrical load on the ignition switch, extending its life.
This minor project is inexpensive, quick to install, and can make a dramatic improvement in starting reliability.
*WARNING* - Do this diagnosis/mods at your own risk. We Are not responsable for any issues of your own doing.
Items Needed
- 12–14 gauge wire
- Relay intended for auxiliary driving lights
- Solder
The Modification
- Mount the relay on the inner fender panel as close to the starter as is convenient.
- Run a 12–14 gauge wire from the battery terminal (large ring wire end) on the starter to the #87 terminal on the relay.
- Run another 12–14 gauge wire from the #30/51 terminal on the relay to the solenoid terminal (push-on connector).
- The original wire from the ignition switch to the solenoid (yellow or yellow with black) may need to be extended to reach the #86 terminal on the relay.
- The #85 terminal needs a 14–18 gauge wire running to ground (frame or body).
Layout of Relay Pins
Sources Used
- Written by: John Walker