D150 1/2 Ton Pickup 2WD V6-239 3.9L VIN X FI (1988)
Volt Meter Gauge: Testing and Inspection
1. Remove voltmeter from cluster.
2. With ignition switch in On position, check for battery voltage across B+ pin and Ground pin.
3. Voltmeter indicates regulated alternator output or battery voltage, whichever is greater.