LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Ford >> 1989 >> Probe GL, Standard >> Repair and Diagnosis >> Electrical >> Charging Systems >> Alternator - 2.2L Models >> On-Vehicle Tests >> Regulator Power Source Test
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Regulator Power Source Test

NOTE: Alternator wiring plug must be disconnected for the following test.
  1. Disconnect alternator wiring plug. Turn ignition switch to "ON" position (engine not running). Connect voltmeter positive lead to alternator wiring plug terminal "S". See Fig 1. Connect negative voltmeter lead to alternator rear housing.
  2. If reading is same as battery voltage, proceed to ROTOR FIELD COIL TEST . If reading is less than battery voltage, problem is indicated between terminal "S" wire and battery.
Fig 1: Alternator Terminal Locations
G106359Courtesy of FORD MOTOR CO.


  1. Disconnect alternator wiring plug. Turn ignition switch to "ON" position (engine not running). Connect positive voltmeter lead to terminal "S" of alternator wiring plug. See Figure. Connect voltmeter negative lead to alternator rear housing. Record voltage reading.
  2. If voltage at terminal "S" is same as battery voltage, proceed to ROTOR FIELD COIL TEST . If voltage at terminal "S" is less than battery voltage, problem is indicated in wiring between ignition switch and terminal "S". Reconnect alternator wiring plug.
scientia non olet · About LEMON Manuals