Alternator and Regulator Circuit Troubleshooting

Make sure the battery is sufficiently charged (see BATTERY TEST ).
Raise the hoist to full height.
Hook up the ammeter, 0-400 A, to the starter subharness.

Fig 1: Hooking Up Ammeter To Starter Subharness
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Lower the hoist.
Hook up the voltmeter, 0-20 V (accurate within 0.1 V) to T101.

Fig 2: Hooking Up Voltmeter To T101
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Start the engine. Hold the engine speed at 3,000 RPM without load (in Park or Neutral) until the radiator fan comes on, then let it idle.
Raise the engine speed to 2,000 RPM, and hold it there.
Turn on the headlights to high beam, and measure voltage at the underhood fuse/relay box terminal.
Is the voltage between 13.9 and 15.1 V?
1. YES - Go to step 9.
2. NO - Repair the alternator components:
  - K20A3 engine (see ALTERNATOR OVERHAUL ).
  - K20A2, K20Z1 engines (see EXPLODED VIEW - K20A2, K20Z1 ENGINES ).
Read the amperage at 13.5 V.
NOTE: Adjust the voltage by turning on the blower motor, rear window defogger, brake lights, etc.

Is the amperage 60 A or more?
1. YES - Alternator/regulator operation is OK. Go to Alternator Control Circuit Troubleshooting (see ALTERNATOR CONTROL CIRCUIT TROUBLESHOOTING ).
2. NO - Repair the alternator components:
  - K20A3 engine (see ALTERNATOR OVERHAUL ).
  - K20A2, K20Z1 engines (see EXPLODED VIEW - K20A2, K20Z1 ENGINES ).