To begin

To begin the regulator tests, first, check to see that the regulator display is lit when the engine is running.

If the display is not illuminated, then follow these steps. Connect one of your test lamp wires to the ground terminal on the regulator.  Turn your ignition switch to the ON position (if the regulator’s brown (ignition) wire is connected to an oil pressure switch, connect a jumper wire across the oil pressure switch), then apply the test light’s other wire to the red (power) wire in regulator’s black 4-wire plug. Does the test light illuminate?

No – If the test light does not illuminate, follow the red (power) wire to its source and test for power there. If the red (power) wire has power at that location, replace the 10-amp fuse in the red (power) wire and re-check for power at the regulator wiring plug. If the wire still has no power at the regulator end, inspect for damage along the length of the wire and repair/replace as needed.

Yes – If the red (power) wire lights the test lamp, but the regulator display remains unlit, apply the positive probe of the tester to the brown (ignition) wire. If this illuminates the test lamp, then repair or replace any damaged wire or connectors until the test lamp indicates current at the regulator end of the brown (ignition) wire.

If the regulator is a Max Charge with an independent Positive Battery Sense wire, check that wire as well. Repair/replace any damaged wire, connectors or fuses if no voltage is recorded on that wire.

If the test lamp remains unlit, follow the brown (ignition) wire to its source and test the source with your test lamp.

If the regulator display is illuminated, yet charging is not occurring (be sure to wait beyond the 45-second delay before taking test readings), then apply the test lamp’s positive probe to the blue wire in the regulator’s black 4-wire plug and the negative probe to the regulator ground. If the test lamp does not illuminate, the regulator may be damaged. If the regulator is within the warranty period please call us.

If the test lamp does illuminate, the regulator is providing a field current and so the problem is likely to be elsewhere in the charging system.

Follow the field wire to its connection at the alternator. Disconnect from the alternator and apply the test lamp to the wire. Does the test light illuminate? If the lamp illuminates, the regulator and wiring harness are likely to be good.

It’s time to call a professional.