Instrument Cluster Display Does Not Dim Or Goes Blank With Head/Park Light Switch In Head Or Park Position

Turn ignition off. Disconnect instrument cluster connector C1. Put head/park light switch in PARK or HEAD position. Put dimmer control on LO. Measure voltage between instrument cluster connector C1 (Yellow wire), terminal F5 to ground. See Figure. If battery voltage is not present, check Yellow wire for an open or short circuit to ground. If battery voltage is present, go to next step.
Measure voltage between instrument cluster connector C1, terminal F4 (Gray wire) and ground while adjusting dimmer control. If voltage varies with dimmer control, go to next step. If voltage does not vary with dimmer control, go to step 4).
Check instrument cluster connector C1, terminals F4 and F5 for good terminal contact. If terminal contact is okay, replace instrument cluster. See INSTRUMENT CLUSTER under REMOVAL & INSTALLATION.
Leave dimmer module connector connected. Backprobe dimmer module connector and measure voltage between terminal "C" and ground while adjusting dimmer control. If voltage varies with dimmer control, check Brown wire for an open or short circuit to ground. If voltage does not vary with dimmer control, check Dark Green and Yellow wires for an open circuit or short to ground. Also check headlight switch, in-line connectors, and dimmer module connectors. If all circuits are okay, replace dimmer module.