Pinpoint Test Aa - Display Not Lit, Too Dim, Or Totally Blank

Turn ignition off. Turn parking lights on. Observe instrument cluster displays while operating illumination dimmer control. If other displays do not dim properly, go to next step. If other displays dim properly, go to step 3).
Turn parking lights off. Disconnect EIC. Turn parking lights on. Measure voltage at pin No. 3 (Light Blue/Red wire) on message center harness connector while operating illumination dimmer control. If voltage varies between about zero to battery voltage, replace EIC. If voltage is not as specified, repair Light Blue/Red wire.
Check for defective fuses No. 9 and 11. Fuse block is below instrument panel, to left of steering column. Measure voltage at fuse No. 11 while operating illumination dimmer control. If voltage is not as specified, go to next step. If voltage varies between about zero to battery voltage, repair Light Blue/Red wire.
Using a test light, backprobe terminal "I" of headlight switch while operating illumination dimmer control. If test light does not change in intensity, go to next step. If test light dims completely and brightens to full intensity, repair Light Blue wire between headlight switch and EIC.
Unplug connector from headlight switch. Check for battery voltage at Tan/White wire at harness connector. If battery voltage exists, replace headlight switch. If battery voltage does not exist, inspect fuse No. 9. If fuse is okay, repair Tan/White wire from fuse block to headlight switch.