Inside Rear View Mirror Night Light Operation - keywords dim head headlamp headlight ISRVM lamp

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

The map light is part of the inside rear view mirror. There is an ambient light sensor on the back of the mirror (the side facing the windshield) that is used to turn the headlights/DRL on and off. This light sensor is also used for the map light. When it is dark outside the map light will turn, but it will be dim. This feature is used to help light the interior of the truck when it is dark outside. The dim map light will turn off when it is light outside. When the map light switch is pressed the map light will turn on bright. When the map light switch is pressed again the light will turn off if it is light outside or stay on dim if it is dark outside.

To disable the dim light feature:

1. It must be dark outside or the light sensor on the mirror must be covered so the dim light feature is turned on.
2. When the dim light is on, press and hold the map light switch for about 3-5 seconds. The map light will turn on bright then turn off. This will now be the default setting for each ignition cycle.

To turn the dim light feature back on:

1. It must be dark outside or the light sensor on the mirror must be covered for the dim light feature to be turned on.
2. Press and hold the map light switch for about 3-5 seconds. The map light will turn on bright then go dim. This will now be the default setting for each ignition cycle. Now the map light will turn on to the dim setting when it is dark outside.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.