got this from yotatech:
http://yotatech.com/showthread.php?t=40435
Auto CLimate Control light bulb location/replacement
The auto climate control in the 99-01 Toyota 4Runner Limited has (4) replacable bulbs. (2) light up the LCD display and the other (2) light up the following buttons: Auto, Out/T, Mode, *Off, A/C & the outer rotorary controls.
81850-35020 LCD Display Bulb
81850-35030 Background bulb for the rotary/function buttons
In addition to the above (4) bulbs there are (5) LEDs (not user serviceble) that light up each button when they are activated. The LEDs that are directly soldered to the PCB assembly and not meant to be replaced by end user.
To replace any of the bulbs listed above, you will need to remove the entire climate control out of the dash and dissamble it in order to replace the bulbs. (Dont panic, its not that bad as it sounds!!).
Accessing the dash
In order to access the dash you will need to remove the cup holder plastic assembly piece, the gear trim panel and the dash trim.
1. Start by opening the center console door. The cup holder is then removed by gently pulling it up.
2. Next the gear trim panel is removed in the same fashion. If your model is a 4WD model then pay attention the plastic around the 4WD lever. This snaps out from trim by lightly tugging on it.
3. Finally, the dash piece is removed by gently pulling on it. There a (5) clips that hold the trim to the dash. I found that starting from the bottom and working your way up does the trick.
4. Once the dash piece is out, you will need to disconnect all of the connectors. All of these are quick disconnect, so just press on a tab and they are released. Remember to double check that they are all back in when the dash piece before placing it back.
Removing the Climate Control
1. Prior to removing it determine which bulb is bad by turning the ignition on and noticing which area is dim.
2. There are (3) screws that secure the climate control to the dash. (2) on the passenger side and (1) the drivers side. Remove all (3) with a phillips screwdriver.
3. The climate control should just come out at this point. Next disconnect the (2) electrical connectors (quick disconnect) behind the climate control.
4. Remove the (2) phillip screws (located behind the black control/trim) that secure the entire LCD/Black trim to the actual control box.
5. This should give you access the front of the PCB (Printed Circuit Board).
6. The replaceable bulbs are identified as PL1, PL2, PL3 and PL4. PL1 and PL2 are the larger ones (display bulbs). PL2 and PL3 smaller bulbs (light up the remaining of the buttons).
7. The bulbs are removed by turning them clockwise with your hand or a small flatblade screwdriver.
8. Insert the new bulb, re-connenct the (2) quick disconnects from step 3 and turn the ignition ON to test.
9. Put everything back together by Reversing the process and you're done!!
(writeup is by YT member: Ctapia)
