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Discussion Starter #1
Wondering if anyone has any idea why lights are all gone out in heater controls and clock. Its the limited edition with push button type controls. Everything works fine but when I turn on the park or headlights, no lights come in the heater controls or display. Dimmer control works fine for dash, radio and gear selector, but it has no affect on the heating controls or clock display as they are not on. Clock display lights up fine when headlights or park lights are not in use but as soon as you turn on headlights or park lights the clock goes out. Anyone have any idea whats going on. Thinking i may end up having to change entire ac/heating control assembly as no bulbs to be changed as its led.
 

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Have you tried the full range of the dimmer?
 

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Thinking i may end up having to change entire ac/heating control assembly as no bulbs to be changed as its led.
The HVAC lights are not LED and you can change them which are normal bulbs. To change them you need to remove the radio and the HVAC cover and the bulbs are behind the control. This thread has some info.
 

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Discussion Starter #5
The limited does not have knob control...its push button...and there are no light blubs in there...they are led only. Dimmer switch works fine for everything else just not heater/clock
 

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Discussion Starter #6 (Edited)
Went to wrecker today and tried another ac/heater assembly....same thing..no lights when headlights/park lights are on. Wondering if there is some type of relay/fuse in the wiring harness before it reaches the plug on back of the ac/heater assembly. Upon further investigation, might have been a faulty unit from wreckers (my luck). All the dimmer controlled wires going to hazzard, 4x4, map light (light above heated seats, wiper warmer) all have dark green and light green wires that control there brightness. I put volt meter across each circuit and found volts would go from 0 to 3.5 depending on position of dimmer switch (btw all them circuits work perfect). I then found these two wires in the harness going to the ac/heater assembly, doing the same test and it showed same results, 0 to 3.5 depending on position of dimmer switch. This result is leading me to believe that its the ac/heater assembly itself. Going to have to go to another wreckers and get another ac/heater assembly and try it again. New one at Toyota is $2100.00 CRAZY!
 

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Make sure the assembly has a good GROUND.
 

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Wondering if anyone has any idea why lights are all gone out in heater controls and clock. I....... Dimmer control works fine for dash, radio and gear selector, but it has no affect on the heating controls or clock display as they are not on.
What about the background illumination of the following switches. Note that I am asking about the dim background lighting and NOT about the orange indicator lights. This background lighting is usually so dim that it can only be seen in total darkness. If these are off as well, then I suggest checking and replacing the 7.5 A "panel fuse". This will be a brown fuse located in the interior fuse panel.


  • The Auto LSD Switch
  • The light in the front console
  • The 4WD Button
  • The DAC Switch
  • The hazard warning switch
  • The seat heater buttons
 

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Just checked our '06 Limited tonight.

With the key on or engine running and the park/headlights off:
The dimmer rheostat only changes the instrument cluster brightness.
The radio and heater/AC knob and button lights are off. Clock is on a constant brightness.

Then with the park or headlights on:
All lights are on and their brightness is controlled by the dimmer with the clock lighting tracking the odometer brightness.

Obviously that's not what yours is doing, and since the yard unit is doing the same thing I'd suspect something in the dimmer circuit or wiring. If it isn't a bad ground or fuse it'll be time to look at the schematics.
 

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Discussion Starter #10 (Edited)
Ground is good. All other lights working as they should as asked above. Everything works as normal except when putting on park or headlights, then clock goes dark (no lighting in: clock or three round heater/ac push button controls) but everything still functions, even clock, just no illumination. Going to wreckers today to try another assembly. Basically seems that the dimmer control lights went out on the clock ac/heater control assembly. There is only one white wire harness plug that connects to this with about 10 wires into it, so just gotta figure out what wire does what and see why dimmer wires not working. Hopefully they are all ok and it is the assembly because I can get whole replacement for $75 at wreckers. Will save a lot of time rather then having to trace all wires in harness.
 

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Will do. Going to wreckers tomorrow to try another assembly.
My guess is you'll get the same result because the problem isn't in the assembly. Maybe try another dimmer control.
 

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Discussion Starter #12
Yes, was thinking same thing, going to see if the wreckers got another dimmer control, and try it. Just hoping I can find simple solution to this, rather then tracing wires...errr. Does anyone know what the wiring code is for the plug that goes into the back of the ac/heater assembly because tracing them wires is probably the next step, mainly the wires that control the dimmer function of the unit. I think they are dark green and light green but I got three dark green and one light green coming from that harness.
P.S. really appreciate all the responses and ideas, keep them coming..lol.
 

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Dimmer control works fine for dash, radio and gear selector,

I originally missed the part about the light on the gear selector. The gear selector light gets power from the same fuse as all the other switches I mentioned in my earlier post. So most likely that fuse is good, but I still recommend checking the other lights to verify this.

The dimmer rheostat must be working if some lights do change when it is turned.

The difference between the "gear selector" light, and all the switches that I listed, is that current flows to ground through two different connections on the combination meter. So if you can verify that those other switches do not light up, then we can narrow down the source of the problem.

Try turning the dimmer rheostat to the indent position, as this bypasses the variable resistor, and sends a signal to the combination meter on a different pin. This should trigger a different response from the combination meter.
 

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Discussion Starter #14
Just tried another heater/ac assembly and a different dimmer control switch, made no difference. Still no illumination for clock or heater controls when headlights or park lights are on. Every other dash light: the instrument panel cluster, gear selector, hazard, 4x4, down hill assist, heated seats..etc works as it should. Wonder if there is a fuseable link? Before all this issue started I was plugging phone charger into charging socket on dash when notice small spark (faulty phone charger) maybe this may of had an effect on it but ruled it out cause charging port working perfect and am guessing this is a different circuit.
 

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JEvery other dash light: the instrument panel cluster, gear selector, hazard, 4x4, down hill assist, heated seats..etc works as it should.
Now your making this complicated!

The clock lighting is in parallel with all the switches that I listed. If these switches work, then so should the clock unless a wire is broken/disconnected. Since the clock works with the headlights OFF, then the wiring should be good.

It appears that the AC panel is in parallel with the same circuit as the shifter light , which is also working OK.

Have you tested the lights with the dimmer control in the detent position?
 

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Discussion Starter #16
Yes Rickl all the lights you mentioned are working with the dimmer controller EXCEPT the clock light and heater/ac control backlights. The clock light does work but only with the headlights off, as soon as you turn the headlight switch on, the clock light goes out. It should come on or stay on and be usable with the dimmer controller.
 

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Discussion Starter #17
Read a forum on Toyota Nation dealing with a similar issue with a Tacoma where the problem was found to be a short inside the main Speedo Cluster. Went to wreckers today and got one, installed it and problem solved!
 

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the problem was found to be a short inside the main Speedo Cluster. Went to wreckers today and got one, installed it and problem solved!
Good job. Thanks for letting us know about the repair. I think this is the first time this problem has been reported here on RAV4World.

The difference between the "gear selector" light, and all the switches that I listed, is that current flows to ground through two different connections on the combination meter. ....... Try turning the dimmer rheostat to the indent position, as this bypasses the variable resistor, and sends a signal to the combination meter on a different pin. This should trigger a different response from the combination meter.
We were on the right track though. The "combination meter" I referred to is what you called the "Speedo Cluster". I was waiting for your reply as to what happened when the dimmer was placed into the "detent" position before making a diagnosis that the "combination meter was at fault".
 

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Read a forum on Toyota Nation dealing with a similar issue with a Tacoma where the problem was found to be a short inside the main Speedo Cluster. Went to wreckers today and got one, installed it and problem solved!
What about the mileage on the odo? Is the replacement pretty close to what yours showed?
 

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Discussion Starter #20
No its actually under just going to keep receipt and old cluster to show true mileage
 
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