dash cluster backlight brightness

[ira11y]

Could someone with an SR5 measure the resistance values please, or if your in the hills district sydney I can meet up and nut it out, should only take half an hour to chase and measure. I am looking to see if a unit from the states will work (= prettier than the 80's trim pot and should work) but need to confirm the resistance values.

My thoughts are that the ECU is looking for a precise change to the resistance, using any old rheostat doesn't work because its chasing a specific value to allow the voltage step. I the value falls outside the ECU's expected parameters it will assume either a fault or normal state and be shunting to full earth. hence why you get max light level with the plug in or out.

I have already tried throwing some resistors I had laying around across the pins with no luck. Also tried a couple of different rheostats from Corolla and Prado, they don't work either.

There must be someone close by with a 5 that will let me at their switch

[ira11y]

Found some info reading the GSIC data

C8 = Connector Plug 8, connects to combination meter
-9 = pin 9 on C8

NOTE:
*1: 1TR-FE, 2TR-FE
*2: w/o Airbag
*3: w/o ABS
*4: w/o Rheostat
*5: w/ Rheostat

C8-9 - Body ground*4
W-G - Body ground
Ground
Always
Below 1 Ω
C8-9 - Body ground*5
W-G - Body ground
Rheostat signal
Rheostat knob fully turned to left position
702 Ω
C8-9 - Body ground*5
W-G - Body ground
Rheostat signal
Rheostat knob fully turned to right position
Below 1 Ω

so effectively there should be no reason why a basic trim pot with the range 0.5 - 702Ω shouldn't work.

The reason some of the other rheostats I have tested aren't making an impact is because they are a lot narrower in range, for example an AE10X Corolla dimmer only has a range between 0 and 4.5Ω. Given this is a 4 step rolling switch as opposed to the SR5 constantly variable pot I can see a way to make it work is to simply crack open the switch and add bigger resistors. I think I will order the switch from the states and give it a crack now I understand the range. So much easier to work it out when the numbers are clear

[boxhead55]

Easy