How to diagnose dimmer switch?
11-19-2016, 06:23 PM
#1
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How to diagnose dimmer switch?
Trying to get my cluster lights to work on my 90' 4runner. All the "idiot" lights on the bottom work as well as the turn signals. Everything else is out. I removed the instrument panel and took a look at the bulbs. Most were burnt out but a few of them looked good so I went ahead and gave them power through a battery and they lit right up. Why would they not illuminate with the truck running? Are some of the bulbs on a series connection, and one bulb causing the other to go out as well? Could it be the dimmer switch is faulty, how would I diagnose that with a multi meter? And how do I check the connector to see if it's getting power? Just not sure where to stick the multi meter forks. New to electrical 
Last edited by mattyboi; 11-19-2016 at 06:34 PM.
11-20-2016, 05:31 AM
#2
With the Rheostat unplugged
You want to measure the resistance between pins 2 and 3 it should change as you move the dial
As the resistance increases the bulbs get dimmer
If this is open meaning a break in the circuit the lights do not ground so they remain unlit
You want to measure the resistance between pins 2 and 3 it should change as you move the dial
As the resistance increases the bulbs get dimmer
If this is open meaning a break in the circuit the lights do not ground so they remain unlit
11-20-2016, 09:02 AM
#3
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Bear in mind that Toyota's work DIFFERENT than most cars do.
In most cars the circuit is
+12v -- > Switch --> device (light bulb etc) --> ground
In a Toyota the circuit is
+12v --> device (light bulb etc) --> Switch --> ground
There are very good reasons for doing it this way, but its backwards from the way most people think about it...
So in your case - substitute the rheostat for the switch..
Make sure you are getting 12v at the supply side of the rheostat.
In most cars the circuit is
+12v -- > Switch --> device (light bulb etc) --> ground
In a Toyota the circuit is
+12v --> device (light bulb etc) --> Switch --> ground
There are very good reasons for doing it this way, but its backwards from the way most people think about it...
So in your case - substitute the rheostat for the switch..
Make sure you are getting 12v at the supply side of the rheostat.
11-21-2016, 01:29 PM
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So I removed the rheostat and there was no continuity at any of the positions I had it set, which tells me it needs to be replaced, or repaired if possible. With the vehicle off (key turned to ACC) the connection was getting 0V but with the car on 14V. Should there be power to the rheostat with the car on ACC mode? Or is not supposed to be getting power unless the car is running?
11-21-2016, 02:40 PM
#6
The tail light relay needs to be pulled in to close the contacts
Being in BC you have the Day Time running lights mandatory in Canada so your tail lights need to go through the Daytime Running Light relay if that is not working correct that might be your problem
If it is the Canada Version you need to have it running and the Emergency brake released to close the tail light relay
I am sorry I did not pick up on the BC before
Being in BC you have the Day Time running lights mandatory in Canada so your tail lights need to go through the Daytime Running Light relay if that is not working correct that might be your problem
If it is the Canada Version you need to have it running and the Emergency brake released to close the tail light relay
I am sorry I did not pick up on the BC before
