Instrument illumination lights not working

Tiny
RICHARD HOLLOWAY
  • MEMBER
  • 1996 NISSAN ALTIMA
  • 2.4L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 420,000 MILES
Just got the car so don't know how the lights acted while going out but it's the illumination lights and the shift indicator lights. It has a aftermarket radio so after checking all the fuse boxes. I pulled the radio and while it's a hack job it's hooked up correctly. I then pulled the dimmer roller took it apart and cleaned the contacts with isopropyl, still no change. I just replaced the cluster with a used one because the speedometer was out I was hoping that would solve my illumination light problem to but it didn't. I checked the dimmer pigtail with a multi-meter and with the black lead on the black wire I'm getting 12v on the two red/yellow wires and the red/blue wire. Any suggestions would be much appreciated.
Friday, January 17th, 2020 AT 5:56 AM

11 Replies

Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Okay. We need to go through this wiring diagram and check each one of these components to see what you have lights on and what you don't. This will help us identify the potential problem area. As you can see they all share the same 12 volt feed and the control wire. The fact that you have voltage at the switch just means we need to find why it is not getting to these components. Based on what you found with the radio, I suspect it is a wiring issue.
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Friday, January 17th, 2020 AT 5:35 PM
Tiny
RICHARD HOLLOWAY
  • MEMBER
  • 26 POSTS
Okay, so are all of those the components that are supposed to have back-light illumination? If so my problem is worse than I thought. I'll actually put a list together after work tomorrow but with the car running and the lights on, off of memory none of those things have ambient illumination.
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Friday, January 17th, 2020 AT 7:40 PM
Tiny
RICHARD HOLLOWAY
  • MEMBER
  • 26 POSTS
Okay. Glove box light- illuminated.
ASDC- not illuminated.
Main window/lock controls- not illuminated.
A/C controls- not illuminated.
Instrument cluster- not illuminated.
Ashtray-not illuminated.
Hazard Switch- not illuminated.
A/T device- not illuminated.
Rear window defrost-not illuminated.
Radio- is aftermarket.
Clock-n/a.

Basically it looks like the glove box light is the only one working.
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Saturday, January 18th, 2020 AT 5:29 PM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Okay. So you appear to have proven out the control switch by getting 12 volts on the red/blue and red/yellow but I just want to make sure that is accurate. If you are getting the 12 volts as shown below then I am wondering if this is as simple as a dimmer switch issue. The Red/yellow wire is basically the ground. It just has the dimmer in line. The way that works is as you move the roller it increases the resistance which will dim the lights.

Anytime you increase resistance after a load in a circuit like a bulb it causes the load (bulb) to use less voltage because it requires some voltage to get past the resistance and get to ground.

So if you have a bulb with no resistance after it then you will have full illumination from the bulb because you require very little voltage to get to the ground stud. However, if you increase that dimmer switch then that will require more voltage which means the bulb will get a smaller share of it and it will dim.

So if you have 12 volts on this wire then that dimmer switch is all the way up and is taking all the voltage from the bulbs and they are not illuminated.

If you notice as well, the glove box is the only one not on this dimmer switch. Even though you cleaned it, I suspect it is the issue.
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Saturday, January 18th, 2020 AT 7:44 PM
Tiny
RICHARD HOLLOWAY
  • MEMBER
  • 26 POSTS
Not sure if it matters but I have two red/yellow wires one red/blue and one black in the back of my dimmer. I'm assuming that just means that the red/yellow in the diagram is my red/blue?
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Saturday, January 18th, 2020 AT 8:24 PM
Tiny
RICHARD HOLLOWAY
  • MEMBER
  • 26 POSTS
Okay, I just double checked and with the roller in the full down and full up position. I'm getting 12v at all three wires both red/yellows and the red/blue. So if I understand that means I need a new dimmer switch.
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Saturday, January 18th, 2020 AT 8:51 PM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
This is not surprising that you have two red/yellow wires. More than likely this is due to the splice that I circled. This bulb that is in the switch is part of the illumination and controlled by the dimmer as well. So as you move the dimmer that bulb is effected as well.

If you have 12 volts no matter what, it appears that is not operating. If it were me, I would replace it based on what you are seeing.
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Sunday, January 19th, 2020 AT 9:55 AM
Tiny
RICHARD HOLLOWAY
  • MEMBER
  • 26 POSTS
Okay, none of the local parts stores have them in stock. I'm ordering one and I'll update with results when I get it installed.
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Sunday, January 19th, 2020 AT 12:31 PM
Tiny
KASEKENNY
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Sounds great. Let us know what you find. Thanks
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Monday, January 20th, 2020 AT 5:17 PM
Tiny
RICHARD HOLLOWAY
  • MEMBER
  • 26 POSTS
The part finally arrived today, installed it and now I have working illumination lights. Thanks for the help in figuring this problem out I really am glad it was a simple switch and not reining that I would have to chase down.
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Wednesday, January 29th, 2020 AT 9:49 AM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Great news. Thanks for the update. I am sure that info will help others that have a similar issue. Please come back to 2CarPros if need other info. Thanks
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Wednesday, January 29th, 2020 AT 5:36 PM

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