Dash cluster backlight not illuminating, multiple lights out on dash.....dimmer switch? (1 Viewer)

[Francis K]

When my truck came back from the stereo shop recently the backlighting on the cluster wasn't illuminating. I needed to go in there and replace everything with LED's anyway I figured they just left something unplugged. Got everything out, switched out all the bulbs for LED's and was ready to rock. My half a banana mechanic ass was feeling pretty good about myself until I hooked everything up to test it, still not backlight and multiple indicator lights not working.

Is there a way to test out all the dash lights? Check to see what is working and what isn't?

My shift indicator lights work, my "cruise" light works, signals work, check engine works and door ajar works.

Seat belt light doesn't work, diff lock lights don't work, again back light doesn't work, 2nd doesn't work and od off doesn't work.....I'm sure there are others I can't test.


The tail lights work so it's not the fuse and the dimmer light switch looked to be in rough shape, plus I found an unplugged connector not sure what it's for, see pic attached. It can't possibly be that many bad LED's and of course the backlight wasn't working previously so I'm thinking it's the dimmer switch but not sure if those symptoms would account for that.....what do you guys think?

 

[Francis K]

Okay, now I'm thinking the polarity may be the issue with some of the bulbs. Is there a way to test them or know if I installed them on the right side?

But regardless that wouldn't address that dash illumination issue.....

 

[DivByZero]

I'm suspecting a bad ground, but really this is the point where I'd be getting a multimeter and a wiring diagram and probing. Forget the multitude of issues right now, just pick one thing and diagnose that. If the problems are related, it'll become apparent from diagnosing one of them.

If you don't have a multimeter, this will be hard. If you do, start checking for 12v and continuity to ground.

 

[DivByZero]

Wait, just realized I misread your OP as to what the problem is. So yes, the LED bulbs are directional. Diodes only allow power flow one way, unlike a globe which doesn't care about polarity. So all the LED lights that aren't working are in backwards. Easiest way to test is with a multimeter again, with that you can test which direction allows power flow using the Ohms setting. But hopefully the LEDs are marked in some way and you can see them visually. The other problem is, I don't think the cluster itself has polarity marked on the sockets (didn't matter for globes afterall), so you'll have to do a bit of tracing or checking with the EWD to see what's what. Or just flip the ones that aren't working until everything works again.

That leaves you with your problem of the backlight on the cluster not working. Yes, the dimmer switch could be involved, but you'll have to break out the multimeter to trace it.

 

[Francis K]

Wait, just realized I misread your OP as to what the problem is. So yes, the LED bulbs are directional. Diodes only allow power flow one way, unlike a globe which doesn't care about polarity. So all the LED lights that aren't working are in backwards. Easiest way to test is with a multimeter again, with that you can test which direction allows power flow using the Ohms setting. But hopefully the LEDs are marked in some way and you can see them visually. The other problem is, I don't think the cluster itself has polarity marked on the sockets (didn't matter for globes afterall), so you'll have to do a bit of tracing or checking with the EWD to see what's what. Or just flip the ones that aren't working until everything works again.

That leaves you with your problem of the backlight on the cluster not working. Yes, the dimmer switch could be involved, but you'll have to break out the multimeter to trace it.

Thank you sincerely for the reply, yea I’m going to pick up a multimeter today and figure out how to test the dimmer. I jumped the gun and already ordered one but it was super cheap so that works.

As for the bulbs, I saw you can test them with a 9v battery which I will do to make sure they are all working at least but for the polarity it’s just going by trial and error. It is what it is that’s going to be tedious but I’ll get it done, then the problem becomes that I can’t test all the lights so I’m going to have some that I’m just guessing if they work or not….that’s not a good situation.

 

[Francis K]

Picked up a multimeter set it to diode and tested out some of the LED's, all the little guys work find but I can't get the T10's to light up....I tested 10 of them. That can't be right, the product has over 3k reviews on Amazon with 4.5 stars....I'm the one who got "lucky" to have a bag of 20 where none of them work. I tested them on my courtesy lights and they all work, no idea why I couldn't get them to work with the multimeter.

Now I'm at the polarity issue, reading through the entire "definitive LED thread" I'm shocked so few people were talking about figuring out the polarity. I can't test every light on the dash so I'm of them I'm just going to be guessing they work, don't like that at all.

Still leaves the issue of the backlights not working, I'm completely new to this stuff how do I test the dimmer switch with the multimeter?

 

[Francis K]

Picked up a multimeter set it to diode and tested out some of the LED's, all the little guys work find but I can't get the T10's to light up....I tested 10 of them. That can't be right, the product has over 3k reviews on Amazon with 4.5 stars....I'm the one who got "lucky" to have a bag of 20 where none of them work. I tested them on my courtesy lights and they all work, no idea why I couldn't get them to work with the multimeter.

Now I'm at the polarity issue, reading through the entire "definitive LED thread" I'm shocked so few people were talking about figuring out the polarity. I can't test every light on the dash so I'm of them I'm just going to be guessing they work, don't like that at all.

Still leaves the issue of the backlights not working, I'm completely new to this stuff how do I test the dimmer switch with the multimeter?

Alright got everything working that I could, the only ones I couldn't get going were the seat belt light which is no big deal and the center diff lock. I can hear the center diff lock engaging but no light on the dash, the CDL worked previously and I even put the stock bulb back in but no joy.....

What's left if the backlights, trying to figure out how to test the dimmer now hoping thats all it is....

 

[Francis K]

Oh also just in case it helps someone else I was able to get most of the indicator lights to work by using new sockets, apparently that was the issue with a lot of them.

 

[Francis K]

Okay so how the hell do I test the dimmer switch with a multimeter? No idea how to do this crap getting quite an education here!

 

[ajax1]

Does the abs come on when you push the cdl button or shift to low? Could be the switch in the tcase or plug, you can jump the plug and see if that lights up the dash, if it does then the switch in tcase is bad or dirty. If still no light you have no bulb or bad wiring. Switch is on front pass side of the tcase, 27mm wrench to remove it.

 

[Francis K]

Alright I did all I can do, I changed every light in that pig. The last one I couldn't sort out was the floor shifter it's a really tight fit for the LED in the socket, the LED's I picked up appear to be very slightly wider than the stock bulbs. I got one in that flickered and then nothing, tried a bunch more and no light. Even tried a bunch of stock bulbs I pulled from various places and nothing I'm thinking I did some damage to it somehow, I gave up on that one might revisit it in the future but frustrated with that because that was one I really wanted working.

Can't figure out how to test the dimmer, hopefully the new one on the way solves the backlight issue.

 

[Dusten]

Alright I did all I can do, I changed every light in that pig. The last one I couldn't sort out was the floor shifter it's a really tight fit for the LED in the socket, the LED's I picked up appear to be very slightly wider than the stock bulbs. I got one in that flickered and then nothing, tried a bunch more and no light. Even tried a bunch of stock bulbs I pulled from various places and nothing I'm thinking I did some damage to it somehow, I gave up on that one might revisit it in the future but frustrated with that because that was one I really wanted working.

Can't figure out how to test the dimmer, hopefully the new one on the way solves the backlight issue.

A dimmer is a variable resistor. So you measure resistance on it. It will increase and decrease as you move it.

 

[flintknapper]

A dimmer is a variable resistor. So you measure resistance on it. It will increase and decrease as you move it.

^^^^^

This.

Very simple to test a dimmer/VR/Potentiometer.


Just set a digital multi meter to the Ohm setting, connect it to the dimmer. Move the knob and look for a smooth transition in the Ohm reading (greater or lesser reading).

 

[flintknapper]

Alright I did all I can do, I changed every light in that pig. The last one I couldn't sort out was the floor shifter it's a really tight fit for the LED in the socket, the LED's I picked up appear to be very slightly wider than the stock bulbs. I got one in that flickered and then nothing, tried a bunch more and no light. Even tried a bunch of stock bulbs I pulled from various places and nothing I'm thinking I did some damage to it somehow, I gave up on that one might revisit it in the future but frustrated with that because that was one I really wanted working.

Can't figure out how to test the dimmer, hopefully the new one on the way solves the backlight issue.

Floor shifter lighting should be a wedge bulb/LED. First check that you have power at the SOCKET. A simple test light will accomplish that and also show the polarity of the socket. Wiggle the wiring at the socket to see that you don't have an issue with the wiring or socket itself.

Test the bulb/led you intend to use with a 9 volt battery and test leads before installing. I do this with ALL 'LED's' before installing them to insure they work and determine polarity beforehand.

 

[Bsteimel]

Floor shifter lighting should be a wedge bulb/LED. First check that you have power at the SOCKET. A simple test light will accomplish that and also show the polarity of the socket. Wiggle the wiring at the socket to see that you don't have an issue with the wiring or socket itself.

Test the bulb/led you intend to use with a 9 volt battery and test leads before installing. I do this with ALL 'LED's' before installing them to insure they work and determine polarity beforehand.



View attachment 2920389

I replaced the bulb and it lights up but my shift indicator looks horrible the black portion is coming off. Has this happened to anyone else? Does it need a clean? Do i need to repaint the black portions? Sorry to hijack the thread but I was trying to take advantage of the same pictures.

 

[Francis K]

Just wanted to update in case anyone is stuck with this in the future, the new dimmer switch fixed EVERYTHING, the floor shifter, the diff lock switch....every light that wasn't lighting up....