Rheostat/Dash Dimmer set on 'high'. Not able to adjust

So, just to say thank you to these forums for helping me choose a Tacoma over the other brands I was considering. Reading the help here went a long way in my eventual choice.

Having said that I bought a 2014 base model 4x4 manual 4 cylinder. Pretty bare bones. Was prewired for a reverse camera which I promptly bought and had installed within a couple of days after driving it off the lot. (Thank you all here for the help needed for that!).

I start looking around to see if there's any other prewiring I might be able to use to update my Taco. Popped the button blanks looking for wiring for fog lights (no luck) but did see this blue block:


I also noticed that my dimmer wheel that controls the dash lights did not dim. It was on Full. Dialing down the wheel had no effect. The lights are on through. So that's a plus. However, it's a 'new' (to me) truck and I want everything working. So looking online I find a used rheostat/dimmer switch. And it appears to be an exact 'mate' of the loose blue block behind the blanks.




Could this have come loose at some point, and if that's so would the lights be set to 'high' on my dash. Wouldn't they be 'off'? Perhaps the switch is bust and somebody did a bypass to enable dash lights to be on full, always?

I have a full history of the vehicle. It's been baby-ed, going into the dealership every few months for oil changes, tire rotations and all other maintenance. Nothing documented there, but obviously the last owner could have done something himself.

Wanting to avoid ripping off the dash cover. Already scratched up my 'new' Taco popping off the blanks


Any ideas?
And thanks!

 

Are you saying your dimmer switch was not hooked up?
Or that you did not have have a dimmer at all?

The blue plug looks right, but I can’t see the wire colors.

So you know how to read a wiring diagram?

 

I suspect the dimmer switch is not hooked up. I have the dimmer switch in place but it does nothing besides plug a hole in the dash.
Here's a picture of the wire colors:



My suspicion is that the blue block has become unsnapped from the back of the rheostat.

But I am not sure if that was the case why the dash light would still be lit up if the circuit has been broken.

As to reading a wiring diagram, I could not call that one of my strengths, certainly not proficient enough to risk damaging the Tacoma's electrical system if I foul-up.

I'm trying to avoid ripping out the console cover to check, but I am thinking it will have to be done.

 

Looks like the right one to me.
The colors match the diagram.
I’d plug it in and see what happens.

 

Going to grab a spare rheostat off of eBay and temporarily plug it in to see what happens before I rip the cover off. Hoping fuses will protect the system from any major errors on my part. If it works I'll fit it correctly. Thanks for the help!

 

Have you plugged the current dimmer in and tried it?

 

Do you have any other buttons like Foglights, or Traction Conrol?
Is, do they light up?

 

Do you have an aftermarket stereo?

If yes and the previous owner connected the Orange with white stripe wire for Illumination it probably blew the Rheostat. When this happens it has no dash lights. This is a known issue with many Toyota vehicles. If the rheostat is blown you can disconnect the rheostat and get dash lights back on full, they just will not dim.

Looking at what you have that appears to be the case.

IF So, I would pull the stereo and make sure the Orange and white stripe wire is disconnected and capped off Before Installing a new rheostat and blowing it up also.

 

Excellent post
I’ll have to keep this in mind, can’t say I’ve seen this.
I was hoping you or Muddin’ would jump in and have a look.

 

As to the aftermarket stereo, it appears to be the original entune system, the base version at that ( It has voice recognition but no button to initiate it! No apps, no GPS) So I can't imagine that it's been upgraded. Perhaps replaced? But the 'symptoms' I have do appear to match what you describe. The rheostat does not dim, but the dash light works and seems to be on full. There's is a loose connector behind the blanks, which seems to match the connector needed for the rheostat switch. I have yet to try to connect this connector with the rheostat as that would require the dismantling of the dash panels to access the rheostat/dimmer switch, which doesn't appear to be able to be pulled out of the fascia without access to the back on the rheostat switch, which is embedded in the fascia. (the photos I included of the rheostat/dimmer I found online. They are not my switch, which is still stuck in the dash)

Perhaps the radio was replaced, and this was not correctly installed. That seems odd, as the service history of the vehicle indicates that it's been well cared for with plenty of visits to the dealership every few months. The original owner seems not to have been a tinkerer, having all his service done at the same place. I would imagine if a new radio was put in it would have been the dealership that carried it out. Would they have screwed it up and then not fixed something so obvious? Who knows.

It does match your description though.

Don't suppose they connector simply fell out? Can't imagine that either.

Going to have to get those panels off aren't I?

 

Do you have any other switch?
Like Trac Control or Fog lights?
I believe I see one, in picture above.
Does it light up with the headlights ON?

 

No other switches in the area. The only things that light up are the main dash (speedo etc) and the AC/heating dials (3 of them). It's the base version of the vehicle. No Bells or whistles. No light on door window switch and things like that. No electric mirrors or similar stuff.

 

Like the one shown here?

 

@Taco-Jones

The symptoms do indeed match. And the wire colors match the drawing for the rheostat perfectly along with the wire locations. I don't know of anything else that connector could go to as the wiring is all related to the Illumination Circuit and Ground.

If i remember correctly it is possible to pry out the rheostat without removing the dash panels. Just be careful and don't screw up the panel while doing it. As you can see in your image above there is only a small friction clip at the top and bottom of the switch housing holding it in place. Get a couple of small plastic spudgers and pry at the top and bottom at the same time.

https://en.wikipedia.org/wiki/Spudger

If you get the rheostat out use a fishing loop to bring the connector up to the proper hole and connect the suspected problem rheostat if the dash lights go out it will tell the tale that the rheostat is indeed defective. Free test and it shouldn't do any damage.

 

I will give that a go thanks!
Although my last spudger test on the blanks left some damage. Not much and only I can see it, but I know it's there.
So if the rheostat is disconnected the dash light defaults to max?

 

If the rheostat is disconnected, the dash lights will be off, they don't have a path to ground.
Your rheostat is located in the switch blanks? I thought it was mounted higher in all the trucks.

 

Yes, my rheostat is located where you picture. However, the plug that it should connect to seems to have slipped down behind the blanks. On my vehicle, I have 3 blanks with nothing hooked up, just a blank space behind them. So if no path to ground and my lights DO light up (at full), then something has been changed. Perhaps the rheostat failed, they disconnected it and simply bypassed the switch? Those rheostats are very expensive new. 100-250 bucks I've seen quoted online. Which is nuts! There is no way that the dash light will work if the rheostat is simply disconnected? No gound, no light? Is that correct?

The reason I ask is that I was hoping for a simple fix by just reconnecting switch and connector. I suspect though that something else is going on, and I'm diving down the rabbit hole.

 

Does it look like there are any added wires? Maybe the rheostat was bad and they bypassed it. The switch is about $135 but maybe you can get one from a junkyard or used on eBay?

Here is the path to ground through the switch (the red line):

 

If you can find someone selling this, it might have the switch in it already. You'll have to take a chance on the rheostat being good.
https://www.ebay.com/itm/2014-TOYOT...BEZEL-55404-04080/183795966658?epid=656802070

 

That's a good find! And very useful to get a good look at the back of the panel. This could be an option but I think I'm going to have to take that panel off and see what's going on.