Troubleshooting dash lights dimming and interior lights blinking

[TheyCallMeBT]

Hey folks. I have a 2008 Ford Expedition Eddie Bauer. I could use some help identifying an issue with the interior lights. See the video below.

The brightness of the green lights on the buttons and dash will go high to low (making a blinking like effect). Also, the actual interior overhead lights will blink on and off. Lately, the interior lights will not come on when I open the door (which they should). But they will sometimes come on if I turn them on manually by turning the dimmer switch for the interior lights all the way up.


I checked all of the fuses that could possibly correspond to this, and they were all fine. Someone recommended that I check all of the wiring in the passenger kick out panel. I did that and everything looked to be good.

I am thinking that it is the dimmer switch. The slider to the right of the headlights control. I ordered a new one on Amazon. Link below.

https://www.amazon.com/gp/product/B00H3U7008/

Any insight would be appreciated!

 

[stamp11127]

Welcome to the site.

It is better to diagnose vs tossing parts at a problem.

Can you read and understand wiring diagrams, have a dmm and know how to use it?

 

[TheyCallMeBT]

Thanks for the welcome, stamp! How do you suggest diagnosing the problem?

I have a decent understand of wiring diagrams (and can get assistance with it if needed). I do not know what a dmm is. My first thought was the computer that you plug in to see what codes are being thrown. Is that what you're talking about? Google wasn't helpful in trying to figure that out.

Also, I'm down the road from you in central GA!

 

[stamp11127]

Dmm is a digital multimeter.

I doubt you would get codes on that since it isn't part of the power train or have influence over the emissions.

I'll take a look at the diagrams later today, not sure if I have the 08's. If not we can see if the 07's are the same.

 

[TheyCallMeBT]

Oh yeah-- had to look up a photo-- but I've got access to one of those. My father is a general contractor, so he has at least one. And he can give me a hand with it, too.

I really appreciate you taking a look at the diagrams for me!

 

[stamp11127]

I don't have the 2008 diagrams but I've looked at the 2007. You have your work cut out for you.

One thing to check is if both the dash lights and interior lights both flicker at the same time.
Ford has multiple splices for these circuits but feed off one fuse in the smart junction box.

I'll need an email address to send the diagrams to. There is going to be quite a few of them - wiring, component locations and pin outs for the connectors & splices.

 

[bobmbx]

I would concentrate my first efforts around the dimmer switch. Try to remove it from the dash (hopefully it'll pull straight out). Inspect the wiring harness to the switch and the contacts at the switch for scorching.

 

[stamp11127]

These are electronically controlled lights using FETs (field effect transistors). There is a chance the dimmer switch has poor contacts and is sending low & high signals. There is also a possibility that the sjb (smart junction box) that contains the FET is having problems.

Meter time...

 

[Muddy Bean]

Just another data point: my Toyota Land Cruiser had the blinking interior lights issue. It was just worn door switches. Not sure if that’s your issue on the interior lights blinking but it may indeed be separate from your dash lights blinking. Two separate issues.


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[TheyCallMeBT]

I don't have the 2008 diagrams but I've looked at the 2007. You have your work cut out for you.

One thing to check is if both the dash lights and interior lights both flicker at the same time.
Ford has multiple splices for these circuits but feed off one fuse in the smart junction box.

I'll need an email address to send the diagrams to. There is going to be quite a few of them - wiring, component locations and pin outs for the connectors & splices.

Thank you! You can email them to me here.

(sent via PM)

I don't think that the dash lights and the interior lights flicker at the same time. But I'll check.

I would concentrate my first efforts around the dimmer switch. Try to remove it from the dash (hopefully it'll pull straight out). Inspect the wiring harness to the switch and the contacts at the switch for scorching.

The dimmer switch gets here today. It was only $10. The swap out looks to be pretty easy. So I'll try that before getting to the more complicated stuff.

Just another data point: my Toyota Land Cruiser had the blinking interior lights issue. It was just worn door switches. Not sure if that’s your issue on the interior lights blinking but it may indeed be separate from your dash lights blinking. Two separate issues.

When you say door switch, do you mean where you control the locks, windows, etc. on the door? If so, is that where the control for the interior lights was? It's been a year since this has been going on, but it SEEMS like these two issues started at the exact same time.