Cab switch backlights blinking with turn signal

Hello,

I recently noticed that when I use my turn signals (while the headlights/running lights are off) my cab lights blink with the turn signals. The backlighting on pretty much everything in the cab.

I have a 2014 with OEM LED headlights installed with a Headlight Revolution wiring harness. Have had that installed for the last 4 years with out issue.I have checked the fuses and what wiring I can currently see. Anyone have any ideas? I don't see any rodent damage although I have not crawled under the truck yet.

Thanks!

 

Does it do it with the hazard 4-ways as well?
But it doesn't do it when the headlight/running lights are on?

 

Does it with the hazards on. If The lights are on in it does not flash however. My DRLs are always on.

 

Ground problem...

 

Also what I think, Just not sure where to start with tracking something like that down. I am also not the most savvy with electrical stuff.

 

Not a fan of Headlight Revolution anything, but it is odd that it has worked properly for 4 years.

So you have not recently replaced any bulbs in the front or rear lights?
Replaced halogen bulbs (turn signals, parking lights) with LEDs or anything like that?

As others have stated something is grounding the dash illumination when your turn signals are on.

The only connection between the two I can think of is in the combination meter.
But they don't really 'connect'.

There have been a few threads over the years about wiring being crushed under the bed that caused issues like this..

Good luck..

 

Also are you sure the outside parking lights are not flashing along with the dash lights?

 

Start with the body grounds under the hood beside the battery. Then the grounds from the motor to the cab. Just for the heck of it, clean the battery terminals.

 

No sir, No more light replacements since the head lights

 

Yes. I checked to see what was flashing when the turn signals are engaged

 

Thank you. I will check it and clean the battery

 

Checked everything mentioned and cleaned the battery with no change. However, I did find a squirrel nest! Little bastard was under the engine cover and chewed up all the foam under there with a bunch of acorns! I cleaned that out and didn't see any wiring damage.

 

one of my LED brake lights was out.....

 

Was that the root cause??

 

i guess so, Unless replacing that caused something else to break where the cab lights don't work at all. Seems kinda weird to me.

 

Definitely odd. Fingers crossed that was it & only happy days ahead

 

yeah odd. Second question for everyone. Does anyone else have backlighting on there dash,AC controls and other factory switches? Mine is off completely however I remember there being lighting without the head lights on

 

Alright so I'm not positive its the tail light bulb. I have had these LED light bulbs for 3 years now and no issues until lately. When the bulbs get swapped for regular incandescent bulbs the back lighting goes out completely. When I put the LEDs back in the back lighting comes back, but so does the blinking with the turn signal.

Anyone got any ideas? Checked what fuses seem appropriate and they are fine

 

is there a backlighting fuse??

 

Seems the LEDs are grounding something on the dash lights when the turn signal is on.
Or they aren't getting their own proper ground and are grounding thru something else in the wiring.
Odd it only happens with the LED bulbs.

When you install the rear turn signal incandescent bulbs do the back lights (I'll call them dash lights) work as normal?
Only on when the parking/headlights are on?

Dash lights should only be on when the parking/headlights are on.
Except for the one backlight of the display screen that is on with the dash lights off (but can also off depending on the dimmer setting) and is dimmable when the lights are on..

The dash and parking lights are somewhat on the same circuit.
That is why I asked if the parking lights were also flashing.

So when the turn signals cause the dash lights to flash, none of the exterior lights are flashing as well?
Are there any issues with the parking lights?

The odd thing is that the rear turn signals have no direct connection with the dash or parking lights.
The front signals share the bulb with the parking lights and DRLs.
But none of that matters if the parking lights are not flashing with the dash lights.

There is a PANEL fuse, but your dash lights wouldn't come on at all if blown I would think.
It wouldn't hurt to check it, that might be the issue.
It should be under the dash in that fuse box.






I'm perplexed about what the problem is, that is isn't the outside lights flashing..
I see you found other threads on the problem but no one posted any solutions.
Although one said is was a grounding issue.
Did you test your rear turn signal sockets for proper ground with a DMM?

I think I mentioned crushed wiring under the bed or spare tire, but I think that would make the parking lights flash as well.

 

I think this could be aground issue also just not sure how to track it down.

Only LED lights on the rear are the back up and brake lights, Turn signal bulbs are not.

none of the exterior lights flash also, just the activated turn signal

I have not tested the grounds as I don't know how or have the tools.

yeah I am confused also as I have had these LED bulbs for 3 years with no issues until recently. I will check the panel fuse. Thank you for the reply and info!!

 

PANEL fuse is fine

 

I thought the LED bulbs were the turn signals.
That changes everything I was looking up.
Makes it even more odd the parking lights aren't blinking.
As well that they've worked fine for 3 years.

Are any other bulbs LED?
Front turn/parking/DRL?

I think you have a dirty socket, front or rear, a bad ground connection, or a bad wire somewhere.
Maybe take apart all your headlight and taillight connectors/sockets and make sure they are clean.
Spray them with contact cleaner, you can also find it at Lowes or auto parts stores...

$9 CRC 05103 QD Electronic Cleaner -11 Wt Oz

Amazon.com: CRC 05103 QD Electronic Cleaner -11 Wt Oz : Industrial & Scientific

You'd need a digital multimeter to check the ground.
Even a cheap one is handy to have around the house.

$19 AstroAI Digital Multimeter, Voltmeter 1.5v/9v/12v Battery Voltage Tester Auto-Ranging/Ohmmeter/DMM with NCV Function, Accurately Measures Voltage Current Amp Resistance Capacitance

AstroAI Digital Multimeter, Voltmeter 1.5v/9v/12v Battery Voltage Tester Auto-Ranging/Ohmmeter/DMM with NCV Function, Accurately Measures Voltage Current Amp Resistance Capacitance: Amazon.com: Tools & Home Improvement

$13 AstroAI Digital Multimeter Tester 2000 Counts with DC AC Voltmeter and Ohm Volt Amp Meter; Measures Voltage, Current, Resistance, Continuity and Diode, Blue

Amazon.com: AstroAI Digital Multimeter Tester 2000 Counts with DC AC Voltmeter and Ohm Volt Amp Meter; Measures Voltage, Current, Resistance, Continuity and Diode, Blue : Tools & Home Improvement

It would be step 5 in this link.
How To Test A Tail Light Socket With A Multimeter | Storables



I found a few articles that had your issue and that it worked fine with incandescent bulbs but not LEDS.
Most of them ended up being a ground issue.

If you want to try it, I'll post this info since I have nothing better to do.
I'm sitting at home after surgery so I can't do anything else.

Set your DMM on continuous or continuity put the cables in the appropriate plugs on the DMM.
You connect one cable lead to the ground of the socket, the other to a vehicle ground (bare bolt or unpainted metal).
Generally, most Toyota ground wires are white with a black stripe.

The truck doesn't need to be on or running to check the grounds.

Rear turn signal sockets are R13 (left) and R14 (right).
They are basically the same socket only 2 wires


Left, Pin 1 red/black stripe wire is power. Pin 2 white/black stripe wire is ground.
Right, Pin 1 Red wire is power. Pin 2 white with black stripe wire is ground.
You'll touch one DMM lead to pin 2 of the socket and the other to an unpainted metal bolt or part.
The meter should make a sound to confirm good ground.




Brake/parking light connector Left is R5 right is R4



The ground wire will be the white/black stripe wire in pin 2



Front turn signals left A12 right A13


Ground wire pin 2 white/black stripe.




The only connection between the dash lights and the turn signals in the Combination meter and even then there is no rear direct connection.

 

I know you have an HR adapter, but maybe @iHacker might have some input on this.
Most of us use his harness for the 2018+ OEM LED headlight upgrade...

It may have nothing to do with the headlight adapter, but @iHacker knows his stuff and might have some insight...

 

THANK YOU! Everything on the front except the turn signal is LED. Bought new LED light and the wiring harness from HR in 2022. Everything worked fine. On the rear the only bulbs that ARE LED are the brake lights and back up light. Again, had these for years with no issues.

 

Changing all the bulbs in the front and rear to see if that changes anything. Chased all the wiring from the rear lights to the engine bay with no problems found. Getting frustrated and thinking about taking it to a local dealership