Flashing Brights Toggles Traction Control

Has anyone ever come across an electrical issue where the brights are linked to the traction control?

when I flash my brights or toggle the brights on/off it also toggles the traction control and auto LSD, and vice versa. When pressing the button to toggle traction control it flashes the brights.

I have installed an aftermarket front camera and switch that uses the stock head unit. It’s plug n play and connects directly into the back of the infotainment system. I suspected this may have something to do with my issue. Read something online about potentially because it’s sharing a grounding location with other systems under the hood. Disconnected the ground wire for the front camera system to test and the brights were still linked to the trac. Surprisingly the camera was still working perfectly though too, so maybe it’s accidentally grounding somewhere else it shouldn’t be.

Looking for any ideas or advice before I tear apart the dash again to investigate further. Really would prefer not to take apart the dash again if I don’t have to.

 

We have seen this before on a 17 but unfortunately the OP never came back to confirm whether I was right or not, still worth checking into that connector.

https://www.tacomaworld.com/threads/traction-control-lights.843224

 

Thank you! I’ll give that a shot. Is that fuse IA5 in the main fuse box under the hood? The diagram just looks a bit different than what’s under the hood on a 2023

 

looking at those connectors in the driver footwell, I do see one unconnected that could be IA5 but not sure. But, it doesn’t seem to have any connection where that would fit into nearby. It’s a bit larger than the port right in front of it.

 

Sorry I realize that was the wrong one, IA5 is the bottom one on that block. I unplugged IA5 and plugged it back in, issue fixed.

thanks for pointing me in the right direction!

 

That's definitely not IA5 that's unhooked, IA5 is a 26 pin connector.

 

Any visible moisture/corrosion in there?

 

Didn’t see any visible moisture or corrosion, but the issue did begin during a really wet and snowy time last spring so could’ve been the cause.

nevertheless, reseating the connection seems to resolved the issue. But we’ll see if it comes back again

 

In this diagram from the linked thread, how did you identify which connections relate to which features of the truck? With quick Google searching I was unable to find more info about what each connector relates to

 

Toyota does not provide much info on inline harness connectors other than location and pinout, we have to look at wiring diagrams to see what wires go to what pins of what connector.

Whenever I have an issue with 2 seemingly unrelated systems I always look what they have in common and start there.
In this case we have the headlight circuit affecting the VSC Off switch circuit.

So if we look at the ABS/VSC wiring diagram we see that the VSC Off switch circuit is a pull down input to the Skid Control ECU and it goes through IA5 on Pin 19 (Grey)


Now we look at the headlight wiring diagram for possible connections and we see that the control wire for the Dimmer relay also goes through IA5 at Pin 5 (Yellow), the relay is ground side controlled so the Body ECU supplies a ground to that wire to turn the Dimmer relay on when high beams are selected.
We know that grounding the wire from the VSC off switch turns off traction control therefore logic says that if something like moisture or corrosion were to allow voltage to "leak" across those pins we would have the exact symptom you describe.

 

@Dm93 you are a legend, thank you for this detail and explanation!

I can find the wiring diagrams online and this info will be super helpful in troubleshooting things down the road if I encounter other electrical problems.

 

Many moons ago I had a Fiat. At one point, it developed the ability to wipe the windscreen every time you hit the horn.

(I believe they'd blame this on AI, these days...)