- Thread starter
- #21
Purchased new switch from Toyota to no affect.
Rigid fog lights on 2024 LC
- Thread starter JDodge3
- Start date
Has to be a connector/wiring issue
- Thread starter
- #23
No solution yet. I replaced the switch to no avail. have to make an appointment for dealer to troublshoot. I keep checking back here to see if anyone has come up with a solution?
Any update on your end? I checked with the dealership; they've confirmed the problem but weren’t able to find the solution
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- #25
Nothing yet. They said I’d have to leave I a few days and I’d have to rent a car.
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- #26
Still nothing. If I hear, I'll post. Dealer said they would need it for a few days.
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- #27
Update. My LC was at the dealer for the last two days (Stamford Toyota, CT). They said that the fire radios and emergency equipment installed is causing interfierence with the data telling the lights to go from amber to white. anyone else havinng this issue without any addiitonal equipment, LMK.
Apologize up front for the long post.
That's BS, I'd ask them to call in one of their experts, not sure how many Toyota has?
If you turn the Radios off there can't be any RF interference, if your not actively transmitting there won't be any either unless you have a faulty receiver and its not in a metal box (but that would still be far fetched).
In the modern world this would be happening to allot of people if RF interference were the cause and it wouldn't be just the color change function that was affected.
Also your not the only one this has happened too. It would take quite allot of RF power to cause interference in a properly grounded and shielded system and dare I say you would be suffering from RF exposure if that were the case.
I have a 100 Watt transmitter system in my Tundra and no ill effects for over 10 years, it's not as advanced but still uses CANBUS and CXPI just like the 250. I'd buy a lottery ticket if the interference can constantly generate a proper and clean DC pulse width modulated signal to lock or prevent a function switch while also being able to not affect anything else using the same communication with a varying pulse widths to control other functions. Unless you pushing high power and your antenna wire has got shield or ground issues and is run directly beside any of the modules its highly unlikely its coming off the antenna through metal to get back to the modules. At what they are suggestion you should have radio interference for sure and possible the cars radar as well.
Anyway on to what I no of the fog circuit, that signal from the switch runs through at a minimum the Body Control module and then onto the Semi-Conductor Power Integration module (ECU), this module is in the engine bay passenger side fuse block Black rectangle. You can release the module by pressing the clips and lift it out to see the four connectors on the backside. You're looking for A86 connecter it is the first one inside the A85 connector which only has two wires on it (sorry don't remember from left or right) find the two wire connector and its the one next to it. You can inspect the wiring there to see if all pins look to be seated and unplug the connector to check for any damage or corrosion. I know for sure the fog system communicates over the CANBUS and CXPI communication lines and has to talk to the Headlight ECUs, the aforementioned module, Body Control Module, Two ECUs in the steering column and the DIM and is a fairly complex circuit but what is unclear is how the color change happens (never found a thing about it). But Toyota can command the fog lights to turn and off and I believe switch color in GTS+ (Can't remember if the color switch function exists or not) and signal trace from there. Shouldn't be hard to track down once forced on if possible. I'd guess since it turns the light off on the switch when switching and the switch has been ruled out that its not getting the repeat back from the Body control module after the button press to light the white backlight. 99% positive that the power to light the backlight is supplied by BCM. That is where I'd start if I worked for Toyota after doing the easy module swap from the engine bay and the already performed switch change out and possible swapping a fog light. I'm pretty sure the headlight ECUs play a role in the color change as well as when I was researching the fog light circuit for other purposes the A86 connector only has a power and ground for the foglights and other functions listed below.
A86 breakout is as follows: All power is CXPI communication which is Pulse width modulated DC, need and o-scope to read and all are variable 8V-14V square wave dc pulse.
Pin 1 Ground
Pin 2 Heater hot water pump power
Pin 3 Lo Wiper function power to wiper motor
Pin 4 Hi Wiper function power to wiper motor
Pin 5 Ground
Pin 6 Fog light power (Pink wire)
Pin 7 Unknown, maybe not wire installed can't remember maybe this is the communication line?
Pin 8 LH Headlight power
A87 pin 7 is the input CXPI communication line for the entire Semi-Conductor power integration module next one over from A86, and the comes directly from the Power distribution box (Part of the Body control Module).
If you can get ahold of the B9 or B10 connector pinouts you might be able to find out where the color changing function comes from, these are the two connectors at the foglights themselves (Either the Headlight ECU or Body control module like control the change over). Could ask Toyota to look up those connector pinouts as well as the terminals of the ecu for the body control module as that may help determine how the function operates. I tried during my research to find info on the headlight ECU but it only lists inputs to the headlight assembly and notes all internal operations are control by the ECU so no details on DRL, Turn signal, parking lights and all the other headlight functions or any outputs.
Maybe see if the dealer would swap the Semi-Conductor power integration module with one on the lot with color switching ability? That would further isolate the issue. I'd also ask that they plug one of your fog lights into a working model on the lot to rule out the fog lights, unlikely they have both failed together though unless they are the symptom of trouble and not the source. Probably safer for Toyota to swap any of your parts onto a working vehicle vice the other way round, less chance of killing known good components this way by not installing them into an unknown system.
Another help connector to have the pinout for would be the one attached to the switch itself, sorry don't have that to look at currently, but if its like the rest it is simply a simple backlit switch nothing special.
I suspect they are using the additional equipment as a cop out as the circuit is too complex even for most master techs, you need an Electronics and CANBUS expert technician or at least live phone troubleshooting with a competent local tech and the expert. Most dealer techs don't get much electronic or CANBUS experience as for most things a DTC is set and they just follow a procedure in TIS and GTS+. Probably will need to take it to corporate if your to reach resolution sadly. I had to have Volvo call in a tech once, had to wait 3 days for one of two West coast experts to arrive, 2 weeks later he nailed it down but first tried to blame all the aftermarket accessories.
He had to disconnect everything on the network as every DTC for the car was set and any OBDII connection activated the wipers on high and the codes couldn't be cleared or the network used to troubleshoot as a result, tracked it down to a failed power steering pump, not surprising on difficult in diagnosing when you have 5 separate network to deal with including 1 fiber network. Low and behold after pump replacement and all accessories reconnected the car has been fine ever since as well as prior to.
Good Luck
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- #29
I agree. They just gave up as it is above their acuity.
Hey Toyota tech here, i was dealing with this issue on a customer car. Toyota has almost no info on how the system works. But im here to say Replacing the left front fog lights fixes this issue. The one i worked on i ended up replacing both front fog light assemblies but i did notice by just replacing the left front which is a 6 wire connector vs 3 wire connector for the right side it did correct the issue. hope this helps
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