How to make foglights stay ON with highbeams ???
Jan 21, 2011, 07:57 AM
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How to make foglights stay ON with highbeams ???
Hey everyone. I recently added some rally lighting, and thought it would be pretty slick to run it off of the fog light switch (since I don't have fogs). It works great, but one little issue... the fogs shut off when the high beams are on. That's the time when I need the extra light! How hard would this be to change in the ECU, or any ideas for a work around that would still let me use this switch? I didn't really want to add an aftermarket switch inside, but I guess that would be the final option. Thanks for any ideas!
Jan 21, 2011, 08:41 AM
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^ I forgot to mention that I need to be able to have just high beams without all the rally lights too. That's why I initally thought of the foglight switch.
Jan 21, 2011, 09:13 AM
#5
I checked the ECU pinout and I don't see anything light control related other than the brake switch (which is for cruise control). I'm not sure if you are referring to the SRS/ETACS ECU though.
Nice light setup!
Please note, I'm not sure if it was the thought that the ECU controlled the switching, but I'm not sure this belongs in the engine management section.
EDIT: Is this your answer? https://www.evolutionm.net/forums/ev...s-anytime.html (CT9A, but the same circuit would probably work).
Quintouple ultra ninja edit: Sorry, looks like that link above never panned out. I'll keep it on the back of my mind...
And since you are from WI you might want to take note of this statute: https://www.evolutionm.net/forums/3049341-post9.html
Last edited by fostytou; Jan 21, 2011 at 09:40 AM.
Jan 21, 2011, 09:42 AM
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Thanks for the reply. If I could power it direct from the high beams, I wouldn't need to mess around with building a circuit (if that even works on the X). Anytime the rally lights are on, the high beams should be on, but I want to be able to shut the rally lights off as needed, and run high beams by themselves.
PS: Sorry for posting here, but it seemed to make the most sense as I thought this was ECU controlled.
PS: Sorry for posting here, but it seemed to make the most sense as I thought this was ECU controlled.
Jan 21, 2011, 09:49 AM
#7
Thanks for the reply. If I could power it direct from the high beams, I wouldn't need to mess around with building a circuit (if that even works on the X). Anytime the rally lights are on, the high beams should be on, but I want to be able to shut the rally lights off as needed, and run high beams by themselves.
PS: Sorry for posting here, but it seemed to make the most sense as I thought this was ECU controlled.
PS: Sorry for posting here, but it seemed to make the most sense as I thought this was ECU controlled.
Do you have HID or the standard lights?
If HID:
If you can find where the relay is for the high beam solenoid you might be able to divert some power / ground from it to the fog relay. We'd have to know if you are running all of the lights off the OE fog relay (which I think might not be the best idea... thats alot of extra power) or if you are running a seperate relay for them off of the factory relay.
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Jan 21, 2011, 10:41 AM
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Please read the post again as I edited it a ton of times as information came up.
Do you have HID or the standard lights?
If HID:
If you can find where the relay is for the high beam solenoid you might be able to divert some power / ground from it to the fog relay. We'd have to know if you are running all of the lights off the OE fog relay (which I think might not be the best idea... thats alot of extra power) or if you are running a seperate relay for them off of the factory relay.
Do you have HID or the standard lights?
If HID:
If you can find where the relay is for the high beam solenoid you might be able to divert some power / ground from it to the fog relay. We'd have to know if you are running all of the lights off the OE fog relay (which I think might not be the best idea... thats alot of extra power) or if you are running a seperate relay for them off of the factory relay.
Yes, I'm in WI, and these are for off road use only (ice racing). I have blackout covers if anyone gives me a hassle.
Jan 21, 2011, 11:07 AM
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Here's the contemplations:
The ETAS-ECU drives the stock fog light relay (pin 4 of connector C-312 from the ETAS-ECU). The fog light switch in the car runs through an ECU in the steering column, which talks to the ETAS-ECU which controls which lighting relays get energized. Therefore, the ETAS-ECU has final say over when a particular set of [stock] lights is on. In this car, we simply redirected the ETAS-ECU's fog light output to drive the new relay (used a new relay and wiring due to the higher current requirements than the stock fog light circuit).
It would be simple to set the new lights up to work off both the stock fog light circuit and the stock high-beam circuit, but that would cause them to turn on any time the high beams are on. Ultimately, the cleanest, coolest solution would be that the ETAS-ECU not shut off fogs when high beams are on.
In looking at the circuit diagrams again, it may be possible to get the fog light switch status and control the fog light relay, bypassing the ETAS-ECU. But it may require a bit of circuitry - not just simple wiring. I'm not sure what type of communication goes between the COLUMN-ECU and the ETAS-ECU or whether it's reasonable to get at the wire between the fog light switch and the COLUMN-ECU (looks like it might be all one unit).
The ETAS-ECU drives the stock fog light relay (pin 4 of connector C-312 from the ETAS-ECU). The fog light switch in the car runs through an ECU in the steering column, which talks to the ETAS-ECU which controls which lighting relays get energized. Therefore, the ETAS-ECU has final say over when a particular set of [stock] lights is on. In this car, we simply redirected the ETAS-ECU's fog light output to drive the new relay (used a new relay and wiring due to the higher current requirements than the stock fog light circuit).
It would be simple to set the new lights up to work off both the stock fog light circuit and the stock high-beam circuit, but that would cause them to turn on any time the high beams are on. Ultimately, the cleanest, coolest solution would be that the ETAS-ECU not shut off fogs when high beams are on.
In looking at the circuit diagrams again, it may be possible to get the fog light switch status and control the fog light relay, bypassing the ETAS-ECU. But it may require a bit of circuitry - not just simple wiring. I'm not sure what type of communication goes between the COLUMN-ECU and the ETAS-ECU or whether it's reasonable to get at the wire between the fog light switch and the COLUMN-ECU (looks like it might be all one unit).
Sorry for over complicating it.
Jan 21, 2011, 11:43 AM
#12
I'd recommend the switch blanks by your left knee on the dash (behind the OE fog / turn stalk). You can make it look reasonably good without permanently damaging anything, and its not visually way out there to put a switch in that spot.
It sounds like you know, but just make sure you use an accessory ground for the relay switch so that the lights won't stay on when the car is off (unless you want that).
Alternatively, there's bound to be some cheap, easy way to just completely bypass the ETACS ECU with some kind of a converter that changes the OE fog light switch's momentary to a fixed on/off to control the relay.
It sounds like you know, but just make sure you use an accessory ground for the relay switch so that the lights won't stay on when the car is off (unless you want that).
Alternatively, there's bound to be some cheap, easy way to just completely bypass the ETACS ECU with some kind of a converter that changes the OE fog light switch's momentary to a fixed on/off to control the relay.
Jan 24, 2011, 05:03 AM
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I was looking into completely bypassing the ETAS-ECU, but from the service manual, it looks like the switch is part of a single unit that contains the COLUMN-ECU, so cracking into that unit to get at the switch wiring would be quite invasive.
Over the weekend I designed a circuit that should intercept the ETAS-ECU's control of the fog light relay and leave the fog lights in whatever state they were in at the time the high beams are turned on. (i.e.: if the fogs were on, they'll stay on, if they were off, they'll stay off). It's plug-n-play inside the underhood fuse/relay box with no wire cutting. I just have to test the circuit once I get the parts for it.
If I get the design perfected, I'll post the schematics and parts list for others to use it - it should work well on VIII, IX, and X - I just wish I had thought of it when I still had my VIII. Right now it's looking like only $1-$2 worth of parts.
Over the weekend I designed a circuit that should intercept the ETAS-ECU's control of the fog light relay and leave the fog lights in whatever state they were in at the time the high beams are turned on. (i.e.: if the fogs were on, they'll stay on, if they were off, they'll stay off). It's plug-n-play inside the underhood fuse/relay box with no wire cutting. I just have to test the circuit once I get the parts for it.
If I get the design perfected, I'll post the schematics and parts list for others to use it - it should work well on VIII, IX, and X - I just wish I had thought of it when I still had my VIII. Right now it's looking like only $1-$2 worth of parts.
Jan 24, 2011, 05:14 AM
#14
read through this, https://www.evolutionm.net/forums/ev...ht-switch.html , I had the same question. i figured out how to tap into the wire harness and install a switch so you can turn them on ANY time you want. you may have to read though the whole thing since there is info spread out throughout the thread. been a while since i have done it but if you have any questions just let me know. good luck.
