Wiring another high beam switch (in addition to the stalk)

[skyblue]

Wondering if anyone here has added a switch for their high beams, I'm wanting to add a foot switch for my left foot that does nothing else. I'm not very confident in decoding electrical diagrams though, I was hoping maybe someone here could point me in a direction. I was hoping I could do what I did for the cruise control and just insert two pins into the back of a connector (probably the column ECU connector). But I'm not really sure which ones to go into. I have a 2015 Mirage (hatch), without daytime running lights.

[allrock]

have you manage to find the wire that powers the high beam relay?i think you can tap on that to create a new switch.

[skyblue]

I sort of want to do it from the stalk side because then it will automatically turn off the standard beams, I don't know if it's good to have the standard and high beams on at the same time, might cause a problem or too much heat.

have you manage to find the wire that powers the high beam relay?i think you can tap on that to create a new switch.

Pretty good idea, however if I added a switch in that circuit and I flicked it while driving I'd be left with no headlights because the ECU wouldn't be communicated to that I've turned the HI beams off. If I do anything else like independently powering the relay I then end up with both HI and LO going at the same time, I'd need a switch that breaks one circuit and connects another with a single switch.



I think this will work, adding a double throw double pole ??? to the both relay circuits I can break the high beam circuit when I want to dim and reconnect the low beam with a connection to ground which will cause them to light up again.

[Eggman]

I sort of want to do it from the stalk side because then it will automatically turn off the standard beams, I don't know if it's good to have the standard and high beams on at the same time, might cause a problem or too much heat.



Pretty good idea, however if I added a switch in that circuit and I flicked it while driving I'd be left with no headlights because the ECU wouldn't be communicated to that I've turned the HI beams off. If I do anything else like independently powering the relay I then end up with both HI and LO going at the same time, I'd need a switch that breaks one circuit and connects another with a single switch.



I think this will work, adding a double throw double pole ??? to the both relay circuits I can break the high beam circuit when I want to dim and reconnect the low beam with a connection to ground which will cause them to light up again.

Attachment 21430

Any chance the ETACS ECU monitors the relay coils? Will disconnecting the relay coil from the ETACS ECU throw a fault code?

Past efforts with LED lighting has caused problems with the Mirage electronics. Proceed with caution.

[skyblue]

Any chance the ETACS ECU monitors the relay coils? Will disconnecting the relay coil from the ETACS ECU throw a fault code?

Past efforts with LED lighting has caused problems with the Mirage electronics. Proceed with caution.

It may well do, I should check for fault codes tomorrow, I did disconnect C-406 just now and turned to the key to ON, however C-406 must power the dash or something because it was all dark. I am slightly concerned that disconnecting the relays while underway might do "something" but I can't really think of why. All I'm doing is disconnecting one circuit (HI relay) and completing another (LO relay) with a double pole double throw switch, which is what I'm led to believe the ETACS does somewhere inside it anyway. How I'm wiring it should mean that when I'm switched one way I'm completely bypassing ETACS and when I'm switched the other I'm entirely back on ETACS, if that makes sense.

Anyway I found what I was looking for, I powered up both relays with no issues, C-406 is plugged into the ETACS which is often referred to the junction box in service documents which is what I'd call the fuse box (I had no idea ETACS was behind it), my fuse box on right wheel drive is located on the passengers side behind the glove box. I took some pictures, maybe others might benefit from seeing the location.






Anyone know what the transistors are for at the ends of the relay circuits, is it just a switch for the ETACS? is it something to do with the headlights turning off automatically when you get out of the car?

Why does the LO beam relay have a diode on it but the HI beam relay doesn't?

I wonder if you could go a step further and automate the double pole double throw switch with a light sensing transistor for automatic high beam.

[Eggman]

It may well do, I should check for fault codes tomorrow, I did disconnect C-406 just now and turned to the key to ON, however C-406 must power the dash or something because it was all dark. I am slightly concerned that disconnecting the relays while underway might do "something" but I can't really think of why. All I'm doing is disconnecting one circuit (HI relay) and completing another (LO relay) with a double pole double throw switch, which is what I'm led to believe the ETACS does somewhere inside it anyway. How I'm wiring it should mean that when I'm switched one way I'm completely bypassing ETACS and when I'm switched the other I'm entirely back on ETACS, if that makes sense.

It used to be that the headlamp switch controlled the relay coil direcly. With modern electronics, the switches act as an input into a computer which in turn controls the outputs. This gives a multitude of benefits, such as automatic control as you have suggested. It also allows monitoring the integrity of the circuits - the wiring and the device (either input or output.) To modify these circuits from their original design may or may not interfere with these functions. There's no telling until it's tried.

For example, a few forum members have switched out certain lamps with LEDs and caused strange operational problems with their Mirage. Lamps such as brake and turn signals are monitored for integrity - if a incandescent brake lamp burns out, the ETACS recognizes this and gives an error message (supposedly? I haven't seen one yet.) This is typically done by monitoring the overall resistance of the circuit - if the lamp burns out the circuit resistance increases to infinity, an open-circuit condition. The supervisory voltage used to monitor this circuit goes up, is sensed by the ETACS ECU and reports a problem.

When an incandescent lamp is replaced by an LED, the overall circuit resistance becomes much higher than what the ETACS ECU expects to see which becomes a problem for the ETACS. This problem has been reported here on the forum as the Mirage not running and/or a litany of dashboard warning indicators. On top of that, it doesn't always begin causing problems when they were first installed but sometime down the road at a very inopportune moment. And that's just from LED lamps in certain places. Cheap OBD adapters have also caused big problems.

All this just to say be aware of the changes you make and watch for subtle or worse problems down the road. With the changes you are making, you are putting voltage into a circuit that is designed to have only one source of energy to operate - adding another source could cause problems. Do you know what a new ETACS ECU costs to replace (parts & labor?)

Anyway I found what I was looking for, I powered up both relays with no issues, C-406 is plugged into the ETACS which is often referred to the junction box in service documents which is what I'd call the fuse box (I had no idea ETACS was behind it), my fuse box on right wheel drive is located on the passengers side behind the glove box. I took some pictures, maybe others might benefit from seeing the location.

The ETACS ECU is pretty small but does a lot.

Anyone know what the transistors are for at the ends of the relay circuits, is it something to do with the headlights turning off automatically when you get out of the car?

Not sure what transistors you are referring to. Could you be more specific or provide more details?

I wonder if you could go a step further and automate the double pole double throw switch with a light sensing transistor for automatic high beam.

Having an automatic high-beam malfunction would be a big problem to oncoming traffic. It might be one of the more difficult features to implement in any modern car.

But it's always fun to see what experiments might work.

[skyblue]

All this just to say be aware of the changes you make and watch for subtle or worse problems down the road. With the changes you are making, you are putting voltage into a circuit that is designed to have only one source of energy to operate - adding another source could cause problems. Do you know what a new ETACS ECU costs to replace (parts & labor?)

Not sure what transistors you are referring to. Could you be more specific or provide more details?

Having an automatic high-beam malfunction would be a big problem to oncoming traffic. It might be one of the more difficult features to implement in any modern car.

But it's always fun to see what experiments might work.

I know they aren't cheap whatsoever and I don't think you can just drop a new one in either, I think it has to be prepared so to speak. I appreciate your warnings.

I'm not following you when you say I'm adding a source of energy, from what I can see I'm connecting a circuit between the battery positive > relay > ground > battery negative, completely bypassing the ECU, my only slight concern comes from when I switch back to the original circuit, that there might be some shock, like a valve suddenly being opened, like a tap, but I can't see any difference to what I'm doing and what the transistor is doing inside the ECU.



See how there's a diode on the LO, and it's facing toward the ECU and ground, meaning it's allowing current into the ECU and ground but not out, I can't quite understand why power would want to push out of the ECU or ground toward the relay? I thought it might be reverse battery polarity protection but it's after the transistor so that doesn't really make sense.

You can see the transistors there, I guess they are the switches the ECU uses to connect/disconnect the relay circuits.

Yeah I won't be attempting the automatic high beam anytime soon, but I don't think it would require too much more work.

[Eggman]

I know they aren't cheap whatsoever and I don't think you can just drop a new one in either, I think it has to be prepared so to speak. I appreciate your warnings.

Yeah, experimentation can be fun but sometimes expensive.

I'm not following you when you say I'm adding a source of energy, from what I can see I'm connecting a circuit between the battery positive > relay > ground > battery negative, completely bypassing the ECU, my only slight concern comes from when I switch back to the original circuit, that there might be some shock, like a valve suddenly being opened, like a tap, but I can't see any difference to what I'm doing and what the transistor is doing inside the ECU.

Now just to be clear I have no inside knowledge of how that circuit is configured so there's that. But if an output circuit is configured to provide power to operate whatever it's intended to drive, it is providing energy to that device. If another source of energy is applied to that circuit external to the original OEM circuit, it may cause problems with that OEM circuit.

Take the brake, turn, or reverse lights for example - if the ETACS ECU is monitoring the integrity of those circuits, they expect to see a simple resistive load. If instead they see another source of electricity (energy) on them, that could confuse the supervisory circuit - or maybe not. There's one way to find out! But there's lots of evidence to suggest at least those three mentioned circuits are in fact supervised, mostly due to reports here on the forum of those who have replaced their original incandescent lamps with LEDs and started to have problems that basically rendered their Mirage undriveable.

See how there's a diode on the LO, and it's facing toward the ECU and ground, meaning it's allowing current into the ECU and ground but not out, I can't quite understand why power would want to push out of the ECU or ground toward the relay? I thought it might be reverse battery polarity protection but it's after the transistor so that doesn't really make sense.

You can see the transistors there, I guess they are the switches the ECU uses to connect/disconnect the relay circuits.

Not sure why the low beams got a diode and the high beam did not. But here's a possible explanation:
An inductive load such as a coil of wire (a relay coil) can produce a counter-electromotive force that can damage the driving circuitry. Here's how - when a coil is energized, it produces a magnetic field of whatever strength. When that coil is de-energized, that magnetic field collapses and in turn generates an electric potential (an ignition coil operates in this manner.) If there's any possible path for this energy, it will take it and sometimes cause damage. If they are used, (counter-electromotive force) CEMF diodes usually get placed across the inductive load (coil) so the energy can be dissipated at its source, but can also be placed at the driving circuit configured as a blocking diode keeping that spark from wrecking stuff.

Yeah I won't be attempting the automatic high beam anytime soon, but I don't think it would require too much more work.

So how would you set that up? Would you use ambient lighting to determine when to switch from low- to high-beams? How would you handle dimming your headlights for oncoming drivers?

[skyblue]

Yeah, experimentation can be fun but sometimes expensive.

Now just to be clear I have no inside knowledge of how that circuit is configured so there's that. But if an output circuit is configured to provide power to operate whatever it's intended to drive, it is providing energy to that device. If another source of energy is applied to that circuit external to the original OEM circuit, it may cause problems with that OEM circuit.

Take the brake, turn, or reverse lights for example - if the ETACS ECU is monitoring the integrity of those circuits, they expect to see a simple resistive load. If instead they see another source of electricity (energy) on them, that could confuse the supervisory circuit - or maybe not. There's one way to find out! But there's lots of evidence to suggest at least those three mentioned circuits are in fact supervised, mostly due to reports here on the forum of those who have replaced their original incandescent lamps with LEDs and started to have problems that basically rendered their Mirage undriveable.

Not sure why the low beams got a diode and the high beam did not. But here's a possible explanation:
An inductive load such as a coil of wire (a relay coil) can produce a counter-electromotive force that can damage the driving circuitry. Here's how - when a coil is energized, it produces a magnetic field of whatever strength. When that coil is de-energized, that magnetic field collapses and in turn generates an electric potential (an ignition coil operates in this manner.) If there's any possible path for this energy, it will take it and sometimes cause damage. If they are used, (counter-electromotive force) CEMF diodes usually get placed across the inductive load (coil) so the energy can be dissipated at its source, but can also be placed at the driving circuit configured as a blocking diode keeping that spark from wrecking stuff.

So how would you set that up? Would you use ambient lighting to determine when to switch from low- to high-beams? How would you handle dimming your headlights for oncoming drivers?

I don't think the ECU will be able to supervise, I think the only thing it could notice is that it's relay circuits are broken. I can't see anywhere else where the car has a monitor on the relay circuits. I might check for DTC's today.

Indicators are handled differently, the circuit goes to the ECU first and the relay is inside rather than it being in the engine compartment like the headlight relays are. I'm aware the ETACS has a field where you can change the voltage of the indicators, but it may do nothing just like several of the parameters that can be edited. I know indicators will flash faster when a bulb is dead, and that's got something to do with the resistance falling in the circuit but from looking at the circuit diagram for the mirage I'm not sure how that would happen, the relay must be different, and it seems to handle a lot more than the headlight relays.

I guess the diode is protecting the relay and anything backstream from that, which would be the battery, the high beam doesn't have one so I'm thinking it doesn't matter at all.





I believe this to be the "other side" of where those squiggles terminate in the schematic above (maybe). I actually thought I'd cracked this, I disconnected both HI and LO relays from the junction box connector and was going to wire them up to an earth from a ON OFF ON switch, then I realised that the taillights wouldn't be sync'd so I decided to bin that idea. I didn't actually check for DTC's but I didn't notice any complaint from the car when I was earthing both the relays or when I attempted to switch on the headlights and high beams from the stalk.

I then thought I might be able to just get into the back of the combination switch and do what I want to do before it's sent to the LIN/ECU but my combination switch is ribbon cables not individual cables like this which is a shame.


^ older style combination switch

^ribbon cables only, my style

I've been thinking of just buying dual filament LEDs and turning the high beams on when I want them and run the low beams the whole time, it's got to be cooler than running the stock bulbs at the same time I would have thought, but I'm not sure.

I might seek an experts opinion on whether or not my original plan would scramble the ECU.