Hello all,
Here is another hair-brained electrical modification I've been thinking a lot about since buying this 2012 Mazda5. I have a lot of words to gush here before I get to pictures and diagrams - this is my process for figuring out how to go about this - so bear with me here......(drunk)
My Subaru has the headlights/parking lights tied to the ignition circuit. If the lights are switched on and the key is removed, the lights go off. And then turn right back on with the key.
I prefer this arrangement because the headlights are on all the time and we just don't think about switching the lights on and off. This possibly has an effect on bulb life. But I prefer the quasi-daytime-running-light approach where safety through being visible to other drivers is higher priority than bulb life.
On the USA-spec Mazda5 for 2012, the headlights/parking lights are tied to a beeper alarm if the door is opened, key removed and light switch on. This drives me nuts because first up, we have to think about turning on the lights - since the cluster lighting is always on, this makes it appear initially that the headlights are indeed on.
And my biggest pet peeve, that when the lights are left on when getting out of the car, the beep alarm goes off. When I pull the key, I want EVERYTHING to shut down (well, expect dome lighting I suppose). Those of you in Canada don't have to think to hard about any of this since DRLs are standard. And those of you with the Automatic light sensor also don't have to think too hard about this either.
The cave-man response here might be "Well, just turn the damn light switch off."
But I believe we live in a more sophisticated world than that. I think headlights/parking lights should be turned on with the car running.
My first attempt to map out the solution is to tie a relay coil to the headlight switch. But Mazda, like many carmakers these days, elected to route the signal through the BCM (computer box). This is further complicated by the parking light circuit (TNS) being routed separately from the headlight circuit - both TNS and the headlights go through the BCM.
So I need to trigger two circuits simultaneously with a SPDT relay, or two SPST relays, or something else.
When the headlight switch is set to the second position (headlights+parking lights), the switch triggers the TNS and headlight circuits. Since there is no condition the headlights should be on WITHOUT the TNS loop, I figured I can one-way valve this with a diode.
For 2012, the headlight switch connector in the steering column is as follows:
Black - ground
Brown/Red - TNS 12V+
Red/Black - Headlight 12V+
Note that this is different than the earlier year models which have:
Black - ground
Brown/Red - TNS 12V+
Yellow - Headlight 12V+
I can trigger my relay coil with the windshield washer fuse (25amp). This fuse is not powered until the ignition circuit comes on. So it is a convenient place to trigger the coil (note that this is a great trigger point for many other electronic ideas!). As luck would have it, my fuse tap is for the larger (older) fuses - ah technology marches on. I can sort that out later - electrically I have tested this end of the mod.
The trick then becomes using the closed contactor in the relay to simulate the headlight switch position being turned on (TNS+headlight).
I placed a diode between the TNS and Headlight pins on the connector.....silver side (CATHODE) to the TNS. And the lead to the contactor is on the headlight side of the diode (the non silver side ANODE)
The good news is the headlight switch still operated correctly (it beeps when left on, ignition off, door open). And the headlights turn on automatically with the ignition.
The bad news is the parking lights (the TNS circuit) did not turn on.
I'm thinking at minimum, the diode might be backwards. But then maybe I can't do this with a single diode and a single relay anyway.......(uhm)
I was so bent out of shape after crawling around under both sides of the dash that I called it a night so I can sleep on it.:dodgy:
Any thoughts before I go at it again tomorrow morning?
Here is another hair-brained electrical modification I've been thinking a lot about since buying this 2012 Mazda5. I have a lot of words to gush here before I get to pictures and diagrams - this is my process for figuring out how to go about this - so bear with me here......(drunk)
My Subaru has the headlights/parking lights tied to the ignition circuit. If the lights are switched on and the key is removed, the lights go off. And then turn right back on with the key.
I prefer this arrangement because the headlights are on all the time and we just don't think about switching the lights on and off. This possibly has an effect on bulb life. But I prefer the quasi-daytime-running-light approach where safety through being visible to other drivers is higher priority than bulb life.
On the USA-spec Mazda5 for 2012, the headlights/parking lights are tied to a beeper alarm if the door is opened, key removed and light switch on. This drives me nuts because first up, we have to think about turning on the lights - since the cluster lighting is always on, this makes it appear initially that the headlights are indeed on.
And my biggest pet peeve, that when the lights are left on when getting out of the car, the beep alarm goes off. When I pull the key, I want EVERYTHING to shut down (well, expect dome lighting I suppose). Those of you in Canada don't have to think to hard about any of this since DRLs are standard. And those of you with the Automatic light sensor also don't have to think too hard about this either.
The cave-man response here might be "Well, just turn the damn light switch off."
But I believe we live in a more sophisticated world than that. I think headlights/parking lights should be turned on with the car running.
My first attempt to map out the solution is to tie a relay coil to the headlight switch. But Mazda, like many carmakers these days, elected to route the signal through the BCM (computer box). This is further complicated by the parking light circuit (TNS) being routed separately from the headlight circuit - both TNS and the headlights go through the BCM.
So I need to trigger two circuits simultaneously with a SPDT relay, or two SPST relays, or something else.
When the headlight switch is set to the second position (headlights+parking lights), the switch triggers the TNS and headlight circuits. Since there is no condition the headlights should be on WITHOUT the TNS loop, I figured I can one-way valve this with a diode.
For 2012, the headlight switch connector in the steering column is as follows:
Black - ground
Brown/Red - TNS 12V+
Red/Black - Headlight 12V+
Note that this is different than the earlier year models which have:
Black - ground
Brown/Red - TNS 12V+
Yellow - Headlight 12V+
I can trigger my relay coil with the windshield washer fuse (25amp). This fuse is not powered until the ignition circuit comes on. So it is a convenient place to trigger the coil (note that this is a great trigger point for many other electronic ideas!). As luck would have it, my fuse tap is for the larger (older) fuses - ah technology marches on. I can sort that out later - electrically I have tested this end of the mod.
The trick then becomes using the closed contactor in the relay to simulate the headlight switch position being turned on (TNS+headlight).
I placed a diode between the TNS and Headlight pins on the connector.....silver side (CATHODE) to the TNS. And the lead to the contactor is on the headlight side of the diode (the non silver side ANODE)
The good news is the headlight switch still operated correctly (it beeps when left on, ignition off, door open). And the headlights turn on automatically with the ignition.
The bad news is the parking lights (the TNS circuit) did not turn on.
I'm thinking at minimum, the diode might be backwards. But then maybe I can't do this with a single diode and a single relay anyway.......(uhm)
I was so bent out of shape after crawling around under both sides of the dash that I called it a night so I can sleep on it.:dodgy:
Any thoughts before I go at it again tomorrow morning?
