No OE DRL, want fog to be DRL read this

[swede]

Yeah all of your suggestions probably should work but, there's a a big but in here

I also want my perifier (spelling) lightning to work when I hit my RKE as designed, with my diagram it should work on the fog lights. And the DRL turned off when put in park.

And the fog will work on the switch as it was intended to do because I just splice in on the fog lamp wire, see first post with pics.



EDIT: Attached is a pic of a stock OEM relay, low beam HL and cooling fan uses the same kind of relay 15016745. Notice the complexity of the internal on the relay, this is not a standard relay. Looks like it have a PWM converter built in the relay.

 

[swede]

IT'S WORKING!


But first I was like wtf I give up, couldn't get it to work when I turned on the ignition or started the truck

The perimeter lights worked as designed on fogs but no fogs when truck was running

I'm so so f..ing stupid, after pulling my hair for a while finally the quarter fell down - I needed to pull my truck out of park and it worked as I designed it.

First picture is on relay 1 I have installed under rear seat, basically it controls if the power goes to factory HL relay or to my extra installed HL (fog) relay depending on what the light sensor tells the BCM to do.

Second picture is my extra OEM HL relay mounted on inner fender well and controls the fogs as a DRL and perimeter lightning.

My fogs still work on factory fog light button. Finally finished with my fogs as DRL the way I wanted it.

 

[Sib]

Clean set up. Glad you got it working.

 

[Tiggerr]

Glad you got it working the way you wanted!

 

[Mounce]

EDIT: Attached is a pic of a stock OEM relay, low beam HL and cooling fan uses the same kind of relay 15016745. Notice the complexity of the internal on the relay, this is not a standard relay. Looks like it have a PWM converter built in the relay.

It's a solid state relay. The BCM creates the PWM signal and sends it to the coil pins on the relay to handle the high current (draw of the bulbs) switching.

 

[swede]

It's a solid state relay. The BCM creates the PWM signal and sends it to the coil pins on the relay to handle the high current (draw of the bulbs) switching.

Sorry don't know the difference between a solid state relay and a non solid state?

I tested with a normal 12 volt automotive relay first but that didn't work due to that the PWM signal is neither positive 12 volt DC current nor negative 12 volt DC current.
When you look at the outside of the relay you can see it uses both diode and resistor inside, most likely to convert the PWM signal to a DC current. Correct me if I'm wrong ok?

 

[Mounce]

The PWM signal is in DC current. I don't know the technical difference between solid state and regular relays either. The regular relay likely couldn't handle it due to the fast on/off switching.

 

[swede]

The PWM signal is in DC current. I don't know the technical difference between solid state and regular relays either. The regular relay likely couldn't handle it due to the fast on/off switching.

The PWM signal isn't a DC current, didn't you see the pictures I posted from my DMM? And the video Mooseman put up?

 

[coolasice]

The PWM signal is in DC current. I don't know the technical difference between solid state and regular relays either. The regular relay likely couldn't handle it due to the fast on/off switching.

Solid state uses transistors to stop/pass the electric current while regular relays rely on a coil to be energized and mechanically move a arm to close the contacts.

 

[coolasice]

The PWM signal isn't a DC current, didn't you see the pictures I posted from my DMM? And the video Mooseman put up?

The pwm is in fact dc. The signal is switching so fast the multimeter cannot read it properly and will show up as ac.

 

[swede]

The pwm is in fact dc. The signal is switching so fast the multimeter cannot read it properly and will show up as ac.

I stand corrected and will go to my corner with my stupid hat on for the rest of the evening

I thought they all were different:

DC = direct current, PWM = Pulse Width Modulation and AC = Alternating current

But I was wrong and I'm the first one to admit it, sorry Mounce

 

[Texan]

To add fuel to the fire. What I remember from my military training as
a ground radio repairman (long time ago).

AM Amplitude Modulation (sine wave) AC and upper & lower side bands
FM Frequency Modulation (sine wave) AC
PWM Pulse Width Modulation (sine wave) AC IIRC

I would guess that the DRL is a pulsed DC current.

 

[coolasice]

Pwm can be used to produce ac waveforms(thats how dc-ac car inverters and ups systems work), in the case of controlling ssr(solid state relay) it is only dc.

 

[Mounce]

The PWM for DRL's isn't doing anything too crazy, it's just turning the power to them on and off at about a 70% duty cycle.

 

[coolasice]

The PWM for DRL's isn't doing anything too crazy, it's just turning the power to them on and off at about a 70% duty cycle.

correct. it is merely being used to limit power to the bulbs.

 

[swede]

It's 80% according to GM shop manual, thanks for letting me back from my corner [emoji2]

 

[triz]

http://gmtnation.com/forums/topic/13524-saab-9-7x-fogs-as-drl-easily/#entry436760

 

[swede]

http://gmtnation.com/forums/topic/13524-saab-9-7x-fogs-as-drl-easily/#entry436760

Won't work different wire schematic between a 2002 TB and a newer 9-7X FYI

 

[Mooseman]

It's not because it's newer, the Saab 9-7X is different altogether. Same animal, different breed.