Since the Canadian JK uses the highbeam circuit all the time, albeit modulated, I'm not sure he can use that as a trigger source. I would think the modulated signal would be enough to close the relay. (Or even worse buzz the relay.) As a result the driving lights would always be on even if the (full brightness) high beams aren't activated.
Now I read that the DRLs on the JK can be set to modulate either the high or the low beam circuit depending on the country that it is localized to. Do we know for sure the Canadian version uses the high beams?
You are absolutely correct -I incorrectly assumed they were modulating the low beam for driving lights. So to use the high beam driver wire would have to run the experiment. My JK doesn't have DRL - depends on the pulse widths and what is the minimum voltage (or in this case pulse) it takes to hold the relay. The relay I mentioned requires only 7.8V to trip so the DRL might trip it.
I should check how this is being done in California - the law requires driving lights be wired to high beams and I see plenty of DRL vehicles.
Could build a RC filter to limit the PWM to the relay during DRL pulsing (or a semiconductor comparator circuit to trigger at higher voltage) but that may be a bit tricky to figure out.
Perhaps this would work to eliminate the pulse problem, have PWM trigger this which in turn triggers a relay coil with 12V, would have to add a few components to block the lower DRL or just run it off the high beam switch on the dash:
The 2007 JK service manual says:
"Daytime Running Lamps - Daytime Running Lamps (DRL) are standard equipment on vehicles manufactured for sale in Canada and optional on vehicles manufactured for the United States. Vehicles with DRL illuminate the high beam filament of each headlamp bulb at a reduced intensity to serve as the DRLs."
"DAYTIME RUNNING LAMPS
Vehicles equipped with the Daytime Running Lamps (DRL) feature illuminate the high beam filament of both headlamp bulbs at a reduced intensity when the engine is running, the parking brake is released, the headlamps are turned OFF, and the optional automatic transmission gear selector lever is in any position except PARK. The park lamps may be ON or OFF for DRL to operate. For vehicles with a manual transmission, the DRL will operate in any transmission gear selector lever position. The TIPM must be programmed appropriately for this feature to be enabled.
Once enabled, anytime the TIPM receives electronic messages over the CAN data bus from the Powertrain Control Module (PCM) indicating the engine is running, from the ElectroMechanical Instrument Cluster (EMIC) (also known as the Cab Compartment Node/CCN) indicating the status of the left (lighting) multi-function switch is in any position except headlamps ON and the parking brake lever is released, and from the Transmission Control Module (TCM) indicating the automatic transmission gear selector lever is in any position except PARK, the TIPM provides a pulse width modulated voltage output to the headlamp high beam bulb filaments through high side drivers on the right and left high beam feed circuits to produce illumination at a reduced intensity."
The headlamp system includes the SCM, the EMIC, the TIPM, and the left (lighting) multi-function switch on the steering column. The headlamp bulbs have a path to ground at all times through their connection to the engine compartment wire harness. The engine compartment harness has takeouts with eyelet terminals that are secured by nuts to ground studs on the front end sheet metal within the engine compartment. The TIPM will store a Diagnostic Trouble Code (DTC) for any shorts or opens in the headlamp circuits.
The SCM monitors a hard wired multiplex input to determine the status of the left multi-function switch and whether the headlamp high or low beams are selected. The SCM then sends the appropriate electronic headlamp switch and headlamp beam select switch status messages to the EMIC over the LIN data bus. The EMIC then sends the appropriate electronic headlamp and headlamp beam request messages to the TIPM over the CAN data bus. The TIPM responds to these messages by providing a pulse width modulated voltage output to the headlamps through high side drivers on the right and left low and high beam feed circuits to illuminate the selected headlamp filaments. The TIPM also sends the appropriate electronic messages to the EMIC to control the illumination of the high beam indicator. When the optical horn feature is selected, the low beams will shut OFF about 200 milliseconds after the high beams are activated.
The TIPM also remembers which beams (LOW or HIGH) were selected when the headlamps were last turned OFF, and energizes those beams again the next time the headlamps are turned ON. The TIPM provides a battery saver (load shedding) feature for the headlamps, which will turn these lamps OFF if they are left ON for more than about eight minutes with the ignition switch in the LOCK position. The SCM and the EMIC each provide a fail-safe feature for the headlamps, which will cause the TIPM to turn the low beam headlamps ON automatically if there is no input available from the left multi-function switch. The TIPM also provides a fail-safe feature for the headlamps that will turn the headlamps ON automatically whenever a loss of CAN bus communication is detected with the ignition switch in the ON position.
Each headlamp includes an integral adjustment screw (domestic markets) or screws (export markets) to be used for static aiming of the headlamps."