DRL Wiring Question

[SWC]

Adding driving lights to Canadian trucks makes wiring interesting! I have spliced into the high beam wire to run additional driving lights. To my frustration I have found that the DRLM (Daytime Running Light Module) uses the high beam at reduced volts. The voltage is high enough to pull in the relay and power the driving lights. I have unintentionally had the driving lights on in the daytime with my headlights off. I have been informed by truckers most unceremoniously of my error! The only other way that I can think of is to use the high beam indicator light on the instrument panel. The interesting thing here is that there are 12 volts to the indicator light when the high beams are off (DRL and low beam), and 0 volts on high beam. This power comes from the DRLM. I can use a relay with the 87 or 87a output and use the side when power to the relay is off. Or is there an easier way?

I also want to run heavier wires to the Dodge headlamps. How can I wire this and still use the DRL?

Any solutions are welcome.

Thanks.

Stan

 

[Tardog]

DRL's

I can help as I have been through this before installing sport headlights. You are right that there is a small voltage at the highbeam beam and at the indicator light, not good for running a relay. So here is what I discovered, At the DRL module there is a trigger wire that runs the Highbeams. On my 97 it is an 18 gauge red/grey tracer wire. I tapped into this wire to run my relays and it works perfect . Hope this helps

 

[jcbrown]

Driving Light's Relay...

You need to wire the driving light's relay for switching ground. Driving Light's are wired hot, relay ground's the circuit.



Relay ground wire is dimmer switch high beam output, red/orange tracer, pin 6 of Daytime Running Lamp Module. Reference pages 8W-50-8 and 8W-50-12 of Service Manual. Low beam this wire is positive, high beam this wire is ground.

 

[Tardog]

Good catch Mr. Brown, I forgot that they changed the trucks to a switiched ground for the light circuit on the newer rigs. I sit corrected.

 

[jcbrown]

Learning Curve...

Originally posted by Tardog

Good catch Mr. Brown, I forgot that they changed the trucks to a switiched ground for the light circuit on the newer rigs. I sit corrected.

There was a learning curve when I purchased my truck new. I like switching ground. Less stress and current (amp) on relay's.



Was another learning curve when installing switching power fog lamp relay from previous vehicle to the truck using switching ground.

 

[SWC]

jcbrown, I currently have the driving lights wired as you have described using the red/orange wire to gound the relay. The only other way is to use the red/grey wire from the DRLM to the high beam indicator driver.

Thanks for ideas so far.

Stan

 

[jcbrown]

Originally posted by SWC

Adding driving lights to Canadian trucks...

Do you have Quad Headlamp's?