Note: Allpar does not take responsibility for the veracity of any information or opinions here, does not claim expertise, may not have verified or performed the fixes, repairs, or modifications, and is not responsible for any consequences. Please proceed at your own risk.
I recently installed the Webb Electric DRL-1 daytime running light module from Daniel Stern Lighting on Old Blue, my trusty 75 Plymouth Duster. In my opinion, this kit is the best way to run DRLs, as they work on the bright side of the front turn signal/park lights rather than the headlights, meaning the bulbs you are going to have to replace more often are cheaper, and there’s less chance of forgetting to turn on your headlights when it’s dark out, or forgetting to turn off the headlights when it’s not. [Editor’s note: they also do not cause unwanted glare for oncoming traffic.]
The DRL-1 lets you choose to have your DRLs in synchronized (both DRLs go out when turn signals are used) or unsynchronized (the opposite lamp remains lit when turn signals are used) mode. Changing from one to the other is as simple as cutting a wire.
As the kit came to me the contents are;
According to the instruction sheet, installation should take about an hour. It took me quite a bit longer than that, but a lot of that was in researching the wiring diagram in my Haynes manual so I could easily identify the circuits involved, making sure the car more or less matched the wiring diagrams, and doing it a bit different than the instructions say. I do believe I have a better installation than the instructions provide.
Daniel Stern’s website has a wealth of tech info, and should be read before undertaking any wiring or lighting project, this one included. The highest quality components aren’t going to work if installed in a halfway fashion, so before attempting a wiring project make sure you understand what you’re doing.
Along those lines, I spent quite a bit of time studying the car, a wiring diagram for the car, and the DRL to figure out where and how I was going to do the install. Colorado uses an oily and highly corrosive anti-icing agent on the roads in winter that manages to find its way into everything, and in spite of being a 34 year old classic the Duster is my daily driver, so it sees a bit of wintertime roads. With that fact in mind, and since all the wires I needed to work with were under the dash as well as under the hood, I decided to deviate from the plans in the kit and do the install under the dash.
For my install, or for any other with fender mounted turn signal indicators, the one possible undesirable operation is that the turn signal indicators light up with the DRLs. I didn’t figure this into my plans, but kind of like it that way, as it’s a good reminder in low light that you are running the DRLs and not by headlights. If light conditions are low enough for the indicators shining back at you get annoying, you probably need to turn on the headlights anyway.
The way around that is to splice into the turn signals after the junction for the fender mounted indicators, near the turn signals themselves. If your car is equipped with the Fuel Pacer system, you will have to splice into the turn signal wire after the indicator to keep from interfering with that system. If doing an under-hood installation, look for a suitable place where the unit won’t get damaged and can be mounted with the wiring coming out the bottom of the module. One possibility is on the rear of the core support beside the radiator.
To install the system you will need to cut the wires for the turn signals, and tap into the wire for the parking lights. The system also shows tapping into the ground wire for the parking lights, but a separate ground will work as well. Additionally you will have to tap into a fused ignition circuit capable of at least 15 amps.
The only fused ignition feed on 74-76 A bodies is the G5 circuit that feeds from fuse 6, but it is only 3 amps to feed the gauges, so count that out. You will have to install an inline fuse from a source off the run side of the ignition switch, or do as I did and make the unused number 5 position in the fuse box into a fused ignition feed. [Guide to using the fused ignition feed]
On the 1974-76 A bodies, the color codes for some of the lighting wires change at the bulkhead connector, so below are the codes both under the dash and under the hood.
Left turn signal
D6 18 gauge
black/light green tracer
Right turn signal
D5 18 gauge
L6 18 gauge
L9 18 gauge
Under hood ground
J2 14 gauge
The wiring colors for the DRL-1 module are as follows
Left turn to switch
Left turn to light
Right turn to switch
Right turn to light
Synchronizing wire loop
Before cutting wires you will want to make certain you are cutting the right wires, it’s much easier to get it right the first time instead of repairing a mistake later, or worse, letting the magic smoke out of your electronics. Before disconnecting the battery, I used a voltmeter to verify that the wiring diagram was correct on the wiring colors for the various circuits.
After circuit verification, the very next thing you will want to do is DISCONNECT THE BATTERY! If doing the under dash install you will need to gain access to the wiring, I used the run where the main harness goes from the dash to the bulkhead connector by the brake pedal mount. The harness runs through a split tube that is easily removed, then remove the tape covering the harness.
I prefer to work one circuit at a time, which means I locate, cut and/or strip, solder, and re-insulate one circuit at a time. This helps avoid a lot of confusion and makes certain that everything comes out as planned. Another trick is to keep the instruction sheet and a notebook handy when working an electrical project. I don’t trust anything to memory; reference the notes and instructions often to avoid mistakes.
I started with the left turn signal wires, then went on to right turn signals, park light wires, and ignition and last the ground.
Using the notes I made about the circuit colors, the wire was cut and soldered to the wires from the module. There is a difference in which left turn and right turn wires go to the switch and to the light, make certain you get them right. After soldering I used heat shrink tubing over the joint, if using heat shrink tubing remember to slide it on before connecting the wires. If inclined to do a faster job, the wire nuts from the kit can be used on the turn signal connections.
The parking light wire doesn’t need to be cut, only tapped into. Heat shrink tubing doesn’t work here as I don’t cut the wire for this; only strip enough insulation for the connection, so there is no way to install the shrink tubing. Instead, after soldering I tape it securely with electrical tape. If using an inline fuse connector from the ignition circuit, or the under hood connection for the ground if using the light ground as the instructions say, this will be the same.
If inclined to do a faster job, the quick connectors in the kit will work here. I used a ring terminal for the ground, secured to the bottom of the dash where the factory steering column ground is. A different article (coming soon) explains how I used fuse 5 in the fuse box for an ignition power supply.
After all your connections are made, secure all your wires out of harm’s way and mount the unit securely, making sure the end with the wires coming out of it is pointing downward. If using my under dash mounting, you need to tape the main wiring back together and reinstall the split tube before doing this.
The DOT regulations for commercial vehicles call for wiring to be secured in a workman like fashion. I live by these rules for wiring. If you take precautions to keep your wiring is out of harm’s way it lessens the chance for damage.
Now for the moment of truth, reconnect the battery and test the system. If all goes well, everything will work as it ought to, fuses won’t blow and smoke won’t start rolling.
The white wire on the module is to program the module for synchronized or unsynchronized mode. I left it connected until after I saw how it operated, but ultimately clipped it as unsynchronized mode is how every other vehicle I’ve ever seen with turn signal DRLs operates. Below are the pictures with and without DRLs.
One future upgrade I might make is the installation of a relay to make the DRLs operate only when the car is moving, as right now they are on any time the ignition switch is in the run position. This is one reason you want to pull the power from them off the ignition circuit and not the accessory circuit, you don’t want the DRLs running down the battery every time you’re sitting somewhere just listening to the radio. The upgrade shouldn’t be too hard to do; it involves feeding the DRL module off the 87a terminal of a relay, and supplying the relay ground from the park safety switch or parking brake switch. When I get the materials, I’ll update the article with material list and wiring diagram.
Why install daytime running lights? In some places it’s the law that if you don’t have them you have to run with your headlights on. I’ve read a lot of safety studies that show that they help, but I took a lot of them with a grain of salt. Too many times people presenting data that shows a drastic change have manipulated their data, and about the 50th time you see this it tends to make one skeptical of all data.
Most of the newer big rigs I’ve run had them, usually the same way on the turn signals, although one of them had them on the headlights. I pulled the DRL relay on that one because changing headlight bulbs every 2 or 3 months gets expensive after a while, and it stopped the problem of discovering that I’d been running in the dark without the taillights on. After seeing the difference personally on a car I know, I’m convinced the DRL-1 kit was a good modification to make, as it certainly improves visibility without the downside of shortening the life of the most expensive bulbs on the vehicle.
[Editor’s note: when headlight DRLs are used, reputable studies show that having them at partial power is around as effective as full power, without causing glare for oncoming traffic, burned-out bulbs, excessive fuel use, etc. This would lengthen bulb life and reduce power demands, but it raises the cost slightly. Some automakers have switched from using headlights to parking lights, to reduce electrical load and avoid driver confusion over whether the headlights are on. The ideal seems to be specially designed daytime running lights, mandated in Europe but not in the United States.]
Daniel Stern Lighting
Disclaimer: The information provided in this and linked pages are accurate, to the best of our knowledge, but we are not necessarily experts or authorities on the subject matter. Neither the author nor Allpar.com / Allpar, LLC is to be held responsible for the use of the information or implied advice by the reader or anyother party. This page is offered “AS IS” and without warranties of any kind. If you use this page, you release the author and Allpar, LLC from any liability whatsoever.
All Mopar Car and Truck News