The PLUM-4 polyvalent logic module adds fully automatic daytime running light (DRL) functionality to a vehicle's front turn signal lamps by operating them steadily when the engine is running, the parking brake is released, and the parking/tail lamps or headlamps are switched off. The turn signals still work normally; when the DRLs are on, signalling for a left turn (for example) will flash the left turn signal while the right one remains steady-lit, still providing the DRL function. Activating the hazard flashers (4-way flashers) overrides the DRL function; the turn signals on both sides of the vehicle will flash—all just like a factory installation.

This DRL implementation complies with US and Canadian DRL requirements, and has major advantages over headlamp-based DRLs. Because directional signals are legally required to shine light in a wide range of horizontal and vertical angles, the DRLs are likewise visible from a wide range of viewing angles for maximum conspicuity and safety benefit in avoiding angular collisions with pedestrians, bicyclists and other motorists. Turn signal bulbs cost much less, consume much less power and have a much longer lifespan than headlight bulbs. There is no undue glare with turn signal DRLs, as can be a problem with headlamp-based DRLs. And, it's much harder to forget to turn on your full lights at night, because the DRL color is amber rather than white so you don't see misleading reflections of your "headlamps" (actually your DRLs) in shiny surfaces after dark.

The PLUM-4 is all-new, and vastly improved over the previous-type module. Every single component is significantly upgraded, it's now fully potted (weatherproof), it has four output channels instead of two and higher current capacity, and it is easier to mount. The module is built in the USA to my specifications.

Unlike the previous module, this new one is a 4-channel device able to add daytime running light functionality to the front turn signals and add turn signal flashing to the front sidemarker lights; previously you would have needed two modules, one for each newly-added function. Of course, if you only want to do one of these things, the new module will handle that just fine, too.

This compact, dependable module, when installed properly, will give years of trouble-free service. It comes with all the necessary connectors and can be installed under the hood, under the dash, or near the right or left front turn signal on a vehicle of just about any description. It is designed and intended to add an effective crash-preventive function to vehicles equipped with legitimate lamps and bulbs; it is not for use with "switchback LED bulbs" and other such unsafe playtoys.

Here are three short movies of added-on turn signal DRLs in action:

Here is how the module gets connected into the car's wiring. This diagram shows all the hookups to add the DRL function to the front turn signals and add turn signal flashing to the front side marker lights; if you only wish to add the DRL function, you may disregard the side marker lights, their wiring, and the module's white and green wires. Click this diagram for a larger version in a new browser tab

To add the DRL function, you will be making four connections to existing wires on one side of the car, and only two on the other side (plus one more connection to an ignition-switched source of power).

The module's yellow and brown wires will connect to the cut ends of the front turn signal feed wire on one side of the vehicle, and the module's pink and violet wires will connect to the cut ends of the front turn signal feed wire on the other side of the vehicle.

Most installers choose to mount the module on one side of the car, tucked out of harm's way (e.g. inside the front bumper cover, behind the lamp housing, or in one front corner of the engine bay), then extend the correct two module wires over to the other side of the vehicle. Some installers choose instead to access the applicable wires inside the passenger compartment, under the dash at the base of the steering column.

In addition to the connections at the turn signals, you will need to locate a wire that is live with +12v when (and only when) the ignition is switched on. Many cars have a fusebox in the engine compartment, and you can often find an appropriate circuit there. If necessary, you can run a wire into the interior of the car. Select a circuit that's fused for at least 15 amps. This is what the module's dark blue wire is for, and it comes with fusebox tap-in adapters for easy, safe hookup.

Installation

Installation should take 20 to 60 minutes. You will need a wire cutter/strippers and a pair of pliers to make the connections. You will be using wire taps. The supplied ones are an excellent type called Posi-Taps. Don't substitute the fold-over-and-crunch "Scotchlok" type taps—really, please don't; you'll regret it later. If you need more Posi-Taps, you can get them directly from the maker.

These instructions assume that you will be installing the module near the left front turn signal. If there is more room on the right side of the vehicle or you prefer a mounting location on the right, simply read "left" for "right" and vice-versa in these instructions.

Mount the module out of harm's way. It is highly weatherproof and splashproof, but please don't make it go swimming underwater for prolonged periods, and don't mount it where the tires will constantly fling pebbles, ice, and slush at it. You may lengthen any of the wires in order to place the module in an optimal location. Use № 16 primary wire. It is best to extend wires using wire of the same colour. If you can't, make sure to mark your wires clearly so you will be able to make the proper connections.

1. Locate the wires for the left front turn signal. If you have a wiring diagram for the car, this will help you identify these wires. If not, then you may need to use a voltmeter or test light to identify the correct wires. Many vehicles have combination park/turn signals with two-filament bulbs. The dim filament is used for the parking lamp function, and the bright filament is used for the turn signal function. These have three wires: one feeding the dim filament (parking light), one feeding the bright filament (turn signal), and one ground.
   
   
2. Connect the module's black wire from the module to a good ground. This can be the vehicle's front turn signal ground wire, or any convenient good ground.
   
   
3. Connect the module's light blue wire to the vehicle's left parking lamp feed wire. This is a tap-in connection; the parking lamp feed wire remains uncut&mash;the module wire forms a tee junction with the vehicle's wire.
   
   
4. Cut the vehicle's left front turn signal feed wire, and strip 13&nbdp;mm (½") of insulation from each end. If your car has side turn signal repeaters on the fenders or sideview mirrors, and/or front sidemarker lights that flash with the turn signals, you want to exclude these from DRL operation—you want only the front turn signals to burn full time as DRLs—so make sure to cut the turn signal feed wire as close to the front turn signal as necessary to be "ahead" of where the sidemarkers and/or repeaters tie into the turn signal feed wire.
   
   
5. Connect the module's pink wire to the cut end of the vehicle's left front turn signal feed wire that leads to the vehicle's wiring harness. Connect the module's violet wire to the cut end of the vehicle's left front turn signal feed wire that leads to the left front turn signal lamp.
   
   

1. Locate the wire that feeds the vehicle's right front turn signal.
2. Cut the vehicle's right front turn signal feed wire, and strip 13 mm (½") of insulation from each end.
   
   
3. Connect the module's yellow wire to the cut end of the vehicle's right front turn signal feed wire that leads to the car wiring harness. Connect the brown wire to the cut end of the vehicle's right front turn signal feed wire that leads to the right front turn signal lamp.
   
   

The module's dark blue wire gets connected to a switched power circuit&mdashone that is live with +12v only when the ignition is switched on. Use a circuit that is fused for at least 15 amps. Select the appropriate fusebox connector to make this connection or, if you have a type of fuse not catered for in the connector selection or wish to tap in elsewhere, use a suitable connector or wire-joining technique.

Tying Into the Parking Brake

This is optional. For factory-type operation of the DRLs, add a Normally Closed (or Changeover) relay in the module's ground (black) wire. Such a relay can be furnished at the time of ordering the module. Hook it up this way:

• Relay terminal 85: tapped (tee-connection) into vehicle's parking brake warning light wire
• Relay terminal 86: To ignition-switched +12v (same as module's dark blue power wire