Hardwiring Daytime Running Lights for 98.5-02 Trucks

[kgeiger81]

Wiring the headlights to stay on at all times is straightforward. Below is a list of materials and tools needed.

Materials List:
Accessory relay with normally closed and normally open terminals
16ga Primary wire in black, white and red
T-tap wiretaps
Assorted crimp terminals (preferably the insulated type)
Electrical tape
Fuse holder with 5 amp fuse
Toggle switch (optional)
Split loom

Tools:
Circuit tester
Wire strippers
Crimp tool
Utility knife
Cable ties
Basic hand tools
Electrical tape

Wires at headlight:
Black – Ground
Violet w/ White tracer – Low
Red w/ Orange tracer – High

Basic accessory relay


T-Taps


Chrysler uses a negative switching circuit that controls the headlights. If you take a circuit tester and check each of the wires on the headlamp harness, you will find that all three wires are hot all of the time. If you ground out one of the wires, either the high or low beams will turn on.



The first step is to decide if you want switch installed in the dash somewhere to be able to turn off the lights. If you do want a switch, choose a place where you would like to mount the switch. I used a switch that had an LED in it when the switch was on to let me know that the DRL’s were on. You need a power source that is on when the ignition is on. An easy way is to tap into one of the ignition wires in the ignition switch harness which is behind the knee bolster under the steering wheel. Use a circuit tester to verify that the wires are only on when the ignition is on There are two choices, a solid blue wire or a black w/ white tracer. Best choice would be the smaller wire, although I do not remember which one it is. Use a T-Tap to make a connection (unless you are good at soldering) for the power source to the relay. One of the wires is 14ga I believe and a blue tap will work. (Simply close the tap over the wire and squeeze the large end closed with a needle nosed pliers). If it is bigger, you will need a yellow T-Tap. If you use a switch, this will go to the switch. You must put the fuse holder on this wire between the ignition source and the switch or relay whichever you decide to use. Then put another wire from the switch down to the coil of the relay on terminal 85. Use red wire for this. If you decide to use a lighted switch, most of them need a ground wire for the LED to light up.

Next, you need a good clean ground. This will serve two purposes, one for providing a ground for the relay and the other for turning on the lights. You should be able to find a ground bolt behind the knee bolster under the steering wheel and make use of it. You will need a ground wire on terminals 86 and 30. 86 is the other wire for the coil and 30 is the common wire, which will be used to turn on the lights. Use black wire for the ground.

Now you need to run a white wire through the firewall to the front of the truck behind the left front headlight. Use a T-Tap to splice into the Violet w/ white tracer wire. I believe the headlamps have 18 or 20 ga wire so you will need a red T-Tap. This is the wire for the low beams. Attach the other end of this wire to terminal 87 on the relay. Make sure when you are running the wire through the firewall that it does not chafe anything. It’s best to use a split loom to run the wire in to protect it. Secure all of the wires with cable ties and your all set. The relay should be installed behind the knee bolster under the steering wheel. To secure it you could just cable tie it to another wire loom under the dash.

When you turn on the key, the lights should come on at full intensity. Or if you decide to use a switch (which I strongly recommend) they will come on with the switch. When you turn the headlights on manually, you’ll notice that the lights are a little brighter than before. Just remember to turn off the switch when you turn on the brights. You will burn up the headlamps if you have the low and high beams on at the same time.

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- Kevin -
'07 2500 5.9L, K&N intake, Magnaflow exhaust, Cat and silencer ring MIA,
Autometer Phantom II's, Bully Dog Triple Dog, B&W Turnover Ball
My old truck: 1999 Dodge 2500 CTD, ACDC

[BBRam]

Awesome writeup, Thank you!

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03-3500, DRW, QC, 4x4, R850 BD Twins, BD IC Boots, BD Billet Flexplate, DTT Trans, Lockup Switch, SMARTY TNT-R / TS MP-8, Wicked Diesels Eliminator Fuel System & Coolant Bypass, Floor It Stage 3 CP3 & Rail Cap, BIG Stix's by FTE, ARP Head Stud's, Springs, Fluidampr, ATS ARC-FLOW, Mag-Hytec, AFE, Boost, Drive Pressure, Pyro, Fuel Pressure, Tran's Temp, Rail Pressure Gauge, GDP Ladder Bars, GrandRock 7" Miters. (R/T .021, 60' 1.76, 1/4 ET 13.03 @ 102.05 mph)

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