Stock Wiring Harnesses

What will the stock headlight and fog light wiring harnesses handle?

The stock wiring harness is a little better than what some people give it credit for. This is what the stock harness can handle...

Note: This information is correct for a 1994 Model. I cannot guarantee that it is the same for all '93-'97 models, although it is very likely.

The Stock Headlight Wiring Harness
The headlights run off of 16 gauge wire. If you run a 30 amp relay in line with the lights, you can power, (also can be dependant on the relay), 2 - 130W MAX (with a 20% safety factor, which I would definitely use) Bulbs. Simply spoken, the 30 amp relay will provide all the power the 130W bulbs will need/use with 20% added in for safety, through the stock 16awg headlight wiring.

The Stock Fog Light Wiring Harness
The fog lights run off of 18 gauge wire. If you run a 30 amp relay in line with the lights, you can power (also can be dependant on the relay), 2 - 100W MAX (with a 20% safety factor, which I would definitely use) Bulbs. Simply spoken, the 30 amp relay will provide all the power the 100W bulbs will need/use with 20% added in for safety, through the stock 18awg fog light wiring.





Headlights in summary...
To run higher wattage bulbs in the headlights, and get all of the power they need supplied to them, run a 30 amp relay in line with the stock wiring (also with a direct power draw off the battery). The maximum wattage bulb you can safely run on the stock wiring is a 130W bulb.

Fog Lights in Summary...
To run higher wattage bulbs in the fog lights, and get all of the power they need supplied to them, run a 30 amp relay in line with the stock wiring (also with a direct power draw off the battery). The maximum wattage bulb you can safely run on the stock wiring is a 100W bulb.

How to calculate these figures
First use this formula to find the amperage output:
watts of device/volts of source = amps (current being drawn) or W / VDC = I

Example: 55w bulb/12volts (battery) = 4.6 amps
Most people say add 20% for safety...
4.6 + 20% = 5.5 amps

Then use this chart to determine the wire guage size needed. (From Reference Data For Radio Engineers)

Gauge of Wire-------Max Current (in amps)
20------------------------7.5
18------------------------10
16------------------------13
14------------------------17
12------------------------23
10------------------------33
8-------------------------46
6-------------------------60
4-------------------------80
2-------------------------100
1-------------------------125
0-------------------------150


Note: A larger gauge wire (smaller number) will flow a better current than the stock wiring. If it is a must for you to have a high steady current flow, then you might want to consider making a complete harness out of about 12 gauge wire, or you can buy heavy duty wiring harnesses. One such place to buy them is SUVLights.com



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