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Re: 1998 Ford Ranger Air Bag Code 27
Thanks to this forum for fixing the code 27 on my Ranger. I tried the Radio Shack red LED 276-209 but found it extremely dim and difficult to tell if it was on.
Some quick web searching yielded the basic current and voltage limiting circuits for LEDs so using those calculations as a guide I used the yellow LED (276-0351, $2.79 for 2) in series with a 470 ohm 1/2 watt resistor (271-1115, $0.99 for 5). The yellow LED was rated 1900 mcd in light output versus 33 mcd for the red LED 276-209. It is every bit as bright as the original lamp and no problems after several hundred miles of driving. The resistor will keep the LED supply voltage and forward current well below its 3.0 V 30 mA maximums and closer to its 2.1 V 20 mA typical values. It is drawing enough current to keep the airbag diagnostic module happy.
As in the post above the LED is directional. It is a diode so if wired in backwards it won't pass current and will appear to be an open circuit. In my case as in the earlier post the negative side (short lead on the LED) was toward the short side of the rectangular board. I am not sure it is critical which side of the LED the resistor is wired into. I wired mine on the positive side of the LED. If following the lamp circuits from the connector on my truck the negative side of the lamp circuit was a yellow wire with a green stripe and the positive side a black wire with green stripe at the connector.
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