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How to Determine the Ignition Resistance Value of 2004 Chevy Silverado Without the Key

GM and other manufacturers had a brainstorm during the late 1980s -- installing a resistor in a vehicles key to act as a second layer of security in addition to the physical lock cylinder. And it works well, when it does work -- and when you have the original key. But keys and cars dont always travel together and getting a matching key can be expensive. So youve got two options: you can bypass the whole system, or you can test the sensor to get its r-code and the right key.

Instructions

1

Remove the plastic shroud around the steering column in order to access the lock cylinder mechanism. The exact procedures for removing the plastic column covers will vary by truck, depending upon the options you specified. But look all around the shrouding, locate all the relevant screws and remove them. You should now see the ignition lock and the three wires -- orange/black, yellow and red/white -- connected to the Passlock II sensor.

2

Cut the orange/black starter wire and strip the ends so that you can reconnect it afterward. Do the same with the yellow Passlock II sensor wire. Crimp a male and female weather-tight quick-disconnect onto the ends of the wires so that you can quickly reconnect or disconnect them as needed.

3

Set your digital multimeter to read in ohms. Touch the negative (black) probe to a body ground, and the positive (red) probe to the key-side yellow Passlock wire. The resistor that your measuring is contained within the Passlock sensor itself, so thats what youll be measuring.

4

Turn your ignition key to the "start" position, and monitor the readout on your DMM. Record the reading in ohms. Repeat three to four more times, record each measurement and calculate the average. The PL2 sensor may not give the same reading every time, but the computer expects a bit of variance. You should see a reading of between 400 and 13,700 ohms; this is the resistance or "r-code" of your trucks ignition.

Posted by Unknown at 5:15 PM

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