Archive for the ‘Car’ Category

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GM Pass Key? I’ll pass.

December 30, 2007

It worked well for me for about ten years, but I finally got fed up with not being able to start my own car with my own key. I don’t like to get screwed on car repairs, so here’s what happened. I used Google for a while and found some websites with more information than I really needed, and I read it all. If you are having the same problem, you have probably figured out what is going on. You turn the key. The car doesn’t start, but the ‘SECURITY’ indicator blinks. You give up, and it stays lit. You know that the little resistor in the key is not making good contact.

You can go Google for those other sites as well, but you really don’t need all the information they give. I had been putting off the job because I thought I was going to have to crack open my steering column. This was not the case. Here’s how it worked on my 97 Camaro:

  1. Go to the electronics store and pick up a cheap multimeter. Open the box in the store and try to read your key with it. Quickly discover that this one is a total piece and you shouldn’t have wasted your money on it. Good thing you didn’t. Close the box and spend $50 on a real nice overkill version with auto-ranging. It’s still less than the $500 model.
  2. Leave the store and measure the resistance of the key in the peace and quiet of the hurting car. In my case it’s 886 Ohms. I’m no expert, but I bet GM picked values that don’t match up with widely available resistors.
  3. Well the store has 820. Will it work? I didn’t have the table I found online with the ranges about each of the 15 possible values in pass key. That’s OK. 1/(1/8200+1/1000) = 891. This is the resistance of an 8.2 kOhm and a 1 kOhm resistor in parallel. Don’t make this as hard as I did. Bring a calculator, or at least a pen. Buy the resistors and a 40W soldering iron.
  4. Here’s the action: twist the leads on the resistors together and solder them. Get down under the steering while and take all the screws out of the trim. Pull pretty hard on the trim to get it off.
  5. Literally the first thing you see is an orange wire coming out of the bottom of the steering column, housing two white wires. It’s plugged into another pair. One is black and white, and the other is purple and white. That pair is the car side. Cut it. Strip the ends and jury-rig twist the strands around the ends of the resistor.
  6. Try to start the car. It works. Try to start it again. It works again. Sweet. If it doesn’t work for you, go back to math and maybe buy more resistors. Better to get it close the first time.
  7. Solder each end of the newly-parallel resistors to one of those wires. Let the orange wire hang. Ensure a good solder job so there won’t be problems in the future. Wrap the whole thing in electrical tape and put the trim back on.
  8. Start the car again it works. Try again. It works again.

This is much better than having to try 6 times, waiting 4 minutes between each attempt, when I’m already late for work. I am thrilled to know that when I go to start my car tomorrow morning it will not be a 50/50 chance.