99 TL ignition key problem?
 

My 99 TL has had a problem in that when driving, the car would suddenly hesitate (cut off) for a fraction of a second and the Immobilizer System dash lite with the "key" icon would flash on, then the car would start up again and the lite would go off. Recently the car wouldn't start at all for a few minutes, then later it started. It runs OK when it is running, but I think there may be a problem with the ignition key code and/or the sensor in the ignition switch that reads the key. I switched to my spare ignition key and the problem re-occurred, so I don't think it is the key itself.
I checked error codes and besides the EGR errors that I have had for months, it now has a P1706, which is related to the transmission gear selector switch. I don't see that the P1706 code has anything to do with the car stopping and the "key" lite coming on the dash. Can anyone tell me anything about this problem??
Charlie

If I had to guess.....
 

It sounds like the immobilizer may be failing. Have heard similar stories from another brand that I follow, but have not heard of Honda/Acura problems in this area. This is one of those things that probably needs to go to the dealer to diagnose with their computer systems. OBD II most likely would not throw immobilizer failure codes.

I saw on one of the forums (maybe this one) that someone has made and sells an immobilizer circuit replacement chip that I guess bypasses the immobilizer for Acuras (at least newer ones) that have a problem with it. It sounds to me like Honda/Acura went overboard with electronic gadgetry here since this prevents you from starting the car with the wrong key, but if it fails, you are stuck even if you have the right key, and it may not be easy to fix (but is probably good for the dealer repair shop). Thanks for the info, I will see what I can do to verify the problem.

This is one of those things that probably needs to go to the dealer to diagnose with their computer systems. OBD II most likely would not throw immobilizer failure codes.




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Solution
 

I finally solved my problem. I removed the ignition switch electrical contact assembly from under the steering column – not too difficult using the instructions found below:

http://www.ehow.com/how_5292097_replace-ignition-switch-acura-tl.html

Then I disassembled the switch unit, cleaned off the contacts, and applied electrical switch lubricant to all the surfaces. I also bent down the contact “buttons” a little to compensate for wear of the contact surfaces, and stretched out the small pressure springs a little to provide more contact pressure. I then re-assembled the unit and installed it in my car, and I have had no problems since then; it’s been about a month so far. I don’t know if this would work if it had been more badly worn, but it did for me, and it didn’t cost anything but my time.
Also, the Immobilizer warning lite on the dash has not come on. I talked to a dealer service rep, and apparently that lite comes on anytime the power goes out at the ignition switch, so it was just a symptom of the switch not making good contact.
Hope this helps others with similar problems.