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Key sensor in ignition switch

Tiny
RLSANCHEZV
  • MEMBER
  • 1999 HONDA CIVIC
  • 1.6L
  • 4 CYL
  • 2WD
  • MANUAL
  • 185,000 MILES
When starting, have to push and hold the key firmly into the ignition switch so that the key sensor will "recognize" the key and make the green key light stop blinking, allowing the car to start.

This condition happened after repairs to the ignition key switch that was locked out, the key would not turn, it was caused by wear in the mechanism of the internal pins.

Is the key sensor bad and needs replacement, do the keys need reprogramming, or both?

Thank you in advance for your expertise, have read your good explanations in your web-page.

My car is a 1999 Honda Civic 1.6 VTi with B16A2 twin cam engine, am located in Panama City, PANAMA.



Bobby Sanchez
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Saturday, December 28th, 2019 AT 8:55 PM

8 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,747 POSTS
Hi,

That's a tough one. The security control unit is behind the radio which has nothing to do with this. Next, there is a sensor in the key switch which sends a signal to the control unit to enable the engine to start. When you had the repairs done, was the tumbler replaced as well as a new key? Was there ever an issue like this prior to the repairs (before the tumbler broke)?

The idea that you have to push the key with force to get the light to turn off honestly sounds like a bad lock cylinder.

Let me know.

Joe
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Sunday, December 29th, 2019 AT 11:13 PM
Tiny
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Hello Joe!

Glad to receive your kind and expert reply, the work on the existing ignition switch was the replacement of the spring loaded pins in the tumbler which the key puts in the position that allows turning, like in all cylinder locks.

There was no issue with the green key light at all before the cylinder locked up as I was leaving the supermarket in mid '19; the car locksmith came and helped remove the lock in order to start the car, move the steering wheel and take it home, in the same neighborhood.

He then removed the cylinder, took it to his shop, proceeded to replace the worn pins, came back the next day and re-installed it, the car could be started again. The troubles with the key sensor started a few days later, the blinking light would not stop until removing the key, putting it back, pushing, holding then turning, etc, several times until the green light is off and the car can be started.

Have the two original keys that came with the vehicle.

Very best wishes, continue to have a nice Christmas season, and a Happy New Year.

Bobby
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Monday, December 30th, 2019 AT 11:11 AM
Tiny
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Hello again Joe, check the attached pictures of the ignition switch key sensor, the Honda part number is 39730-S04-G0.

Bobby
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Monday, December 30th, 2019 AT 4:18 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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Hi,

Did he reuse the old tumbler and just replace the pins?
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Monday, December 30th, 2019 AT 11:19 PM
Tiny
RLSANCHEZV
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Hello Joe,

Thank you again for your kind reply and sharing your technical expertise.

Yes, the locksmith reused old tumbler, replacing the worn pins.

Does changing the tumbler mean having to change all the locks in the car?

The key sensor coil or ring is what detects the key, correct? Why would a mechanical tumbler make the light stay blinking?

Best wishes

Bobby
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Tuesday, December 31st, 2019 AT 3:48 AM
Tiny
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Hi, Bobby.

No, there is no need to change all the locks. As far as the tumbler, what he did shouldn't have affected anything. However, something have gone back together differently. Have you spoken with the person that repaired it?

Take care,
Joe
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Tuesday, December 31st, 2019 AT 9:56 PM
Tiny
RLSANCHEZV
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Hello Joe,

Thank you again for your answers, talked to the locksmith again, he agrees that the mechanical repairs to the lock cylinder pins should not affect the electronic key sensor, he suggested cleaning the contacts. It's a small plastic plug, will try tomorrow to unplug, plug again which I have already done so.

If the sensor is replaced, do you know if this requires reprogramming the keys, computer, etc? -Am looking for the replacement Honda Part # 39730-S04-G0.

Best wishes,

Bobby
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Friday, January 3rd, 2020 AT 4:24 PM
Tiny
JACOBANDNICKOLAS
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Hi,

Try cleaning to see if that does anything. However, if you already have, it shouldn't be an issue. As far as replacement, to the best of my knowledge, it will need reprogrammed. You really don't need to get a Honda part, but in all honesty, I suggest it. Otherwise, you'll most likely end up with crazy issues.

Let me know if I can help in any way.

Take care and wishing you a good new year.

Joe
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Friday, January 3rd, 2020 AT 10:36 PM

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