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Old 12-07-2017, 09:51 AM   #1
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Immobilizer/Electrical Problems

My 98 Base 986 has the M535 alarm flavor of immobilizer. Since buying the car in June the drivers door lock and the rear trunk light has not worked. The windows would also sometimes go down by themselves.

I have replaced the drivers door latch with one from eBay with no change to the lock. I have also put in a Viper paging alarm, mostly for the paging alarm function but also for key-less entry and trunk release.

The Viper remote control has always controlled the passenger door lock fine, the drivers door appears to lock then misleadingly unlock.

These were all livable problems until yesterday... I unlocked my car and pulled the rear trunk release and the trunk didn't open, at the same time the windows started dropping/raising repeatedly, the dome light and turn signal are on and wont turn off.

The car does start and drive.

So I drove it immediately home and unhooked the battery.

Obviously there is an issue with the immobilizer I've taken it out and it has a burnt smell. I'm waiting on a call back from ECU Doctors.

My big question involves my rear trunk, I assumed that it was cable driven when you pull the latch, but it doesn't open the trunk. Does anyone know how to open the rear trunk?

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Old 12-07-2017, 10:19 AM   #2
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Old 12-07-2017, 10:45 AM   #3
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Yep. That immobilizer is toast. Should cost you about $500 through ECU Doctors.
Your trunk is cable release, so probably a broken cable. You will need to locate the backup cable behind the rear bumper cover.
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Old 12-07-2017, 11:46 AM   #4
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I agree that the immobilizer box (Central locking unit) is toast. Additionally, one time my daughter was using one of my '99s and couldn't open the trunk. It was because the car was locked (with the driver's door open). After cycling the lock-unlock it opened fine. In that case, the trunk lever would not fully lift to the open position until the car was unlocked. In the case of a broken cable the trunk lever would move normally.
I am not an attorney, mechanic, or member of the clergy. Following any advice given in my posts is done at your own peril.
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Old 12-07-2017, 12:56 PM   #5
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Thanks guys... now off to find this cable in 30 degree weather.
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Old 09-30-2019, 10:53 AM   #6
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In a same subject, I ask for advice to similar issues...

Symptoms the year 2001 Boxter 986 'patient' has:
- key fobs do not lock/unlock while another do flash the led (both have new batteries)
- doors and alarm work well on turnign the key on the door lock (need ot be quick to place the key in to the dash key hole to avoid the alarm...)
- sometimes the front trunk does not open. Has to unlock/lock the central lock from dash few times OR start the car and press the recycle the central lock from dash button before the front trunk lock opens (non cable operated)
- sometimes the passenger door does not unlock when central lock is opened from the button at the dash

I'd really like to have the central locking system working and trunks as well as doors opening as designed. Also the having the key fobs to unlock/lock the car would be just fabulous.

Question is: Is there something that I can do or is the immobilizer / alarm /key fobs toast and in a need to be replaced or repaired?

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