Resistor chip in key.


Old 10-22-06, 11:06 PM
Thread Starter
Join Date: Oct 2006
Posts: 24
Resistor chip in key.

My Pontiac SSE (95 supercharged model) has an ignition key with a small resistor embedded in the face of it. Either the key itself or the ignition switch is apparently wore out to the point that the car, while driving, will get a "security" light on the dash, a ding ding ding bell as if you just put the key in the switch, and will then shut off.
Wait for all the dinging to stop and the car will start up. The key LOOKS like it has a million miles on it. The embedded resistor is wore pretty bad.
As these keys can't be duplicated at Home Depot due to the resistor, and I understand they are very expensive at the dealer, it stands to reason that, if you know which wires in the switch sense the resistor, you should be able to clip the 2 wires (I assume 1 going IN the switch, 1 coming out) and hard wire a single resistor between them. The computer would then always read the correct resistance, never cutting out while driving due to the worn out key.

Now, I'm not trying to help any car theives out there but, does anyone have any thoughts or help on this? My Chilton's and Haynes manuals do not discuss key switch seurity wiring or the possibility that having a resistor hard wired in place could potentially run down the battery.
Sponsored Links
Old 10-22-06, 11:17 PM
Join Date: Dec 2001
Posts: 2,538
if you do a search on the internet im sure you can find more detail on bypassing the antitheft.
you basicly have the right idea just have to measure the resistance of your key and go to radio shack and buy a resistor that matches it, cut the two wires under the dash at the base of the steering column and solder in the resistor.
usually the wires get frayed and break or loose connection right near the tumbler and a new key and tumbler along with a new cut key from the dealer usually fixes the problem.
Old 10-22-06, 11:33 PM
Thread Starter
Join Date: Oct 2006
Posts: 24
Radio shack resistor was just what I had in mind. Reading the resistance across the key is no problem. Any chance it will run down a battery in time?
Old 10-22-06, 11:38 PM
Join Date: Dec 2001
Posts: 2,538
no it wont run down the battery.
Old 10-23-06, 07:47 AM
HotxxxxxxxOKC's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Jul 2006
Location: USA
Posts: 8,044

This is called a mechanical key. Each car has a Vats module (Brain) under the dash that communicates to the starter, fuel pump, and the ignition lock. Each vats module is randomly given a # (value) from the manufacturer. When the proper mechanical keys, with the proper vats chip (resistor value) turns the ignition lock, the vats module reads the chip on the key. If it is the correct chip, the vats module will tell the starter and the fuel pump to operate. If the wrong chip is read, the vats module will tell starter and the fuel pump to shut down.
Old 10-23-06, 09:05 AM
Banned. Rule And/Or Policy Violation
Join Date: Oct 2004
Posts: 120
VATS was the original and earliest forom of this system in which has the resistor in the key and not in the ign lock switch

passkey is the second and later system of this kind with the resistor chip key too,

passlock was the same system except the resistor is in the ign lock switch only and the key is just a regular key

you say the key is severely worn

well thats not a good thing

if i were you i would take the car and proof of ownership to the local dealer and have them cut a replacement factory key it is cheap 10 or 15 bucks and with that key on in the first position away from lock see if the security light is flashing or blinking, if so then leave the ignition onin that position until it stops blinking or flashing, then it should start right up and be no problem, if it does ever die just after firing up then it is being told to shut off the injectors because it thinks something isnt just right, it probably is worn igition switch in which is a commmon problem on these, with all the types of pass systems

i just had to go through this with a 98 olds achieva with passlock

it has a worn down copied key and i put a new ignition lock in it i reset the security light after removing the instrument cluster and cleaning the plug connectors for it because the security system controller chip is inside the back of the cluster, well its been pretty good since then so far but it has twice died after starting up for a second but then would start up and stay running right after that but that is alot better than how it was where it wouldnt start up and stay runnig for a day or longer sometimes,

i am going ot have the dealer cut a factory key for it and go from there, it still could be a bad instrument cluster in which is about 200 dollar rebuilt there isa company that does these i will hav to look them up and do it if the new key doesnt fix it, when i took my cluster out i saw a label stuck to the backside and dated 2002, so someone has been in i before and probably for the same reason and theres about 6 3-digit codes written on it too neat the date

security systems area real PITA i will never own a vehicle with it, are too much trouble and constantly malfunctioning

good luck
Old 10-23-06, 10:36 AM
Thread Starter
Join Date: Oct 2006
Posts: 24
for 10-15 bucks I'll try a new key cut from the dealer. Hopefully they go by numbers on the title as copying this one probably won't do much good. Hopefully it is JUST the key.
I have a new ECM on order and the old one is out of the car so it may be a few days before I can test it out...
Old 10-23-06, 01:09 PM
Thread Starter
Join Date: Oct 2006
Posts: 24
well, pontaic parts dept. said the key reads good in their reader. did it several times. said it MAY be the switch. 85 bucks for the switch, 35 for a key to fit it. since I have a new ECM on order, I figure I'll wait for that and see if it makes a difference before going the 120 dollars for a switch/key combo.
also, he said it was unusual for the car to cut off if it was the key. said a bad key/switch was primarilly an issue at start up only.
this one starts ok.
waiting on the ECM.
should be here by wednesday...

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Thread Tools
Search this Thread
Display Modes