Originally Posted by ltooley
I have been told that you can cut certain wires on the ignition to deactivate passlock. Also have found in my search that when you add a remote start to this car that you have to buy a GM passlock bypass interface to add to wiring, will this work without the remote start system installed? If I add a remote start system will this correct my problem?
Adding a remote start system with a bypass interface or relays and resistors isn't your best option if your Passlock problem lies in intermittent problems due to bad passlock wiring connections in the terminals. Yes, you can just cut the Yellow Passlock Data Wire while the engine is running to Disable the Passlock. There is no need to add a remote starter. The best way to disable the Passlock is by adding a toggle switch into the Yellow Data Wire as described in this GM engineering report.
Here is the procedure to follow for cars:
PASSLOCK I or II DISABLEMENT
The following is a procedure to disable Passlock I or II Systems for vehicles in which remote start/stop system installations are required. This procedure is required because a remote start system will not function with the current Theft Deterrent System (Passlock) which is included on many 1996 and up GM vehicles.
Please note that this modification is intended to be used only in conjunction with the installation of a remote start/stop system and does not provide a procedure to install a remote start/stop system.
If an attempt is made to start a vehicle by a means other than a key rotation in the ignition switch, the Body Control Module (BCM) will interpret this start as a vehicle theft and disable the fuel injectors.
A minor wiring modification may be made to allow the vehicle to be started remotely. This modification includes adding a switch to allow the customer to select “ON” to disable Passlock or “OFF” for normal Passlock operation.
CAUTION: When this modification is performed and the switch is set to the ON position, the theft deterrent feature will be disabled. When the theft
deterrent is disabled the SECURITY or THEFT telltale will light up indicating that the theft deterrent system is NOT functioning.
Refer to appropriate GM service manuals and/or SVMQP Electrical Guideline Manual for instruction on splicing and electrical connections.
1. Select a suitable on-off switch (see note below) which will be used to disable/
enable the Passlock System. Mount the switch in a location such that it is
accessible to the driver and will not interfere with normal vehicle operation.
NOTE: This is an extremely low current circuit (approx. 7mA), it is therefore very important that a high quality, low energy, fast acting switch be utilized
for this application.
2. Turn the ignition switch to the OFF position.
3. Locate the Main Ignition Switch Harness in the Column. GM's Passlock System wires exit the Ignition Switch Tumbler together and then join with the Main Ignition Switch Harness. (See http://www.bulldogsecurity.com/
and select your Make, Model and Year for wire colors and clues on the quickest way to access these wires.)
4. Locate the Yellow Passlock Data Wire which is included in a bundle of three tiny (20 GA) wires wrapped in friction tape.
Cut this wire and splice a 0.5mm2 (20 GA) yellow wire to each end of the cut wire.
Keep wire length to a minimum. Route modification wires clear of moving parts.
Connect the yellow wires to the switch such that the contacts are OPEN when the switch is in the ON position.
5. Turn modification switch to the OFF postion (contacts closed).
6. Start vehicle to verify normal operation. If engine “cranks but will not start"
recheck the switch position (contacts should be closed), wire connectors and
To enable remote start:
Start the engine with the ignition key (modification switch must be in the OFF
position). Turn modification switch to the ON position (contacts open). The
SECURITY or THEFT telltale will light up indicating that the Passlock System is inoperative.
Once the SECURITY or THEFT telltale has been on for at least 5 seconds the vehicle can be turned off and then remotely started.
To disable remote start:
The Passlock System can be reactivated by turning the modification switch OFF
Vehicle can either be running or off when this is done.
Please note that the VCM/PCM will record Diagnostic Trouble Codes (DTCs) related to the security system when the modification switch is in the ON position (circuit open). This is due to the way that the VCM/PCM interprets this condition.
Any condition which removes battery power from the Vehicle Control Module/Powertrain Control Module (VCM/PCM) (e.g. dead battery, disconnected harness connectors, etc.) will prevent the vehicle from being restarted. If the engine exhibits a “cranks but will not start” symptom, place the modification switch in the OFF (contacts closed) position. This will reactivate the Passlock System and allow the vehicle to be started with the ignition key.