For 1990-2009 cars

### Security System Indicates Tamper

### Circuit Description

The passlock sensor data is supplied to the body control module (BCM) by circuit 1836.

The passlock sensor data supplied to the BCM is in the form of V-codes or voltage codes. When the proper ignition key is turned in the ignition switch, the correct V-code is supplied to the BCM. The BCM responds by sending a serial data password to the engine controller allowing the engine to run.

The security resistor is bypassed under a tamper condition (possible external magnet applied to sensor). In this mode, a specific V-code is supplied to the BCM. The vehicle will not start in this mode.

### Conditions for Setting the DTC

• | Ignition is in RUN, CRANK

• | The passlock data equals stored tamper V-code for 1 second

• | Turns on service wrench telltale and security telltale

### Diagnostic Aids

• | Check for poor connection at the BCM. Inspect harness connectors for backed out terminals, improper terminal mating, broken connector locks, improperly formed or damaged terminals and poor terminal-to-wire connection (terminal crimped over wire insulation and not conductors).

• | Inspect the wiring harness for damage. Check for broken or chafed insulation.

• | Check for poor connection at the passlock sensor.

• | If fault is suspected to be intermittent, wiggling harness wiring may help in locating fault.