Circuit Description
The Anti-Theft device, called Passlock system utilizes three components to determine if the vehicle has passed theft, the lock cylinder, ignition switch, the electronic instrument panel cluster (IPC), and the PCM. After the vehicle has passed theft, the PCM will continue normal engine operation. When the Passlock system does not allow theft passed, the PCM disables the fuel injectors and DTC 1629 is set. Additional information can be found in Section 9D Theft Deterrent System.
When starting the engine, the PCM looks for a password from the instrument panel cluster (IPC) through the serial data line (CKT 800). If the Password is not recognized or not present, the PCM will not operate the fuel injector and the engine will stall before 4 seconds. There are two modes of tamper detection and the modes are as follows:
| • | Short Tamper Mode - Engine may start and stall quickly. THEFT SYSTEM telltale will flash on the IPC for 4 seconds |
| • | Long Tamper Mode (More than three starting attempts or an invalid password is received) - The Engine will crank but will not run for at least 10 minutes and the THEFT SYSTEM telltale will flash on the IPC for the 10 minutes. |
Conditions for Setting the DTC
| • | An unrecognized or no password is sent to the PCM from the IPC. |
| OR |
| • | A bad timing cycle sent from the IPC to the PCM. |
Action Taken when the DTC Sets
| • | MIL does not illuminate. |
| • | The engine will stall. |
Conditions for Clearing the DTC
| • | A history DTC will clear after 40 consecutive ignition cycles have occurred without a fault. |
| • | DTC(s) can be cleared by using a scan tool. |
Diagnostic Aids
An intermittent may be caused by a poor connection, rubbed through wire insulation, or a wire that is broken inside the insulation.
Any circuitry that is suspected as causing the intermittent complaint, should be thoroughly check for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wiring connections or physical damage to the wiring harness.
Test Description
The number(s) below refer to the step number(s) on the diagnostic table.
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In order for the PCM to communicate to the IPC, it must do it through a serial data line. Using the scan tool verifies the connection between the scan tool and the IPC. This test verifies that the IPC is communicating.
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If DTC 21 on the IPC is set, it means that the IPC cannot communicate with the PCM.
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This step checks to see if the problem is in the PCM.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||
1 | Was the On-Board Diagnostic (OBD) System Check perform? | -- | Go to Step 2 | |
2 |
Does engine start and continue to run? | -- | Go to Diagnostic Aids | Go to Step 3 |
Can scan tool communicate with IPC? | -- | Go to Step 4 | Go to Step 9 | |
Read IPC DTCs from scan tool. Is DTC 21 (PCM communication loss from IPC) stored? | -- | Go to Step 5 | Go to Step 11 | |
5 | Are any other IPC DTCs also stored? | -- | Go to Section 9D | Go to Step 6 |
6 |
Is resistance less than specified value? | 0.5 ohms | Go to Step 7 | Go to Step 8 |
7 | Check PCM connection and make sure it is clean and tight. If OK, replace PCM. Is action complete? | -- | -- | |
8 | Repair open n UART serial data line. Is the action complete? | -- | -- | |
Can the scan tool communicate with the IPC? | -- | Go to Step 10 | Go to Section 8A-50 | |
10 |
Was a condition necessary to require a repair? | -- | Go to Step 13 | |
11 | Check to see if a PCM, IPC, or lock cylinder was replaced. Were any of these components replaced? | -- | Go to Step 12 | Go to Section 9D |
12 |
Does engine start and continue to run? | -- | Go to Step 2 | |
13 | Replace the PCM. Is action complete? | -- | -- | |
