Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
DTC Descriptors
DTC B2947: Security System Sensor Power Circuit LowDTC B2948: Security System Sensor Power Circuit High
DTC B2955: Security System Sensor Data Circuit
DTC B2960: Security System Sensor Data Incorrect but Valid
DTC B3055: No Transponder Modulation or No Transponder
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Security System Sensor Supply Voltage | B2947 | B2947 | B2948 | -- |
Security System Sensor Signal | B2955 | B3055 | B2955 | -- |
Security System Sensor Low Reference | -- | B3055 | B3055 | -- |
Circuit/System Description
When the ignition is switched to the ON position, the theft deterrent module (TDM) supplies 12 volts to the theft deterrent exciter module. The TDM also provides a low reference for the exciter. With the voltage supplied to the exciter, the transponder embedded in the head of the key is energized by the exciter coils surrounding the ignition lock cylinder. The energized transponder transmits a signal that contains its unique value, which is received by the TDM via the security system sensor signal . The TDM then compares this value to a value stored in memory, the learned key code. If the value received matches the stored value, the TDM sends the fuel enable password to the engine control module/powertrain control module (ECM/PCM) via serial data.
Conditions for Running the DTC
B2947, B2955, B2960, B3055
The ignition is in the ACCY or RUN position.
B2948
The ignition is OFF.
Conditions for Setting the DTC
B2947
Voltage seen by the TDM at the security system sensor supply voltage circuit is less than the expected value.
B2948
Voltage seen by the TDM at the security system sensor supply voltage circuit is greater than the expected value.
B2955
Voltage seen by the TDM at the security system sensor signal circuit is not within the specified range.
B2960
Voltage seen by the TDM at the security system sensor signal circuit is within the specified range, but not the learned value.
B3055
The TDM is unable to measure the ignition key transponder value.
Action Taken When the DTC Sets
| • | Vehicle starting will be disabled. |
| • | The security indicator will be illuminated. |
Conditions for Clearing the DTC
| • | A current DTC will be cleared when the TDM detects the fault is no longer present. |
| • | A history DTC will be cleared after 100 malfunction-free ignition cycles. |
Reference Information
Schematic Reference
Connector End View Reference
Description and Operation
Immobilizer Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
Important: When using this diagnostic, more than one vehicle key is required to ensure proper diagnosis. If more than one key is not available at the time of service, contact the customer and ask if any other keys can be provided for service. If unavailable, a new second key can be created.
- Inspect all available vehicle keys that they are correct vehicle keys.
- While viewing the scan tool TDM Transponder Key parameter, turn ON the ignition with each of the available vehicle keys. The parameter should read Present with all available keys.
| ⇒ | If not a correct vehicle key, replace the key. |
| ⇒ | If only one key results in the parameter reading Not Present, replace the appropriate key. |
| ⇒ | If all available keys result in the parameter reading Not Present, refer to Exciter Circuit Malfunction. |
Circuit/System Testing
Exciter Circuit Malfunction
- Ignition OFF, disconnect the harness connector at the theft deterrent exciter.
- Ignition OFF, test for less than 10 ohms between the low reference circuit terminal C and ground.
- Ignition OFF, test for less than 1 volt between the supply voltage circuit terminal A and ground.
- Ignition ON, test for B+ between the supply voltage circuit terminal A and ground.
- Ignition OFF, disconnect the harness connector at the TDM.
- Ignition ON, verify a test lamp does not illuminate between the signal circuit terminal B and ground.
- Verify a test lamp does not illuminate between the signal circuit terminal B and B+.
- Test for 2 ohms between the signal circuit terminal B at the TDM harness connector at the signal circuit terminal B at the theft deterrent excite harness connector.
- Connect the harness connector at the theft deterrent exciter and the TDM.
- Ignition ON, verify the scan tool VTD States parameter does not display No Coded Key.
- If all circuits test normal, replace the TDM.
| ⇒ | If greater than the specified range test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the TDM. |
| ⇒ | If greater than the specified range, test the supply voltage circuit for a short to voltage. If the circuit tests normal, replace the TDM. |
| ⇒ | If not the specified value, test the supply voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the TDM. |
| ⇒ | If the test lamp illuminates, test the signal circuit for a short to voltage. |
| ⇒ | If the test lamp illuminates, test the signal circuit for a short to ground. |
| ⇒ | If not within the specified range, test the signal circuit for an open/high resistance. |
| ⇒ | If not the specified value, replace the theft deterrent exciter. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for TDM replacement, setup, and programming |
