B2784

DTC B2784

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.

DTC Descriptor
DTC B2784
- Antenna Coil Open/Short

Circuit Description

The transponder key coil is built into the theft deterrent key transponder amplifier and receives a key code signal from the transponder chip in the key. This signal is amplified by the amplifier, then it is sent to the theft deterrent key transponder assembly.

Conditions for Running the DTC

The key is inserted into the ignition cylinder.

Conditions for Setting the DTC

The antenna coil is open or shorted to ground.

Action Taken When the DTC Sets

Engine starting will be disabled.

Conditions for Clearing the DTC

The DTC will clear when the conditions for setting the DTC have been corrected.

Reference Information
Schematic Reference

Immobilizer Schematics (Immobilizer Schematics)
Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

Immobilizer Description and Operation (Immobilizer Description and Operation)
Electrical Information Reference

* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)

Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information

Circuit/System Verification

Ignition ON, observe the scan tool Antenna 1 Status parameter. The reading should be Normal.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the theft deterrent key transponder amplifier.
2. No key in ignition cylinder, test for less than 1V between the 5 volt reference circuit terminal 14 and ground.

• If greater than the specified range, test the 5 volt reference circuit for a short to voltage. If the circuit tests normal, replace the theft deterrent key transponder

3. Key in ignition cylinder, test for 4.6-5.4V between the 5 volt reference circuit terminal 14 and ground.

• If greater than the specified range, test the 5 volt reference circuit for a short to voltage. If the circuit tests normal, replace the theft deterrent key transponder.
• If less than the specified range, test the 5 volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the theft deterrent key transponder.

4. Key in ignition cylinder, test for 4.6-5.4V between the 5 volt reference circuit terminal 14 and the low reference circuit terminal 5. If the circuit tests normal, replace the theft deterrent key transponder.

• If not within the specified range, test the low reference circuit for an open/high resistance.

5. If all circuits test normal, replace the theft deterrent key transponder amplifier.

Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Theft Deterrent Key Transponder Amplifier Replacement (Service and Repair)
* Control Module References (Programming and Relearning) for theft deterrent key transponder replacement, setup, and programming