DTC 3
DTC 3 ECM COMMUNICATION ERRORComponent Location:
GENERAL DESCRIPTION
The immobilizer system consists of a mutual authentication transponder inside the key head, a stand alone antenna, the BCM unit and the EMS. The BCM unit shall emulate the original immobilizer to EMS protocol as closely as possible.
In the Stand alone immobilizer system, the immobilizer is contained within the BCM. The EMS shall request the BCM for permission to start the vehicle. The BCM shall perform the immobilization functions and reply "start" or no start permission to the EMS.
The communication between the BCM and EMS for the purposes of immobilization for the stand alone will be via the "W Line".
DTC DESCRIPTION
This DTC indicates that Request from ECM is Invalid or corrupted data.
DTC Detecting Condition:
Schematic Diagram:
MONITOR SCANTOOL DATA
1. Ignition "ON" & Engine "OFF".
2. Select Diagnostic Trouble Codes (DTCs)" mode and Clear the DTC.
3. Is the DTC erased?
YES
- Fault is intermittent caused by poor contact in the BCM and/or the antenna coil connector or was repaired and BCM memory was not cleared. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.
- Repair or replace as necessary and then go to "Verification of Vehicle Repair" procedure.
NO - Go to "W/Harness Inspection" procedure.
TERMINAL AND CONNECTOR INSPECTION
1. Many malfunctions in the electrical system are caused by poor harness and terminals.
Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.
2. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.
3. Has a problem been found?
YES - Repair as necessary and go to "Verification of Vehicle Repair" procedure.
NO - Go to "Power Circuit Inspection" procedure.
SIGNAL CIRCUIT INSPECTION
1. Check for open in harness
1. Ignition "OFF".
2. Disconnect BCM and ECM connector
3. Measure resistance between terminal 20 of the BCM harness connector and terminal 3 of the ECM harness connector.
Specification : Approx. below 1 ohm
4. Is the measured resistance within specifications?
YES - Go to "Component Inspection" procedure.
NO
- Check for open in signal harness.
- Repair as necessary and go to "Verification of Vehicle Repair" procedure.
COMPONENT INSPECTION
1. Check ECM
1. Ignition "ON" & Engine "OFF".
2. Perform Key teaching/changing mode again.
3. Is the Key teaching completed?
YES - Go to "Verification of Vehicle Repair" procedure.
NO
- Substitute with a known-good ECM (must be neutralized or Virgin ECM) and check for proper operation.
- If the problem is corrected, replace ECM and then go to "Verification of Vehicle Repair" procedure.
NOTE: Don't forget to prepare for the PIN code.
VERIFICATION OF VEHICLE REPAIR
After a repair, it is essential to verify that the fault has been corrected.
1. Connect scan tool and monitor CURRENT DATA to check No. of Learnt key, ECM and KEY status.
2. Select "Diagnostic Trouble Codes (DTCs)" mode and Clear the DTCs.
3. Are any DTCs present?
YES - Go to the applicable troubleshooting procedure.
NO - System is performing to specification at this time.