B1A28

B1A28-ECM MISMATCH WITH SKIM

For a complete wiring diagram, refer to the Wiring Information.

Theory of Operation

For the engine to start, the Sentry Key Immobilizer (SKIM) feature of the Wireless Ignition Node (WIN) and the Powertrain Control Module (PCM) must successfully communicate data over the data bus. Once the WIN sends the message that a valid Fob-Integrated-Key (FOBIK) is being used, the PCM and WIN perform a "handshake" routine, encrypted with the VIN, to validate this information, and a match allows the engine to run when the ignition state transitions to START. The repair of this fault is determined by the ability of the WIN and PCM/ECM to complete a successful handshake routine over the bus.

- When Monitored:
Whenever a valid FOBIK is inserted in the basestation and turned to the ON position, the WIN/PCM handshake takes place. The WIN validates that the message is sent to and received by the PCM.

- Set Condition:
When a valid FOBIK is used and the WIN receives a mismatching cryptology code from the PCM as part of the routine, the WIN will send the command to flash the Security warning lamp and set this DTC as active. The engine will not start and the DTC will remain active until the WIN and PCM complete a successful handshake.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Wireless Ignition Node (WIN) Pre-Diagnostic Procedure.

1. DETERMINE ACTIVE OR STORED DIAGNOSTIC TROUBLE CODE (DTC)

Is the DTC active or stored?

WIN - ACTIVE DTC

- Go To 2

WIN - STORED DTC

- Perform the WIN INTERMITTENT TEST. Wireless Ignition Node (WIN) Intermittent Condition Test

2. VERIFY THE VEHICLE IDENTIFICATION NUMBER (VIN) STORED IN THE POWERTRAIN CONTROL MODULE (PCM).
1. Using the scan tool, access the VIN number stored in the PCM.

NOTE: Make sure that a VIN has been programmed into the PCM. If a VIN is not displayed, attempt to program the PCM with the correct VIN before continuing.

2. Compare the VIN displayed, with the VIN of the vehicle.

Does the VIN recorded in the PCM match the VIN of the vehicle?

Yes

- Using the scan tool, verify the VIN in the WIN matches the VIN of the vehicle. If it DOES, Go To 3 If it does NOT match, replace the Wireless Ignition Node. Prior to replacing the WIN, the RUN circuits must be checked at the PCM. A missing run circuit at the PCM can cause this DTC to set.
- Replace the Wireless Ignition Node (WIN). Wireless Ignition Node Receiver - Removal.
- Perform the WIN VERIFICATION TEST. Wireless Ignition Node (WIN) Verification Test.

No

- Using the scan tool, perform the PCM Replaced Procedure to update the VIN in the PCM. Then, Go To 3

3. PCM STARTING DTCs
1. Use the scan tool and erase all DTCs in the WIN and PCM.
2. Turn the Ignition Off, and wait 15 seconds before turning the Ignition On.
3. Try to start the engine. If the engine starts, leave it run for one minute and then turn the engine off (ignition on)
4. Wait one minute, and read the active PCM DTCs.

Does the scan tool display any Starting related DTCs?

Yes

- Testing and Inspection Perform the appropriate Diagnostic Procedure.

No

- Go To 4

4. VERIFY PCM PROGRAMMING
1. Use the scan tool and erase all DTCs in the WIN and PCM.
2. Turn the Ignition Off, and wait 15 seconds before turning the Ignition On.
3. Wait one minute, and read the active WIN DTCs.

Does the scan tool display: B1A28-ECM MISMATCH WITH SKIM as active?

Yes

- Replace and program the Powertrain Control Module. PCM/ECM Reprogramming
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Repair is complete.
- Perform the BODY VERIFICATION TEST. Body Verification Test.