DTC C1203: ECM Communication Circuit Malfunction; DTC C1270: Initialization Incomplete (Test Mode DTC): Procedure

WARNING: This page is about a different car, the 2009 Lexus IS 350 and 2009 Lexus IS 250. However, it is still accessible from the selected car via links, so may be relevant.

CHECK PART NUMBER (ECM)

Check that the part number of the installed ECM is correct.

OK

ECM installed in the vehicle has the correct part number.

Result

Result	Proceed to
OK	A
NG (for 2GR-FSE)	B
NG (for 4GR-FSE)	C

C → See step 6

B → See step 5

A: Go to next step

CLEAR AND STORE SYSTEM INFORMATION
1. Clear the system information. Refer to CALIBRATION .
2. Store the system information. Refer to CALIBRATION .
NEXT: Go to next step

RECONFIRM DTC

Clear the DTCs. Refer to DTC CHECK / CLEAR .

Check if the same DTC is recorded. Refer to DTC CHECK / CLEAR .

Result

Result	Proceed to
DTC (C1203) is not output	A
DTC (C1203) is output	B

B → See step 7

A → See step 4

CHECK FOR INTERMITTENT PROBLEMS. Refer to ELECTRONIC CIRCUIT INSPECTION PROCEDURE
REPLACE ECM (for 2GR-FSE). Refer to REMOVAL
REPLACE ECM (for 4GR-FSE). Refer to REMOVAL
REPLACE BRAKE ACTUATOR ASSEMBLY. Refer to REMOVAL