Toyota Tacoma manuals

Toyota Tacoma 2015-2018 Service Manual: ECM Communication Circuit Malfunction (C1203)

DESCRIPTION

The circuit is used to send TRAC and VSC control information from the skid control ECU (brake actuator assembly) to the ECM, and engine control information from the ECM to the skid control ECU (brake actuator assembly) through the CAN communication system.

for 4WD or w/ Rear Differential Lock:

The rear differential lock identification signal is sent from the 4 wheel drive control ECU to the skid control ECU (brake actuator assembly) via the CAN communication system.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

C1203

ECM Communication Circuit Malfunction

Any of the following is detected:

  • Engine model information sent from the ECM does not match the information stored in the skid control ECU.
  • The rear differential lock identification signal sent from the 4 wheel drive control ECU does not match the information stored in the skid control ECU.*
  • No system information stored in the skid control ECU.
  • Incorrect installation of the skid control ECU, 4 wheel drive control ECU* or ECM.
  • ECM malfunction or ECM with incorrect part number installed
  • 4 wheel drive control ECU malfunction or 4 wheel drive control ECU with incorrect part number installed*
  • Skid control ECU (Brake actuator assembly)
  • *: for 4WD or w/ Rear Differential Lock

HINT:

DTC will be output when conditions for any of the patterns in the table above are met.

CAUTION / NOTICE / HINT

NOTICE:

When replacing the skid control ECU (brake actuator assembly), perform zero point calibration and store system information (See page HINT: HINT: ).

HINT:

When DTC C1203, inspect and repair the trouble areas indicated.

PROCEDURE

1.

CHECK PART NUMBER (ECM)

(a) Check that the proper ECM is installed.

Result

Result

Proceed to

Proper ECM is installed (for 4WD or w/ Rear Differential Lock)

A

Proper ECM is installed (except 4WD or w/o Rear Differential Lock)

B

Proper ECM are not installed

C

B

GO TO STEP 3

C

CHECK OR REPLACE CHARGING SYSTEM OR BATTERY

A

2.

CHECK PART NUMBER (4 WHEEL DRIVE CONTROL ECU)

(a) Check that a proper 4 wheel drive control ECU is installed.

Result

Result

Proceed to

Proper 4 wheel drive control ECU is installed

A

Proper 4 wheel drive control ECU are not installed

B

B

REPLACE 4 WHEEL DRIVE CONTROL ECU

A

3.

CHECK BRAKE ACTUATOR ASSEMBLY

(a) Check if the brake actuator assembly had been replaced before the DTC was recorded.

Result

Result

Proceed to

The brake actuator assembly is not replaced

A

The brake actuator assembly is replaced

B

B

GO TO STEP 5

A

4.

RECONFIRM DTC

(a) Clear the DTC (See page ). (b) Turn the ignition switch off. ).

(b) Turn the ignition switch off.

(c) Check if the same DTC is recorded (See page Result Result ).

Result

Result

Proceed to

DTC C1203 is not output

A

DTC C1203 is output

B

A

USE SIMULATION METHOD TO CHECK

B

REPLACE BRAKE ACTUATOR ASSEMBLY

5.

PERFORM INITIALIZATION AND CALIBRATION

(a) Perform initialization and calibration (See page ).

NEXT

6.

RECONFIRM DTC

(a) Clear the DTC (See page ). (b) Turn the ignition switch off. ).

(b) Turn the ignition switch off.

(c) Check if the same DTC is recorded (See page Result Result ).

Result

Result

Proceed to

DTC C1203 is not output

A

DTC C1203 is output

B

A

END

B

REPLACE BRAKE ACTUATOR ASSEMBLY

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