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

Engine Control System Malfunction (C1201)
DESCRIPTION If a malfunction in the engine control system is detected, VSC and TRAC operations are prohibited by the fail-safe function. DTC No. Detection Item DTC ...

ABS Warning Light does not Come ON
DESCRIPTION The skid control ECU (brake actuator assembly) is connected to the combination meter assembly via CAN communication. WIRING DIAGRAM Refer to ABS Warning Light Remains ON (See page ) ...

Other materials:

Vehicle Speed Sensor Circuit (C1AA3)
DESCRIPTION The forward recognition camera receives vehicle speed signals from the skid control ECU. If the skid control ECU receives a vehicle speed sensor malfunction signal, it informs the forward recognition camera via CAN communication, and DTC C1AA3 is stored. DTC No. ...

Symbols used in illustrations
The symbol of a circle with a slash through it means “Do not”, “Do not do this”, or “Do not let this happen”. Arrows indicating operations Indicates the action (pushing, turning, etc.) used to operate switches and other devices. Indicates the outcome of an operation (e.g. a ...

Installation
INSTALLATION PROCEDURE 1. INSTALL FRONT DIFFERENTIAL CARRIER ASSEMBLY (a) Connect the actuator hose and connector. (b) Install the No. 1 mounting support with the 3 bolts. Torque: 186 N·m {1899 kgf·cm, 138 ft·lbf} (c) Install the No. 2 mounting support with the 2 bolts. Torque: 160 N ...

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