BR–156 BRAKE SYSTEM – TRACTION CONTROL SYSTEM (TRAC) DTC 53 ECM Communication Circuit Malfunction CIRCUIT DESCRIPTION This circuit is used to send TRAC control information from the TRAC ECU to the ECM (TRC+, TRC–), and engine control information from the ECM to the TRAC ECU (EFI+, EFI–). DTC No. | Diagnostic Trouble Code Detecting Condition | Trouble area 53 | Either of the following (1) or (2) continues for 5 sec.: (1) A signal is received from the ECM indicating trouble in the TRC+ or TRC– circuit. (2) No EFI ± data is received from the ECM when the engine speed is 500 RPM or more, or the vehicle speed is 60 km/h (37 mph) or more. | Open or short in TRC+ or TRC– circuit Open or short in EFI+ or EFI– circuit ECM TRAC ECU WIRING DIAGRAM ECM 5 V EFI+ 27 B 3 EFI+ E10 T10 EFI– 26 W 8 EFI– E10 T10 TRC+ 14 O 2 TRC+ E10 T10 5 V TRC– 13 W-R 9 TRC– E10 T10 TRAC ECU RO7235 INSPECTION PROCEDURE HINT: When the TRAC indicator light is ON, there is a problem in the EFI ± circuit, and when the TRAC indicator light is OFF, there is a problem in the TRC ± circuit. 1 Check for open and short n harness and connector between terminals EFI+, EFI–, TRAC+ and TRC– of ECU and ECM (See page IN–30). OK NG Repair or replace harness or connector. Check and replace ECM or TRAC ECU.