Transmission Control Systems

DTC U1000 CAN COMMUNICATION LINE

Description
CAN (Controller Area Network) is a serial communication line for real time application. It is an on-vehicle multiplex communication line with high data communication speed and excellent malfunction detection ability. Many electronic control units are equipped onto a vehicle, and each control unit shares information and links with other control units during operation (not independent). In CAN communication, control units are connected with 2 communication lines (CAN-H line, CAN-L line) allowing a high rate of information transmission with less wiring. Each control unit transmits/receives data but selectively reads required data only.

On Board Diagnosis Logic
^ This is an OBD-II self-diagnostic item.
^ Diagnostic trouble code "U1000 CAN COMM CIRCUIT" with CONSULT-II or 17th judgement flicker without CONSULT-II is detected when TCM cannot communicate to other control units.

Possible Cause
Harness or connectors
(CAN communication line is open or shorted.)

DTC Confirmation Procedure

NOTE: If "DTC Confirmation Procedure" has been previously performed, always turn ignition switch OFF and wait at least 10 seconds before performing the next test.

After the repair, perform the following procedure to confirm the malfunction is eliminated.

With CONSULT-II





1. Turn ignition switch ON.
2. Select "ECU INPUT SIGNALS" or "MAIN SIGNALS" in "DATA MONITOR" mode for "A/T" with CONSULT-II.
3. Start engine and wait for at least 6 seconds.
4. If DTC is detected, go to AT-106, "Diagnostic Procedure"

With GST
Follow the procedure "WITH CONSULT-II".

AT-CAN-01:

Wiring Diagram - AT - CAN





Diagnostic Procedure

1. CHECK CAN COMMUNICATION CIRCUIT

With CONSULT-II
1. Turn ignition switch ON and start engine.





2. Select "SELF-DIAG RESULTS" mode for "A/T" with CONSULT-II.
Is any malfunction of the "U1000 CAN COMM CIRCUIT" indicated?
YES >> Print out CONSULT-II screen, go to LAN section. Refer to LAN-49, "CAN System Specification Chart". CAN System Specification Chart
NO >> INSPECTION END