Automatic Transmission/Transaxle

U1000 CAN COMM Circuit

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" with SDT or 17th judgment flicker without SDT 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 SDT

1 Turn ignition switch "ON". (Do not start engine.)
2 Select "Data list" mode for "AT" with SDT.
3 Start engine and wait for at least 6 seconds.
4 If DTC is detected, go to "Diagnosis Procedure".

with GST

Follow the procedure "WITH SDT".

Diagnosis Procedure

1. CHECK CAN COMMUNICATION CIRCUIT

With SDT
1 Turn ignition switch "ON" and start engine.
2 Select "DTC check" mode for "AT" with SDT.

Is any malfunction of the "U1000" indicated?
YES
Go to Section 10H. Refer to [LAN System: Basic Inspection] LAN System Basic Inspection.
NO
INSPECTION END