Up to 08/2009

NETWORKING: CAN COMMUNICATION SYSTEM: U0100: Lost Communication with ECM / PCM
U0100 - Lost Communication with ECM / PCM

DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

NOTICE:
* Turn the engine switch off before measuring the resistances between CAN bus main wires and between CAN bus branch wires.
* Turn the engine switch off before inspecting CAN bus wires for a ground short.
* After the engine switch is turned off, check that the key reminder warning system and light reminder warning system are not operating.
* Before measuring the resistance, leave the vehicle as is for at least 1 minute and do not operate the engine switch, any other switches or the doors. If any doors need to be opened in order to check connectors, open the doors and leave them open.
HINT
* Operating the engine switch, any other switches or a door triggers related ECU and sensor communication on the CAN. This communication will cause the resistance value to change.
* Even after DTCs are cleared, if a DTC is stored again after driving the vehicle for a while, the malfunction may be occurring due to vibration of the vehicle. In such a case, wiggling the ECUs or wire harness while performing the inspection below may help determine the cause of the malfunction.
PROCEDURE

1. RECONFIRM DTC OUTPUT

(a) Reconfirm DTCs.

HINT
If CAN power management bus DTC U1002 is output from the power management control ECU (Techstream display/Power Management2), troubleshoot for U1002 and check for malfunctions in the power management main bus circuit.

Result:

B -- REPAIR CIRCUITS INDICATED BY OUTPUT DTCS U1002
A -- Continue to next step.

2. CHECK CAN BUS WIRE FOR DISCONNECTION (ECM MAIN WIRE/POWER MANAGEMENT BUS)

(a) Turn the engine switch off.

(b) Disconnect the ECM connector.

Text in Illustration

NG -- REPAIR OR REPLACE CAN BUS MAIN WIRE OR CONNECTOR (ECM MAIN WIRE)
OK -- Continue to next step.

3. CHECK HARNESS AND CONNECTOR (POWER SOURCE TERMINAL)

(a) Measure the voltage according to the value(s) in the table below.

Standard Voltage:

Text in Illustration

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT)
OK -- Continue to next step.

4. CHECK HARNESS AND CONNECTOR (GROUND TERMINAL)

(a) Disconnect the ECM connector.

Text in Illustration

(b) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (GROUND CIRCUIT)

OK -- REPLACE ECM Removal