Dtc U0100 Lost Communication With Ecm / Pcm A
Drivetrain. Hilux. Tgn26, 36 Kun25, 26, 35, 36 Ggn25
DESCRIPTION
WIRING DIAGRAM
INSPECTION PROCEDURE
CHECK ECM (+B VOLTAGE, E1 GROUND)
CHECK TCM (IG2 VOLTAGE, E1 GROUND)
CHECK HARNESS AND CONNECTOR (ECM - TCM)
CONFIRM DTC
DTC U0100 Lost Communication with ECM / PCM "A" |
DESCRIPTION
The Transmission Control Module (TCM) and ECM perform 2-way communications with each other via the Controller Area Network (CAN). The TCM sends signals to the ECM concerning required engine rpm, required engine torques, warning indicators in the combination meter, DTCs and other data. The ECM sends signals to the TCM concerning engine rpm, opening angles of the throttle valve, temperature of the intake air and engine coolant, engine torques, and other data.If the TCM cannot communicate with the ECM, the TCM will conclude that there is a malfunction in the CAN system, illuminate the MIL and set a DTC.DTC Code
| DTC Detection Condition
| Trouble Area
|
U0100
| No communication from ECM for certain period of time (1-trip detection logic)
| - Open or short in TCM and ECM circuit
- TCM
- ECM
|
WIRING DIAGRAM
INSPECTION PROCEDURE
- HINT:
- Read freeze frame data using the intelligent tester. Freeze frame data records the engine conditions when a malfunction is detected. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, and other data from the time the malfunction occurred.
- NOTICE:
- If the ECM is replaced, the new ECM needs initialization.
| 1.CHECK ECM (+B VOLTAGE, E1 GROUND) |
Measure the voltage according to the value(s) in the table below.
- Standard Voltage:
Tester Connection
| Switch Condition
| Specified Condition
|
G39-1 (+B) - Body ground
| Ignition switch ON
| 11 to 14 V
|
Turn the ignition switch off.
Measure the resistance according to the value(s) in the table below.
- Standard Resistance:
Tester Connection
| Condition
| Specified Condition
|
C23-7 (E1) - Body ground
| Always
| Below 1 Ω
|
Text in Illustration*a
| Rear view of wire harness connector
(to ECM)
|
ResultResult
| Proceed to
|
OK
| A
|
NG (ECD system w/ EGR cooler)
| B
|
NG (ECD system w/o EGR cooler)
| C
|
| 2.CHECK TCM (IG2 VOLTAGE, E1 GROUND) |
Measure the voltage according to the value(s) in the table below.
- Standard Voltage:
Tester Connection
| Switch Condition
| Specified Condition
|
G41-6 (IG2) - Body ground
| Ignition switch ON
| 11 to 14 V
|
Turn the ignition switch off.
Measure the resistance according to the value(s) in the table below.
- Standard Resistance:
Tester Connection
| Condition
| Specified Condition
|
C24-1 (E1) - Body ground
| Always
| Below 1 Ω
|
Text in Illustration*a
| Rear view of wire harness connector
(to TCM)
|
| 3.CHECK HARNESS AND CONNECTOR (ECM - TCM) |
Disconnect the G38 ECM connector.
Disconnect the G41 TCM connector.
Measure the resistance according to the value(s) in the table below.
- Standard Resistance:
Tester Connection
| Condition
| Specified Condition
|
G38-22 (CAN+) - G41-21 (CAN+)
| Always
| Below 1 Ω
|
G38-21 (CAN-) - G41-20 (CAN-)
| Always
| Below 1 Ω
|
G38-22 (CAN+) or G41-21 (CAN+) - Body ground
| Always
| 10 kΩ or higher
|
G38-21 (CAN-) or G41-20 (CAN-) - Body ground
| Always
| 10 kΩ or higher
|
| | REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
|
Clear the DTC.
Replace the TCM.
- HINT:
- Replace the TCM with a TCM from a normally functioning vehicle of the same model.
Start the engine.
Read the DTCs.
- Result:
Result
| Proceed to
|
U0100 is output
| A
|
U0100 is not output
| B
|
