Toyota 4Runner: Lost Communication with ECM / PCM "A" (U0100)
DESCRIPTION
|
DTC Code |
DTC Detection Condition |
Trouble Area |
|---|---|---|
|
U0100 |
There is no communication from the ECM. |
|
HINT:
For vehicles with a smart key system only.
WIRING DIAGRAM
CAUTION / NOTICE / HINT
NOTICE:
Inspect the fuses for circuits related to this system before performing the following inspection procedure.
HINT:
Operating the ignition switch, any switches or any doors triggers related ECU and sensor communication with the CAN, which causes resistance variation.
PROCEDURE
|
1. |
DISCONNECT CABLE FROM NEGATIVE BATTERY TERMINAL |
(a) Disconnect the cable from the negative (-) battery terminal before measuring the resistances of the main wire and branch wire.
CAUTION:
Wait at least 90 seconds after disconnecting the cable from the negative (-) battery terminal to disable the SRS system.
NOTICE:
When disconnecting the cable, some systems need to be initialized after the cable
is reconnected (See page .gif)
).
|
.gif)
|
2. |
CHECK FOR OPEN IN CAN BUS MAIN WIRE (ECM MAIN WIRE) |
|
(a) Disconnect the F50 ECM connector. |
|
.png)
(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
|
Tester Connection |
Switch Condition |
Specified Condition |
|---|---|---|
|
F50-34 (CANP) - F50-33 (CANN) |
Ignition switch off |
108 to 132 Ω |
|
*a |
Rear view of wire harness connector (to ECM) |
| NG | .gif) |
REPAIR OR REPLACE ECM MAIN WIRE OR CONNECTOR (CANP, CANN) |
|
|
3. |
CHECK HARNESS AND CONNECTOR (ECM - BATTERY AND BODY GROUND) |
(a) Connect the cable to the negative (-) battery terminal.
NOTICE:
When disconnecting the cable, some systems need to be initialized after the cable
is reconnected (See page ).
Text in Illustration
|
*a |
Front view of wire harness connector (to ECM) |
- |
- |
(b) Disconnect the B38, B39 and F51 ECM connectors.
(c) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
|
Tester Connection |
Condition |
Specified Condition |
|---|---|---|
|
B38-12 (E1) - Body ground |
Always |
Below 1 Ω |
|
B39-14 (E01) - Body ground |
Always |
Below 1 Ω |
|
B39-15 (E02) - Body ground |
Always |
Below 1 Ω |
|
B39-10 (ME01) - Body ground |
Always |
Below 1 Ω |
|
F51-12 (EC) - Body ground |
Always |
Below 1 Ω |
(d) Measure the voltage according to the value(s) in the table below.
Standard Voltage:
|
Tester Connection |
Condition |
Specified Condition |
|---|---|---|
|
F51-24 (BATT) - Body ground |
Always |
11 to 14 V |
|
F51-23 (+B2) - Body ground |
Battery positive (+) voltage applied to terminal F51-9 (MREL) |
11 to 14 V |
|
F51-22 (+B) - Body ground |
Battery positive (+) voltage applied to terminal F51-9 (MREL) |
11 to 14 V |
| OK | |
REPLACE ECM |
| NG | |
REPAIR OR REPLACE HARNESS OR CONNECTOR |
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DTC Detection Condition
Trouble Area
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