Toyota Avalon (XX50): Transmission Control Switch Circuit. Lost Communication with ECM/PCM "A" Missing Message (U010087). Vehicle Control History

Toyota Avalon (XX50) 2019-2022 Service & Repair Manual / Drivetrain / Ua80e Automatic Transmission / Transaxle / Automatic Transaxle System / Transmission Control Switch Circuit. Lost Communication with ECM/PCM "A" Missing Message (U010087). Vehicle Control History

Transmission Control Switch Circuit

DESCRIPTION

When the shift lever is in S and moved toward "-" or "+", it is possible to select different shift ranges (S1 to S8).

Moving the shift lever toward "+" increases the shift range by one, and moving the shift lever toward "-" decreases the shift range by one.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

Inspect the fuses for circuits related to this system before performing the following procedure.

PROCEDURE

1.

READ VALUE USING TECHSTREAM (Shift SW Status (S Range))

(a) Connect the Techstream to the DLC3.

(b) Turn the engine switch on (IG).

(c) Turn the Techstream on.

(d) Enter the following menus: Powertrain / Engine / Data List / Shift SW Status (S Range).

(e) Read the Data List according to the display on the Techstream.

Powertrain > Engine > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

Shift SW Status (S Range)

Sport (S) mode select switch status

ON or OFF
  • ON: Shift lever in S, "+" or "-"
  • OFF: Shift lever not in S, "+" or "-"

-
Powertrain > Engine > Data List

Tester Display

Shift SW Status (S Range)

Result

Proceed to

Data List value is normal

A

Data List value is not normal

B
B

GO TO STEP 6

A

2.

READ VALUE USING TECHSTREAM (SPORT SHIFT UP SW AND SPORT SHIFT DOWN SW)

(a) Connect the Techstream to the DLC3.

(b) Turn the engine switch on (IG).

(c) Turn the Techstream on.

(d) Enter the following menus: Powertrain / Engine / Data List / Sport Shift Up SW and Sport Shift Down SW.

(e) Read the Data List according to the display on the Techstream.

Powertrain > Engine > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

Sport Shift Up SW

Sport shift up switch status

ON or OFF
  • ON: Shift lever held in "+" or "+" shift paddle switch operated
  • OFF: Shift lever not held in "+" and "+" shift paddle switch released

-

Sport Shift Down SW

Sport shift down switch status

ON or OFF
  • ON: Shift lever held in "-" or "-" shift paddle switch operated
  • OFF: Shift lever not held in "-" and "-" shift paddle switch released

-
Powertrain > Engine > Data List

Tester Display

Sport Shift Up SW

Sport Shift Down SW

Result

Proceed to

Data List values are normal

A

Data List values are not normal

B
A

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

B

3.

INSPECT TRANSMISSION CONTROL SWITCH (SHIFT LOCK CONTROL UNIT ASSEMBLY)

(a) Disconnect the G22 transmission control switch connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

3 (SFTU) - 2 (E)

Shift lever held in "+" (Up shift)

Below 1 Ω

Shift lever not held in "+" (Up shift)

10 kΩ or higher

1 (SFTD) - 2 (E)

Shift lever held in "-" (Down shift)

Below 1 Ω

Shift lever not held in "-" (Down shift)

10 kΩ or higher

*a

Component without harness connected

(Transmission Control Switch (Shift Lock Control Unit Assembly))
NG

REPLACE TRANSMISSION CONTROL SWITCH (SHIFT LOCK CONTROL UNIT ASSEMBLY)

OK

4.

CHECK HARNESS AND CONNECTOR (TRANSMISSION CONTROL SWITCH - BODY GROUND)

(a) Disconnect the G22 transmission control switch connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

G22-2 (E) - Body ground

Always

Below 1 Ω
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (TRANSMISSION CONTROL SWITCH - BODY GROUND)
OK

5.

CHECK HARNESS AND CONNECTOR (TRANSMISSION CONTROL SWITCH - ECM)

(a) Connect the G22 transmission control switch connector.

(b) Disconnect the A18 ECM connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

A18-38 (SFTU) - Body ground

Shift lever held in "+" (Up shift)

Below 1 Ω

A18-38 (SFTU) - Body ground

Shift lever not held in "+" (Up shift)

10 kΩ or higher

A18-37 (SFTD) - Body ground

Shift lever held in "-" (Down shift)

Below 1 Ω

A18-37 (SFTD) - Body ground

Shift lever not held in "-" (Down shift)

10 kΩ or higher
OK

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (TRANSMISSION CONTROL SWITCH - ECM)

6.

INSPECT TRANSMISSION CONTROL SWITCH (SHIFT LOCK CONTROL UNIT ASSEMBLY)

(a) Disconnect the G22 transmission control switch connector.

*a

Component without harness connected

(Transmission Control Switch (Shift Lock Control Unit Assembly))

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

4 (IG) - 5 (S)

Shift lever in S, "+" or "-"

Below 1 Ω

Shift lever not in S, "+" or "-"

10 kΩ or higher
NG

REPLACE TRANSMISSION CONTROL SWITCH (SHIFT LOCK CONTROL UNIT ASSEMBLY)

OK

7.

CHECK HARNESS AND CONNECTOR (TRANSMISSION CONTROL SWITCH (POWER SOURCE))

(a) Disconnect the G22 transmission control switch connector.

(b) Turn the engine switch on (IG).

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

G22-4 (IG) - Body ground

Engine switch on (IG)

11 to 14 V
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (TRANSMISSION CONTROL SWITCH (POWER SOURCE))
OK

8.

CHECK HARNESS AND CONNECTOR (TRANSMISSION CONTROL SWITCH - ECM)

(a) Disconnect the G22 transmission control switch connector.

(b) Disconnect the A18 ECM connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

G22-5 (S) - A18-17 (S)

Always

Below 1 Ω

G22-5 (S) or A18-17 (S) - Body ground and other terminals

Always

10 kΩ or higher
OK

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (TRANSMISSION CONTROL SWITCH - ECM)

Lost Communication with ECM/PCM "A" Missing Message (U010087)

DESCRIPTION

The engine control unit and transmission control unit are located inside the ECM. The engine control unit intercommunicates with the transmission control unit using CAN communication.

If there is a problem in this intercommunication, the ECM stores this DTC.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

MIL

Memory

Note

U010087

Lost Communication with ECM/PCM "A" Missing Message

While the engine switch is on (IG), there is no communication between the engine control unit and transmission control unit for 1.25 seconds or more (1-trip detection logic).

ECM

Comes on

DTC stored

SAE Code:

U0100

MONITOR STRATEGY

Related DTCs

U0100: Verify communication

Required sensors/components (Main)

ECM

Required sensors/components (Related)

-

Frequency of Operation

Continuous

Duration

1.25 sec.

MIL Operation

Immediately

Sequence of Operation

None

TYPICAL ENABLING CONDITIONS

The monitor will run whenever the following DTCs are not stored

None

Battery Voltage

10.5 V or more

Engine switch

On (IG)

Starter

Off

TYPICAL MALFUNCTION THRESHOLDS

Communication signal

Lost communication with ECM/PCM

CONFIRMATION DRIVING PATTERN

HINT:

  • After repairs have been completed, clear the DTCs and then check that the vehicle has returned to normal by performing the following All Readiness check procedure.
  • When clearing the permanent DTCs, refer to the Clear Permanent DTC procedure.

    Click here

  1. Connect the Techstream to the DLC3.
  2. Turn the engine switch on (IG) and turn the Techstream on.
  3. Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
  4. Turn the engine switch off and wait for 2 minutes or more.
  5. Turn the engine switch on (IG) and turn the Techstream on.
  6. Wait for 2 seconds or more with the engine switch on (IG). [*1]

    HINT:

    [*1] : Normal judgment procedure.

    The normal judgment procedure is used to complete DTC judgment and also used when clearing permanent DTCs.

  7. Enter the following menus: Powertrain / Transmission / Utility / All Readiness.
  8. Input the DTC: U010087.
  9. Check the DTC judgment result.

    Techstream Display

    Description

    NORMAL
    • DTC judgment completed
    • System normal

    ABNORMAL
    • DTC judgment completed
    • System abnormal

    INCOMPLETE
    • DTC judgment not completed
    • Perform driving pattern after confirming DTC enabling conditions

    N/A
    • Unable to perform DTC judgment
    • Number of DTCs which do not fulfill DTC preconditions has reached ECU memory limit

    HINT:

    • If the judgment result shows NORMAL, the system is normal.
    • If the judgment result shows ABNORMAL, the system has a malfunction.
    • If the judgment result shows INCOMPLETE or N/A, perform the normal judgment procedure again.

CAUTION / NOTICE / HINT

NOTICE:

  • Perform the universal trip to clear permanent DTCs.

    Click here

  • Perform registration and/or initialization when parts related to the automatic transaxle are replaced.

    Click here

PROCEDURE

1.

CHECK OTHER DTC OUTPUT (IN ADDITION TO DTC U010087)

(a) Connect the Techstream to the DLC3.

(b) Turn the engine switch on (IG).

(c) Turn the Techstream on.

(d) Enter the following menus: Powertrain / Transmission / Trouble Codes.

Powertrain > Transmission > Trouble Codes

(e) Read the DTCs using the Techstream.

Result

Proceed to

Only DTC U010087 is output

A

DTC U010087 and other DTCs are output

B
B

GO TO DTC CHART

A

2.

REPLACE ECM

(a) Replace the ECM.

Click here

NEXT

PERFORM REGISTRATION

Vehicle Control History

VEHICLE CONTROL HISTORY

VEHICLE CONTROL HISTORY

HINT:

A part of the control history can be confirmed using the vehicle control history.

Click here

System Description. System Diagram. Terminals Of Ecm

Automatic Transaxle Unit

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