Last Modified: 07-31-2024 6.11:8.1.0 Doc ID: RM100000001G70I
Model Year Start: 2020 Model: Corolla Prod Date Range: [01/2019 - 04/2020]
Title: METER / GAUGE / DISPLAY: METER / GAUGE SYSTEM (for HV Model): Speed Signal Circuit; 2020 MY Corolla Corolla HV [01/2019 - 04/2020]

Speed Signal Circuit

DESCRIPTION

The combination meter assembly receives the vehicle speed signal from this circuit. The wheel speed sensors produce an output that varies according to the vehicle speed. The wheel speed sensor output is received by the control ECU (brake booster with master cylinder assembly) which uses this information to create the vehicle speed signal. The vehicle speed signal is output from the control ECU (brake booster with master cylinder assembly) to the certification ECU (smart key ECU assembly) and then to the combination meter assembly. To create this signal, 12 V is output from terminal SI of the combination meter assembly to the certification ECU (smart key ECU assembly). The pulse signal is created by switching the transistor in the certification ECU (smart key ECU assembly) on and off, making the voltage on the wire drop to 0 V. A similar system is used for the output of this signal from the combination meter assembly via terminal +S. A voltage of 12 V or 5 V is applied to terminal +S from each ECU or relay that is connected to this terminal. The transistor in the combination meter assembly is controlled by the signal from the certification ECU (smart key ECU assembly). When this transistor is turned on, this transistor makes the voltage supplied by the various ECUs (via their respective internal resistors) drop to 0 V. Each ECU connected to terminal +S of the combination meter assembly controls its respective system based on this pulse signal.

HINT:

This circuit is used for the systems connected to terminal +S. This signal is not used for combination meter assembly operation. Combination meter assembly components such as the speedometer operate using data received via CAN communication. In addition, for some systems, vehicle speed information may be received via CAN communication.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

  • When replacing the combination meter assembly, always replace it with a new one. If a combination meter assembly which was installed to another vehicle is used, the information stored in it will not match the information from the vehicle and a DTC may be stored.
  • Before replacing the certification ECU (smart key ECU assembly), refer to Registration.

    Click here 2020 MY Corolla Corolla HV [01/2019 - 04/2020]; THEFT DETERRENT / KEYLESS ENTRY: SMART KEY SYSTEM (for Start Function, HV Model): REGISTRATION

PROCEDURE

1.

INSPECT COMBINATION METER ASSEMBLY (INPUT WAVEFORM)

*a

Component with harness connected

(Combination Meter Assembly)

*b

Waveform

(a) Check the signal waveform according to the condition(s) in the table below.

Item

Condition

Tester connection

I4-20 (SI) - Body ground

Tool setting

5 V/DIV., 20 ms./DIV.

Condition

Power switch on (IG), wheel being rotated

HINT:

When the system is functioning normally, one wheel revolution generates 4 pulses. As the vehicle speed increases, the width indicated by (A) in the illustration narrows.

Result

Proceed to

The measured waveform is similar to that in the illustration

A

The measured waveform is not similar to that in the illustration

(Stuck low)

B

The measured waveform is not similar to that in the illustration

(Stuck high)

C
B

GO TO STEP 6

C

GO TO STEP 9

A

2.

INSPECT COMBINATION METER ASSEMBLY (OUTPUT WAVEFORM)

*a

Component with harness connected

(Combination Meter Assembly)

*b

Waveform

(a) Check the signal waveform according to the condition(s) in the table below.

Item

Condition

Tester connection

I4-36 (+S) - Body ground

Tool setting

5 V/DIV., 20 ms./DIV.

Condition

Power switch on (IG), wheel being rotated

HINT:

  • When the system is functioning normally, one wheel revolution generates 4 pulses. As the vehicle speed increases, the width indicated by (A) in the illustration narrows.
  • The waveform (B) changes depending on the connected ECUs.

Result

Proceed to

The measured waveform is similar to that in the illustration

A

The measured waveform is not similar to that in the illustration

(Stuck low)

B

The measured waveform is not similar to that in the illustration

(Stuck high)

C
B

GO TO STEP 4

C

REPLACE COMBINATION METER ASSEMBLY 2020 MY Corolla Corolla Hatchback Corolla HV GR Corolla [01/2019 - 03/2019]; METER / GAUGE / DISPLAY: COMBINATION METER: REMOVAL 2020 - 2022 MY Corolla Corolla Hatchback Corolla HV GR Corolla [03/2019 - 09/2022]; METER / GAUGE / DISPLAY: COMBINATION METER: REMOVAL

A

3.

CHECK HARNESS AND CONNECTOR (EACH ECU - COMBINATION METER ASSEMBLY)

(a) Disconnect the A113 parking brake ECU (brake actuator assembly) connector.

(b) Disconnect the I55 radio and display receiver assembly connector.

(c) Disconnect the I72 DCM (telematics transceiver) connector.*

(d) Disconnect the I4 combination meter assembly connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

A113-27 (SPD) - I4-36 (+S)

Always

Below 1 Ω

I55-27 (SPD) - I4-36 (+S)

Always

Below 1 Ω

I72-10 (SPDP) - I4-36 (+S)*

Always

Below 1 Ω
  • *: w/ Manual (SOS) Switch
OK

CHECK THE VOLTAGE AT TERMINAL SPD OR SPDP OF EACH ECU
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

4.

INSPECT EACH ECU (INTERNAL SHORT)

*a

Component with harness connected

(Combination Meter Assembly)

(a) Disconnect one of the connectors below.

NOTICE:

After disconnecting a connector, perform all steps with all other ECUs connected.

Terminal No. (Symbol)

ECU

A113

Parking brake ECU (brake actuator assembly)

I55

Radio and display receiver assembly

I72*

DCM (telematics transceiver)
  • *: w/ Manual (SOS) Switch

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

NOTICE:

Make sure to perform this inspection with the wheels stopped.

Standard Voltage:

Tester Connection

Condition

Specified Condition

I4-36 (+S) - Body ground

Power switch on (IG)

4.5 to 14 V

(c) Repeat steps (a) and (b) for each connected ECU.

HINT:

If the voltage changed to the specified voltage after disconnecting a connector, an internal short in the disconnected ECU is suspected.

Result

Proceed to

After performing the inspection procedure for all connectors, the voltage did not change to the specified voltage

A

When disconnecting the connector of the parking brake ECU (brake actuator assembly), the voltage changed to the specified voltage

B

When disconnecting the connector of the radio and display receiver assembly, the voltage changed to the specified voltage

C

When disconnecting the connector of the DCM (telematics transceiver), the voltage changed to the specified voltage

(w/ Manual (SOS) Switch)

D
B

REPLACE PARKING BRAKE ECU (BRAKE ACTUATOR ASSEMBLY)

C

REPLACE RADIO AND DISPLAY RECEIVER ASSEMBLY 2020 MY Corolla Corolla Hatchback Corolla HV GR Corolla [01/2019 - 03/2019]; AUDIO / VIDEO: RADIO RECEIVER: REMOVAL 2020 - 2022 MY Corolla Corolla Hatchback Corolla HV GR Corolla [03/2019 - 09/2022]; AUDIO / VIDEO: RADIO RECEIVER: REMOVAL

D

REPLACE DCM (TELEMATICS TRANSCEIVER) 2020 MY Corolla Corolla Hatchback Corolla HV GR Corolla [01/2019 - 09/2019]; CELLULAR COMMUNICATION: DCM(TELEMATICS TRANSCEIVER): REMOVAL 2020 MY Corolla Corolla Hatchback Corolla HV GR Corolla [09/2019 - 04/2020]; CELLULAR COMMUNICATION: DCM(TELEMATICS TRANSCEIVER): REMOVAL

A

5.

CHECK HARNESS AND CONNECTOR (EACH ECU - COMBINATION METER ASSEMBLY)

(a) Disconnect the A113 parking brake ECU (brake actuator assembly) connector.

(b) Disconnect the I55 radio and display receiver assembly connector.

(c) Disconnect the I72 DCM (telematics transceiver) connector.*

(d) Disconnect the I4 combination meter assembly connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

A113-27 (SPD), I55-27 (SPD) or I72-10 (SPDP)* - I4-36 (+S)

Always

Below 1 Ω

A113-27 (SPD), I55-27 (SPD), I72-10 (SPDP)* or I4-36 (+S) - Body ground

Always

10 kΩ or higher
  • *: w/ Manual (SOS) Switch
OK

REPLACE COMBINATION METER ASSEMBLY 2020 MY Corolla Corolla Hatchback Corolla HV GR Corolla [01/2019 - 03/2019]; METER / GAUGE / DISPLAY: COMBINATION METER: REMOVAL 2020 - 2022 MY Corolla Corolla Hatchback Corolla HV GR Corolla [03/2019 - 09/2022]; METER / GAUGE / DISPLAY: COMBINATION METER: REMOVAL

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

6.

CHECK FOR DTC (SMART KEY SYSTEM (FOR START FUNCTION))

(a) Check if smart key system (for start function) DTCs are output.

Body Electrical > Power Source Control > Trouble Codes

Result

Proceed to

DTCs are not output

A

DTCs are output

B
B

GO TO SMART KEY SYSTEM (FOR START FUNCTION)

A

7.

INSPECT COMBINATION METER ASSEMBLY

HINT:

This procedure is performed to check the diode inside the combination meter assembly.

(a) Remove the combination meter assembly.

Click here 2020 MY Corolla Corolla Hatchback Corolla HV GR Corolla [01/2019 - 03/2019]; METER / GAUGE / DISPLAY: COMBINATION METER: REMOVAL 2020 - 2022 MY Corolla Corolla Hatchback Corolla HV GR Corolla [03/2019 - 09/2022]; METER / GAUGE / DISPLAY: COMBINATION METER: REMOVAL

(b) Measure the internal resistance of the combination meter assembly.

Standard Resistance:

Tester Connection

Tester Connection

Condition

Measured Value

I4-38 (IG+) - I4-20 (SI)
  • Positive (+) tester probe → I4-38 (IG+)
  • Negative (-) tester probe → I4-20 (SI)

Always

A

I4-38 (IG+) - I4-20 (SI)
  • Positive (+) tester probe → I4-20 (SI)
  • Negative (-) tester probe → I4-38 (IG+)

Always

B

OK:

There is a large difference between the measured value (A) and the measured value (B).

NG

REPLACE COMBINATION METER ASSEMBLY 2020 MY Corolla Corolla Hatchback Corolla HV GR Corolla [01/2019 - 03/2019]; METER / GAUGE / DISPLAY: COMBINATION METER: REMOVAL 2020 - 2022 MY Corolla Corolla Hatchback Corolla HV GR Corolla [03/2019 - 09/2022]; METER / GAUGE / DISPLAY: COMBINATION METER: REMOVAL

OK

8.

CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) - COMBINATION METER ASSEMBLY)

(a) Disconnect the I1 certification ECU (smart key ECU assembly) connector.

(b) Disconnect the I4 combination meter assembly connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

I1-21 (SPDO) or I4-20 (SI) - Body ground

Always

10 kΩ or higher
OK

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) 2020 MY Corolla Corolla Hatchback Corolla HV GR Corolla [01/2019 - 03/2019]; THEFT DETERRENT / KEYLESS ENTRY: CERTIFICATION ECU: REMOVAL 2020 - 2022 MY Corolla Corolla Hatchback Corolla HV GR Corolla [03/2019 - 09/2022]; THEFT DETERRENT / KEYLESS ENTRY: CERTIFICATION ECU: REMOVAL

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

9.

CHECK FOR DTC (SMART KEY SYSTEM (FOR START FUNCTION))

(a) Check if smart key system (for start function) DTCs are output.

Body Electrical > Power Source Control > Trouble Codes

Result

Proceed to

DTCs are not output

A

DTCs are output

B
B

GO TO SMART KEY SYSTEM (FOR START FUNCTION)

A

10.

CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) - COMBINATION METER ASSEMBLY)

(a) Disconnect the I1 certification ECU (smart key ECU assembly) connector.

(b) Disconnect the I4 combination meter assembly connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

I1-21 (SPDO) - I4-20 (SI)

Always

Below 1 Ω
OK

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) 2020 MY Corolla Corolla Hatchback Corolla HV GR Corolla [01/2019 - 03/2019]; THEFT DETERRENT / KEYLESS ENTRY: CERTIFICATION ECU: REMOVAL 2020 - 2022 MY Corolla Corolla Hatchback Corolla HV GR Corolla [03/2019 - 09/2022]; THEFT DETERRENT / KEYLESS ENTRY: CERTIFICATION ECU: REMOVAL

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR