Speed Signal Circuit [04/2020 - 09/2022]: Procedure

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. 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

   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

Result: 

B 

See step  6

Result: 

C 

See step  9

Result: 

A 

See step  2

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. 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

   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

Result: 

B 

See step  4

Result: 

C 

REPLACE COMBINATION METER ASSEMBLY 

Refer to REMOVAL [03/2019 - 09/2022]

Result: 

A 

See step  3

1. Disconnect the A113 parking brake ECU (brake actuator assembly) connector.
2. Disconnect the I55 radio and display receiver assembly connector.
3. Disconnect the I4 combination meter assembly connector.
4. 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

   Result

   Proceed to
   OK
   NG

Result: 

OK 

CHECK THE VOLTAGE AT TERMINAL SPD OF EACH ECU 

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. Disconnect one of the connectors below.
   NOTE:

   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

2. Measure the voltage according to the value(s) in the table below.
   NOTE:

   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

3. 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

   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

Result: 

B 

REPLACE PARKING BRAKE ECU (BRAKE ACTUATOR ASSEMBLY) 

Refer to REMOVAL [01/2019 - 09/2022]

Result: 

C 

REPLACE RADIO AND DISPLAY RECEIVER ASSEMBLY 

Refer to REMOVAL [03/2019 - 09/2022]

Result: 

A 

See step  5

1. Disconnect the A113 parking brake ECU (brake actuator assembly) connector.
2. Disconnect the I55 radio and display receiver assembly connector.
3. Disconnect the I4 combination meter assembly connector.
4. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   A113-27 (SPD) or I55-27 (SPD) - I4-36 (+S)	Always	Below 1 Ω
   A113-27 (SPD), I55-27 (SPD) or I4-36 (+S) - Body ground	Always	10 kΩ or higher

   Result

   Proceed to
   OK
   NG

Result: 

OK 

REPLACE COMBINATION METER ASSEMBLY 

Refer to REMOVAL [03/2019 - 09/2022]

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

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

   Body Electrical > Power Source Control > Trouble Codes 

   Result

   Result	Proceed to
   DTCs are not output	A
   DTCs are output	B

Result: 

B 

GO TO SMART KEY SYSTEM (FOR START FUNCTION) 

Refer to DIAGNOSTIC TROUBLE CODE CHART [04/2020 - 09/2022]

Result: 

A 

See step  7

HINT: 

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

1. Remove the combination meter assembly.

   Refer to REMOVAL [03/2019 - 09/2022]

2. 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).

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPLACE COMBINATION METER ASSEMBLY 

Refer to REMOVAL [03/2019 - 09/2022]

Result: 

OK 

See step  8

1. Disconnect the I1 certification ECU (smart key ECU assembly) connector.
2. Disconnect the I4 combination meter assembly connector.
3. 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

   Result

   Proceed to
   OK
   NG

Result: 

OK 

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) 

Refer to REMOVAL [03/2019 - 09/2022]

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

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

   Body Electrical > Power Source Control > Trouble Codes 

   Result

   Result	Proceed to
   DTCs are not output	A
   DTCs are output	B

Result: 

B 

GO TO SMART KEY SYSTEM (FOR START FUNCTION) 

Refer to DIAGNOSTIC TROUBLE CODE CHART [04/2020 - 09/2022]

Result: 

A 

See step  10

1. Disconnect the I1 certification ECU (smart key ECU assembly) connector.
2. Disconnect the I4 combination meter assembly connector.
3. 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

   Result

   Proceed to
   OK
   NG

Result: 

OK 

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) 

Refer to REMOVAL [03/2019 - 09/2022]

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR