Lexus RX (RX 350L, RX450h) 2016-2022 Repair Manual: Starter Relay Circuit Short to Battery (P061512)

DESCRIPTION

While the engine is being cranked, battery voltage is applied to terminal STA of the ECM.

If the ECM detects the starter control (STA) signal while the vehicle is being driven, it determines that there is a malfunction in the STA circuit. The ECM then illuminates the MIL and stores this DTC.

This monitor runs when the vehicle is driven at 20 km/h (12 mph) or more for 20 seconds or more.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

MIL

Memory

Note

P061512

Starter Relay Circuit Short to Battery

1. Diagnosis Condition 2. Malfunction Status 3. Malfunction Time 4. Other

  • Battery voltage of 10.5 V or more applied to the ECM
  • When conditions (a), (b) and (c) are met.
    1. Vehicle speed of 20 km/h (12 mph) or more
    2. Engine speed of more than 1000 rpm
    3. STA signal ON
  • 20 seconds or more
  • 1-trip detection logic
  • Park/neutral position switch assembly
  • Starter relay circuit
  • Cranking holding function circuit
  • Harness and connector
  • ECM
  • Certification ECU (Smart key ECU assembly)
  • Engine stop and start ECU

Comes on

DTC stored

SAE Code:

P0617

MONITOR STRATEGY

Related DTCs

P0617: Starter signal

Required Sensors/Components (Main)

ST relay, Park/neutral position switch assembly, Certification ECU (Smart Key ECU Assembly)

Required Sensors/Components (Sub)

Vehicle speed sensor (VSS), Crankshaft position (CKP) sensor

Frequency of operation

Continuous

Duration

20 sec.

MIL operation

Immediate

Sequence of operation

None

TYPICAL ENABLING CONDITIONS

The monitor will run whenever the following DTCs are not present

None

Battery voltage

10.5 V or more

Vehicle speed

20 km/h (12.43 mph) or more

Engine speed

1000 rpm or more

TYPICAL MALFUNCTION THRESHOLDS

Starter signal

ON

CONFIRMATION DRIVING PATTERN

CAUTION:

When performing the confirmation driving pattern, obey all speed limits and traffic laws.

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. Start the engine.
  7. Drive the vehicle for 20 seconds or more with the following conditions met [*1]:
    • Engine speed is 1000 rpm or more.
    • Vehicle speed is 20 km/h (12 mph) or more.

      HINT:

      [*1] : Normal judgment procedure.

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

  8. Stop the vehicle.
  9. Enter the following menus: Powertrain / Transmission / Utility / All Readiness.
  10. Input the DTC: P061512.
  11. 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.

WIRING DIAGRAM

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

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

PROCEDURE

1.

READ VALUE USING TECHSTREAM (STARTER 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 / Transmission / Data List / Starter SW.

Powertrain > Transmission > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

Starter SW

Starter signal

OFF or ON

  • ON: Starter operating
  • OFF: Starter not operating

-

Powertrain > Transmission > Data List

Tester Display

Starter SW

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

Standard:

Condition

Starter SW

Engine switch on (IG)

OFF

(f) Read the Data List according to the display on the Techstream while the vehicle is being driven with an engine speed of 1000 rpm or more at a vehicle speed of 20 km/h (12 mph) or more.

Standard:

Condition

Starter SW

Driving at 20 km/h (12 mph) or more (engine speed 1000 rpm or more)

OFF

HINT:

If the result of either of the above is not as specified, proceed to the next step with the engine switch on (IG), Techstream connected and Data List item "Starter SW" selected.

HINT:

If the starter assembly operates continuously when the engine switch is turned on (IG), proceed to the next step without reading the Data List item "Starter SW".

OK

SYMPTOMS SIMULATION AND DTC CHECK

NG

2.

INSPECT ST RELAY (CHECK FOR SHORT CIRCUIT)

(a) Enter the following menus: Powertrain / Transmission / Data List / Starter SW.

Powertrain > Transmission > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

Starter SW

Starter signal

OFF or ON

  • ON: Starter operating
  • OFF: Starter not operating

-

Powertrain > Transmission > Data List

Tester Display

Starter SW

(b) Remove the ST relay from the engine room relay block and junction block assembly.

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

Result

Proceed to

The Data List item "Starter SW" does not change from ON.

A

The Data List item "Starter SW" changes from ON to OFF.

B

HINT:

  • When the result of the above inspection is "The Data List item "Starter SW" does not change from ON", the ST relay is normal.
  • DTCs may be stored during this inspection. Check for DTCs and clear them using the Techstream.
B

REPLACE ST RELAY

A

3.

CHECK TERMINAL VOLTAGE (POWER SOURCE OF ST RELAY)

HINT:

The purpose of this step is to check for ST relay terminal voltage under abnormal conditions.

(a) Remove the ST relay from the engine room relay block and junction block assembly.

*1

Engine Room Relay Block and Junction Block Assembly

*2

ST Relay

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

(c) Measure the voltage between ST relay terminal 2 and body ground.

HINT:

  • Make a note of the measured voltage as it will be necessary for inspecting the change in voltage in the next step. As the next step should be conducted under the same conditions, keep the engine switch on (IG) and do not install the ST relay.
  • DTCs may be stored during this inspection. Check for DTCs and clear them using the Techstream.
  • If any voltage was measured with the engine switch on (IG), one of the following malfunctions is suspected:
    • Short to +B in the circuit of a connected ECU or park/neutral position switch assembly.
    • Short to +B in the wire harness.
NEXT

4.

INSPECT PARK/NEUTRAL POSITION SWITCH ASSEMBLY (CHECK FOR SHORT CIRCUIT)

(a) Disconnect the D15 park/neutral position switch assembly connector.

*1

Engine Room Relay Block and Junction Block Assembly

*2

ST Relay

(b) Measure the voltage between ST relay terminal 2 and body ground and compare it to the voltage measured in the previous step.

Result

Proceed to

The voltage between ST relay terminal 2 and body ground does not change when the connector is disconnected.

A

The voltage between ST relay terminal 2 and body ground changes when the connector is disconnected.

B

HINT:

  • If the voltage is the same before and after disconnecting the connector, the park/neutral position switch assembly is normal.
  • DTCs may be stored during this inspection. Check for DTCs and clear them using the Techstream.
B

REPLACE PARK/NEUTRAL POSITION SWITCH ASSEMBLY

A

5.

INSPECT ECM (CHECK FOR SHORT CIRCUIT)

(a) Disconnect the A37 ECM connector.

*1

Engine Room Relay Block and Junction Block Assembly

*2

ST Relay

(b) Measure the voltage between ST relay terminal 2 and body ground and compare it to the voltage measured in the previous step.

Result

Proceed to

The voltage between ST relay terminal 2 and body ground does not change when the connector is disconnected.

A

The voltage between ST relay terminal 2 and body ground changes when the connector is disconnected.

B

HINT:

  • If the voltage is the same before and after disconnecting the connector, the ECM is normal.
  • DTCs may be stored during this inspection. Check for DTCs and clear them using the Techstream.
B

GO TO STEP 7

A

6.

CHECK HARNESS AND CONNECTOR (ECM - PARK/NEUTRAL POSITION SWITCH ASSEMBLY - SMART KEY ECU ASSEMBLY - ST RELAY)

(a) Disconnect the A37 ECM connector.

(b) Disconnect the D15 park/neutral position switch assembly connector.

(c) Disconnect the A74 certification ECU (smart key ECU assembly) connector.

(d) Remove the ST relay from the engine room relay block and junction block assembly.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

A37-43 (STA), D15-9 (L), A74-20 (STA) or 2 (ST relay) - Other terminals

Always

10 kΩ or higher

OK

CHECK SMART ACCESS SYSTEM WITH PUSH-BUTTON START (CHECK FOR STA TERMINAL VOLTAGE OF SMART KEY ECU ASSEMBLY)

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

7.

REPLACE ECM

(a) Replace the ECM.

Click here

NEXT

PERFORM A/T CODE REGISTRATION

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