Lexus NX: IG Power Supply Voltage (C1551)

DESCRIPTION

The power steering ECU assembly distinguishes the power switch status as on (IG) or off through the IG power source circuit.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

Warning Indicate

Return-to-normal Condition

C1551

IG Power Supply Voltage

IG power source circuit malfunction inside ECU

  • EPS-IG fuse
  • IG power source circuit
  • ECU wire sub-assembly
  • Power steering ECU assembly

On

After normal confirmation

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

If the power steering ECU assembly has been replaced, perform assist map writing.

Click here

HINT:

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

PROCEDURE

1.

CHECK CONNECTOR CONNECTION CONDITION AND GROUND WIRE

(a) Check the connection condition of the ECU wire sub-assembly and power steering ECU assembly connectors.

OK:

The ECU wire sub-assembly and power steering ECU assembly connectors are securely connected.

(b) Check that the ground wire is securely installed with the bolt.

Click here

OK:

The ground wire is securely installed with the bolt.

NG

CONNECT CONNECTOR OR INSTALL GROUND WIRE

OK

2.

READ VALUE USING TECHSTREAM (IG POWER SUPPLY)

(a) Turn the power switch off.

(b) Connect the Techstream to the DLC3.

(c) Turn the power switch on (IG).

(d) Turn the Techstream on.

(e) Enter the following menus: Chassis / EMPS / Data List.

(f) Select the item "IG power supply" in the Data List and read the value displayed on the Techstream.

Chassis > EMPS > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

IG Power Supply

ECU power source voltage

Min.: 0.0000 V

Max.: 20.1531 V

Power switch on (IG): 8 to 16 V

-

Chassis > EMPS > Data List

Tester Display

IG Power Supply

OK:

The normal condition value is displayed on the Techstream.

OK

CHECK INTERMITTENT PROBLEMS

NG

3.

CHECK HARNESS AND CONNECTOR (IG POWER SUPPLY)

(a) Disconnect the nl1 ECU wire sub-assembly connector.

*a

Front view of wire harness connector

(to ECU Wire Sub-assembly)

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

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

Standard Voltage:

Tester Connection

Switch Condition

Specified Condition

nl1-5 (IG) - Body ground

Power switch on (IG)

8 to 16 V

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

4.

CHECK ECU WIRE SUB-ASSEMBLY

(a) Connect the nl1 connector to the ECU wire sub-assembly.

*a

Front view of wire harness connector

(to Power Steering ECU Assembly)

(b) Disconnect the n3 and n1 power steering ECU assembly connectors.

(c) Turn the power switch on (IG).

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

Standard Voltage:

Tester Connection

Switch Condition

Specified Condition

n3-1 (IG) - Body ground

Power switch on (IG)

8 to 16 V

(e) Turn the power switch off.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

n1-2 (PGND) - Body ground

Always

Below 1 Ω

OK

REPLACE POWER STEERING ECU ASSEMBLY

NG

REPAIR OR REPLACE ECU WIRE SUB-ASSEMBLY

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