ECU Power Source Circuit

SUSPENSION CONTROL: AIR SUSPENSION SYSTEM: ECU Power Source Circuit
- ECU Power Source Circuit

DESCRIPTION

When the engine switch is on (IG), the driver side junction block AIR SUS relay turns ON, and power is supplied to the suspension control ECU.

WIRING DIAGRAM





INSPECTION PROCEDURE

NOTICE:
* Before performing troubleshooting, inspect the connectors of related circuits.
* Before replacing the suspension control ECU, perform all of the following again: 1) symptom simulation Electronic Circuit Inspection Procedure; 2) DTC inspection; and 3) Techstream inspection (Data List or Active Test). If no malfunctions are found in other areas, replace the suspension control ECU.
* If the suspension control ECU or height control sensor is replaced, the vehicle height offset calibration must be performed Programming and Relearning.

PROCEDURE

1. CHECK IG VOLTAGE (DATA LIST)

(a) Turn the engine switch off.

(b) Connect the Techstream to the DLC3.

(c) Turn the engine switch on (IG) and the Techstream on.

(d) Enter the following menus: Chassis / Air suspension / Data List.

(e) Check the values by referring to the table below.

Air suspension





OK:

11 to 14 V

Result





B -- PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE Symptom Related Diagnostic Procedures
A -- Continue to next step.

2. INSPECT FUSE (AIR SUS)

(a) Remove the AIR SUS fuse from the passenger side junction block.

(b) Measure the resistance of the fuse.

Standard resistance:





NG -- CHECK HARNESS AND CONNECTOR (PASSENGER SIDE JUNCTION BLOCK - ECU)
OK -- Continue to next step.

3. INSPECT PASSENGER SIDE JUNCTION BLOCK (AIR SUS RELAY)

(a) Disconnect the L88 ECU connector.





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

Standard voltage:





Result





B -- REPLACE SUSPENSION CONTROL ECU Removal
A -- Continue to next step.

4. CHECK HARNESS AND CONNECTOR (PASSENGER SIDE JUNCTION BLOCK - ECU AND BODY GROUND)

(a) Disconnect the L88 ECU connector.

(b) Disconnect the PA passenger side junction block connector.

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

Standard resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

5. CHECK HARNESS AND CONNECTOR (BATTERY - PASSENGER SIDE JUNCTION BLOCK)

(a) Disconnect the PL junction block connector.

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





Standard voltage:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

6. CHECK HARNESS AND CONNECTOR (MAIN BODY ECU - JUNCTION BLOCK AND BODY GROUND)

(a) Disconnect the PA junction block connector.

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





Standard voltage:





Standard resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

7. CHECK HARNESS AND CONNECTOR (PASSENGER SIDE JUNCTION BLOCK - ECU)

(a) Disconnect the L88 ECU connector.

(b) Connect the PA passenger side junction block connector.





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

Standard resistance:





HINT
If the fuse is blown, replace the fuse.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPLACE PASSENGER SIDE JUNCTION BLOCK