Air Suspension System

SUSPENSION CONTROL: AIR SUSPENSION SYSTEM: C1741/41: Air Suspension Relay Circuit

DTC C1741/41 - Air Suspension Relay Circuit

DESCRIPTION

When the "UP" side of the height control switch is pressed, a signal is sent from terminal RC of the suspension control ECU to the AIR SUS relay to turn it on.
As a result, the current flows to the AIR SUS relay coil, closing the relay contact, and then the battery positive voltage is applied to the compressor, which causes the compressed air to raise the vehicle height.





HINT: Once the ECU stores DTC C1741/41 in the memory, the vehicle height control is suspended until a normal signal is input to the ECU from the AIR SUS relay. However, the control resumes if the ignition switch is turned OFF, and then turned ON again.

WIRING DIAGRAM





INSPECTION PROCEDURE
HINT:
- If DTC C1761/61 (ECU malfunction) and/or C1774/74 (power source circuit) is displayed, perform the inspection necessary for DTC C1761/61 Air Suspension System and/or C1774/74 Air Suspension System first.
(If DTC C1761/61 and C1774/74 are output at the same time, perform the inspection necessary for DTC C1774/74 first.)
- Start the inspection from step 1 when using the Techstream, and start from step 2 when not using the Techstream.

PROCEDURE

1. PERFORM ACTIVE TEST USING TECHSTREAM
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch ON and the Techstream on.
(c) Select the item "Motor Relay" in the Active Test, and operate it with the Techstream.
(d) Check the operating sound of the AIR SUS relay when operating it with the Techstream.
OK:
The operating sound of the AIR SUS relay can be heard.
OK -- REPLACE SUSPENSION CONTROL ECU
NG -- Continue to next step.
2. INSPECT AIR SUS RELAY





(a) Remove the AIR SUS relay from the engine room R/B No. 3.
(b) Measure the resistance between each terminal of the AIR SUS relay.
Standard resistance:






NG -- REPLACE AIR SUS RELAY
OK -- Continue to next step.
3. CHECK HARNESS AND CONNECTOR (ENGINE ROOM R/B - SUSPENSION CONTROL ECU)
(a) Check for an open or short circuit in the harness and the connector between the AIR SUS relay and the suspension control ECU Electronic Circuit Inspection Procedure.
OK:
There is no open or short in the wire harness.
(b) Check for an open circuit in the harness and the connector between the AIR SUS relay and the body ground.
OK:
There is no open in the wire harness.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE SUSPENSION CONTROL ECU