C1774

SUSPENSION CONTROL: AIR SUSPENSION SYSTEM: C1774/74: Power Source Circuit

DTC C1774/74 - Power Source Circuit

DESCRIPTION

When turning the ignition switch to the ON position, the battery positive voltage is input to terminal B and IG of the suspension control ECU. By turning the ignition switch to OFF, the supply of the battery positive voltage to terminal B and IG terminals stops, and the power is turned OFF.





WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

1. INSPECT SOURCE VOLTAGE
(a) Check the battery voltage.
Standard voltage:
11 to 14 V

HINT: Start the inspection from step 2 when using the Techstream, and start from step 3 when not using the Techstream.

NG -- REPLACE BATTERY
OK -- Continue to next step.

2. INSPECT FUSE (AIR SUS NO.2)




(a) Remove the AIR SUS No. 2 fuse from the engine room R/B.
(b) Measure the resistance of the AIR SUS No. 2 fuse.
Standard resistance:
Below 1 Ohms

NG -- REPLACE FUSE
OK -- Continue to next step.

3. INSPECT FUSE (ECU-IG)




(a) Remove the ECU-IG fuse from the driver side J/B.
(b) Measure the resistance of the ECU-IG fuse.
Standard resistance:
Below 1 Ohms

NG -- REPLACE FUSE
OK -- Continue to next step.

4. INSPECT SUSPENSION CONTROL ECU




(a) Remove the suspension control ECU with connectors still connected.
(b) Turn the ignition switch ON, and measure voltage between terminal S14-6 (B) and S15-1 (GND) and between terminal S14-6 (B) and S14-5 (GND2) of the suspension control ECU connector.
Standard voltage:
10 to 14 V




(c) Turn the ignition switch ON, measure voltage between terminals S15-10 (IG) and S15-1 (GND) and between terminals S15-10 (IG) and S14-5 (GND2) of the suspension control ECU connector.
Standard voltage:
10 to 14 V
OK -- REPLACE SUSPENSION CONTROL ECU

NG -- Continue to next step.

5. CHECK HARNESS AND CONNECTOR (SUSPENSION CONTROL ECU - BODY GROUND)




(a) Disconnect the suspension control ECU connectors.
(b) Turn the ignition switch ON and measure the resistance between terminal S15-1 (GND) and body ground and between terminal S14-5 (GND2) and body ground.
Standard resistance:
Below 1 Ohms

HINT:
- OK:
Repair or replace the harness or the connector between the AIR SUS fuse and the suspension control ECU and/or the ECU-IG fuse and the suspension control ECU.
-
NG:
Repair or replace the harness or the connector between the suspension control ECU and body ground.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE SUSPENSION CONTROL ECU