Inter-Axle Differential Lock Control Valve Diagnosis

Inter-Axle Differential Lock Control Valve Diagnosis

1. Block the wheels.
2. Apply the parking brake.
3. Drain all of the air reservoirs. Refer to Draining Reservoirs .
4. Remove the air line from the inter-axle differential lock control valve delivery port.
5. Install an air pressure gauge into the delivery port of the inter-axle differential lock control valve.
6. Shift the inter-axle differential lock control valve lever to OFF.
7. Start the engine. Charge the air system to the air compressor governor cutout point.
8. Stop the engine.
9. Shift the inter-axle differential lock control valve lever to ON.
10. Verify that the air pressure reading on the air gauge is comparable with the vehicle's air pressure gauge. If the readings on the gauges are not comparable, repair or replace the inter-axle differential lock control valve.
11. Drain all of the air reservoirs.
12. Remove the air pressure gauge from the delivery port of the inter-axle differential lock control valve.
13. Install the air line into the inter-axle differential lock control valve delivery port.
14. Start the engine. Charge the air system to the air compressor governor cutout point.
15. Stop the engine.
16. Inspect for air leaks using a soap solution. Air leakage is not allowed. If any air leaks are present, repair or replace parts as needed.