ELC System Leak Test

When diagnostic procedures require that vehicle be raised on a hoist, it is important that the rear axle assembly remains in the normal trim height position at all times. When a frame contact hoist is used, two additional jack stands should be used to support the rear axle or control arms in the normal trim height position.

Fig. 22 Compressor Leak Test:

1. Tee pressure gauge tool No. J 22124-A into ELC system between dryer assembly and pressure regulator valve. Install so that shut-off valve is on the compressor side of gauge.
2. With shutoff valve open, apply service air pressure through service valve on gauge until gauge reads 100 psi.
3. If leak is indicated, close shutoff valve and continue to observe for pressure drop. Closing valve isolates the compressor from the rest of the system.
4. If gauge pressure continues to drop, leak is external to the compressor. Leak test all connections with soap and water or suitable leak test solution.
5. If gauge pressure does not continue to drop, leak is in the compressor. Refer to Fig. 22 to check compressor for leaks.
6. If pressure builds up rapidly but vehicle does not raise, check for pinched air lines and stuck or binding shocks.