System Diagnostics

Fig. 9 Residual air check:

Fig. 10 Automatic Load Leveling System:

NOTE: Cycle ignition switch, "Off" and "On" during testing. If during testing the vehicle is allowed to remain in a low or high position for more than 3.5 minutes with ignition "On," then the height sensor time limit function must be reset as described above.

1. With manual switch in "ACC" position, observe if compressor is operating.

a. If compressor is not operating, check wire connections at compressor motor terminals. Probe red wire at compressor motor terminal with a test lamp connected to ground. If test lamp lights, proceed to step 3, if not, step 2.
b. If compressor is operating, but vehicle remains low, proceed to step 8.
c. If system is operating properly, move manual switch to "Auto" mode and proceed to step 6.

2. Check fusible link.

a. If fusible link is blown, temporarily replace it with a circuit breaker and recheck operation. If system operates satisfactorily, install new fusible link and proceed to step 3.
b. If fusible link is satisfactory, proceed to step 4.

3. Disconnect red wire from compressor motor terminal and connect a jumper wire from battery to compressor motor terminal through an ammeter. Compressor current draw should not exceed 14.0 amps.

a. If current draw is satisfactory, proceed to step 4.
b. If compressor is not operating or current draw exceeds 14.0 amps, check for shorted or grounded condition in compressor motor. Replace if necessary.

4. Turn ignition "On," and connect test lamp to ground. With manual switch in "ACC" position probe red wire with tracer in manual switch connector.

a. If test lamp lights, probe red wire with tracer at compressor motor terminal. If test lamp lights, replace compressor. If not, repair open circuit between manual switch and compressor, and proceed to step 5.
b. If test lamp does not light, replace manual switch.

5. With ignition "On," and manual switch in the "Auto" position, connect a jumper wire from compressor relay violet wire terminal to ground.

a. If compressor operates, proceed to step 6.
b. If compressor does not operate, connect a test lamp to ground and probe compressor relay red wire terminals. If test lamp lights, probe compressor relay red with tracer wire terminal. If test lamp lights, repair open circuit in compressor relay wiring to compressor motor terminal. If test lamp does not light, check for open circuit between compressor relay and fusible link. If satisfactory, replace relay.

6. Cycle ignition switch "Off" and "On." Leave ignition "On." Raise and support rear of vehicle, then check to ensure that wiring to sensor is properly connected. Also check to ensure that the link is attached to the height sensor arm and that the sensor arm adjusting nut is tight.

a. If all items are found to be satisfactory, proceed to step 7.
b. If any of the above items are found to be defective, repair as necessary.

7. With ignition "On" disconnect electrical connector from height sensor, connect a test lamp lead to ground and probe terminals 5 and 6 of the height sensor electrical connector. Test lamp should light at both terminals.

a. If test lamp lights at both terminals, proceed to step 9.
b. If test lamp lights at terminal 5 only, locate and repair open circuit to No. 6 height sensor terminal.
c. If test lamp lights at terminal 6 only, locate and repair open circuit to No. 5 height sensor terminal.

8. With ignition "On," connect a jumper wire from terminal 3 of the height sensor electrical connector to ground. Then connect jumper wire from terminal 3 to terminal 4 of the height sensor connector.

a. Compressor does not operate with jumper wire connected from terminal 3 to ground. Repair open in wire to terminal 3 of the connector.
b. Compressor operates with jumper from terminal 3 to ground but inoperative with jumper wire from terminal 3 to terminal 4. Repair open in height sensor ground circuit.
c. Compressor operates satisfactory with jumper wire in either position. Reconnect electrical connector to height sensor and perform height sensor operational check. Replace or adjust height sensor as necessary.

9. Attach pressure gauge as shown and be sure gauge shut-off valve is in "Off" position. Inflate system through pressure gauge fill valve to 80 to 100 psi and observe if vehicle raises and pressure remains steady for approximately 10 minutes. If system fails to inflate to 80 - 100 psi, a severe leak is indicated between gauge and shock absorbers.

a. If vehicle raises and pressure holds steady, proceed to step 10.
b. If vehicle raises but pressure leaks down, locate and repair leak in pressure lines, fittings or shock absorbers.
c. If vehicle does not raise but pressure increases to 80 - 100 psi, check for pinched pressure line between compressor and shock absorbers.

10. Disconnect wire connector from compressor solenoid valve terminals and open pressure gauge shut-off valve. Inflate system through service valve to 80 - 100 psi, then observe if pressure leaks down.

a. If pressure holds steady, deflate system and reconnect electrical connectors.
b. If pressure leaks down, perform compressor leak down test and repair or replace as necessary.

11. With ignition "On," raise and support rear of vehicle. Check height sensor operation.

a. Shocks inflate. Check system operation.
b. Shocks do not inflate. Go to step 12.

12. With ignition "On," disconnect electrical connector from height sensor and connect a jumper wire from terminal 3 to terminal 4 of the connector. Observe if shocks inflate and car raises.

a. If shocks inflate and car raises, replace height sensor and check operation before lowering car.
b. If shocks do not inflate, check for grounded condition in wires between sensor and compressor solenoid valve.