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Test H (Code 54) Unable To Detect Rear Raising

  1. Enter Super Star II tester Functional Test Code 31 (compressor relay toggle). See FUNCTIONAL TEST under TESTING & DIAGNOSIS. Turn air suspension switch to ON position. Compressor should cycle on and off repeatedly during test. If compressor cycles, go to step 9). If compressor does not cycle, DO NOT exit Functional Test Code 31. Go to next step.
  2. Remove air cleaner assembly and compressor shield. Disconnect compressor electrical connector. Measure voltage between circuit No. 578 (Light Blue/Pink wire) and circuit No. 57 (Black wire) of compressor harness connector. Voltmeter should pulse between zero volts and battery voltage. If voltmeter pulses, connect compressor connector. Wait 10 minutes for compressor internal circuit breaker to cool down and close. If compressor does not start to cycle after 10 minutes, replace compressor. Repeat SERVICE BAY DIAGNOSTICS under TESTING & DIAGNOSIS. If voltmeter reads zero volts, DO NOT exit Functional Test Code 31. Go to next step.
  3. Compressor relay should cycle on and off during this test. If relay cycles, exit Functional Test Code 31 and go to step 7). If relay does not cycle, exit Functional Test Code 31 and go to next step.
  4. Remove compressor relay and install horn relay in its place. See TEST A (CODE 39), COMPRESSOR RELAY CIRCUIT. Repeat SERVICE BAY DIAGNOSTICS under TESTING & DIAGNOSIS in this article. If Code 54 is displayed, install relays in original positions and go to next step. If Code 54 is not displayed, install horn relay in original position. Replace compressor relay. Repeat SERVICE BAY DIAGNOSTICS under TESTING & DIAGNOSIS.
  5. Measure voltage between circuit No. 414 (Orange/Red wire) at relay terminal and ground. See Fig 1 . Battery voltage should be indicated. If battery voltage is indicated, go to next step. If zero volts are indicated, repair circuit No. 414 (Orange/Red wire) for open. Repeat SERVICE BAY DIAGNOSTICS under TESTING & DIAGNOSIS.
    Fig 1: Relay Circuit Check
    G92E04019
  6. Turn air suspension switch to OFF position. Disconnect control module connectors. Measure resistance of circuit No. 420 (Dark Blue/Yellow wire) between fuse/relay box and pin No. 23 of control module BLACK connector. Resistance should be less than 10 ohms. See Figure . If resistance is less than 10 ohms, replace control module. Repeat SERVICE BAY DIAGNOSTICS under TESTING & DIAGNOSIS. If resistance is 10 ohms or greater, repair open in circuit No. 420 (Dark Blue/Yellow wire). Repeat SERVICE BAY DIAGNOSTICS under TESTING & DIAGNOSIS.
  7. Remove air compressor relay from fuse/relay box. Disconnect air compressor connector. Measure resistance of circuit No. 578 (Light Blue/Pink wire) between fuse/relay box and compressor connector. Resistance should be less than 5 ohms. See Figure . If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or greater, repair open in circuit No. 578 (Light Blue/Pink wire). Repeat SERVICE BAY DIAGNOSTICS under TESTING & DIAGNOSIS.
  8. Measure resistance between circuit No. 57 (Black wire) at compressor connector and ground. If resistance is less than 5 ohms, replace compressor assembly. Repeat SERVICE BAY DIAGNOSTICS under TESTING & DIAGNOSIS. If resistance is 5 ohms or greater, repair open in circuit No. 57 (Black wire). Repeat SERVICE BAY DIAGNOSTICS under TESTING & DIAGNOSIS.
  9. Enter Functional Test Code 33. See FUNCTIONAL TEST under TESTING & DIAGNOSIS. Leave air suspension switch on and raise vehicle on hoist. Feel each spring solenoid valve to see if they are cycling. If valves are cycling, go to test 14). If one or both valves do not cycle, DO NOT exit Functional Test Code 33. Go to next step.
  10. Disconnect inoperative spring solenoid connector. Measure voltage between both circuits in connector. If voltmeter pulses, replace inoperative spring solenoid valve. If meter does not pulse, exit Functional Test Code 33 and go to next step.
  11. Measure voltage between circuit No. 414 (Orange/Red wire) at spring solenoid connector and ground. Battery voltage should be indicated. If battery voltage is indicated, go to next step. If zero volts are indicated, repair open in circuit No. 414 (Orange/Red wire). See Figure .
    NOTE: Repeat SERVICE BAY DIAGNOSTICS under TESTING & DIAGNOSIS to verify repairs.
  12. Turn air suspension switch to OFF position. Disconnect control module connectors. Measure resistance of left spring solenoid control circuit between solenoid connector and Black control module connector pin No. 13. Repeat procedure on right air spring solenoid connector and Black control module connector pin No. 25. If resistance in either/or both circuits is less than 10 ohms, go to next step. If resistance is 10 ohms or greater, repair open in circuit No. 416 (Light Blue/Black wire) and/or circuit No. 429 (Purple/ Light Green wire).
    NOTE: Resistance measurements in the following procedure check condition of air spring solenoid valve coil and diode. Digital ohmmeters will not pass enough current through diode to check its condition. Use Rotunda Tester (059-00010) or equivalent analog ohmmeter.
  13. Turn air suspension switch to OFF position. Disconnect control module connectors. Turn air suspension switch to ON position. Measure resistance between pins No. 13 and 1 on control module connectors. Reverse leads and measure resistance again between pins. No. 13 and 1 of control module connectors. Ohmmeter should indicate 15-18 ohms one way, and 5-10 ohms less the other way. See Figure . If higher reading is 15-18 ohms and lower reading is 5-10 ohms less than higher reading, go to next step. If both readings are the same or 0-18 ohms, replace defective spring solenoid.
  14. Measure resistance between pins No. 25 and 1 on control module connectors. Reverse leads and measure resistance again between pins No. 25 and 1 on control module connectors. Ohmmeter should read 15-18 ohms one way, and 5-10 ohms less the other way. See Figure . If higher reading is 15-18 ohms and lower reading is 5-10 ohms less than higher reading, replace control module. If both readings are the same or 0-18 ohms, replace defective spring solenoid.
  15. Leave Super Star II tester in Functional Test mode, but do not select test code (tester button should be depressed down). Leave air suspension switch in ON position. Making sure Super Star II tester is within reach, raise vehicle on hoist. Ensure height sensor is attached to both ball studs. Height sensor damage must be repaired before continuing.
  16. Lower vehicle and support on frame. If rear of vehicle is supported by axle, air springs will be damaged during this test. Disconnect air line from air drier. Enter Functional Test Code 26 (compressor rear). See FUNCTIONAL TEST under TESTING & DIAGNOSIS. Air should flow from air drier while compressor is running. If air flows from air drier, exit Functional Test Code 26. Connect air line to drier and go to step 18). If there is little or no airflow from air drier, exit Functional Test Code 26 and go to next step.
  17. Remove air drier from air compressor. Enter Functional Test Code 26 (compress rear). See FUNCTIONAL TEST under TESTING & DIAGNOSIS. Air should flow from air drier fitting on compressor while compressor is running. If there is airflow from compressor, replace air drier. If there is little or no airflow from compressor, replace compressor assembly. Repeat SERVICE BAY DIAGNOSTICS under TESTING & DIAGNOSIS.
    CAUTION: Enter Functional Test Code 26 (compress rear) and fill air springs for about 90 seconds before lowering rear of vehicle.
  18. Raise rear of vehicle. Support rear of vehicle on frame not on axle. Supporting vehicle by frame allows full extension of air springs for leak detection. Enter Functional Test Code 26 (compress rear). See FUNCTIONAL TEST under TESTING & DIAGNOSIS. Check air lines and air springs for leaks. If leaks are detected, exit Functional Test Code 26. Repair leaks in air lines and/or replace air spring(s). If no leaks are detected, go to next step.
    NOTE: Air lines are routed along left rocker panel along with fuel and brake lines.
  19. Disconnect air lines at air spring solenoid valves and remove heat shields if equipped. Support rear of vehicle on frame to prevent vehicle from lowering during functional test. Enter Functional Test Code 26 (compress rear). See FUNCTIONAL TEST under TESTING & DIAGNOSIS. Air should flow from both air lines and from both air spring solenoid valves. If there is no airflow from air lines, repair blocked air lines. If there is no airflow from air spring(s), replace air spring solenoid(s). If there is airflow from both air lines, replace control module.
NOTE: Repeat SERVICE BAY DIAGNOSTICS under TESTING & DIAGNOSIS to verify repairs.
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