1998 Cadillac CateraFACTORY OEM SERVICE PROCEDURE

Multi-Ram System Diagnosis

NOTE: Powertrain Control Module (PCM) may also be referred to as Engine Control Module (ECM).
  1. If powertrain OBD system check has been performed, go to next step. If powertrain OBD system check has not been performed, perform powertrain OBD system check. See POWERTRAIN OBD SYSTEM CHECK in TESTS W/CODES article.
  2. Connect scan tool to data link connector. Retrieve DTCs. If DTCs do not exist, go to next step. If DTCs exist, perform appropriate DTC test. See TESTS W/CODES article.
  3. Visually inspect system. Check for disconnected or damaged vacuum hoses and/or components. Check linkage between vacuum actuators and valves for binding or interference with hoses. Ensure wiring is routed properly and not damaged. If problem does not exist, go to next step. If problem exist, repair as necessary, then go to step 14).
  4. Start engine and observe vacuum actuator linkages for switchover valves. Using scan tool, command each valve on and off. If both valves operate, go to next step. If both valves do not operate, go to step 6).
  5. Turn ignition switch to LOCK position. Remove duct from between intake resonance switchover valve and throttle body. Hold throttle plates open to view moveable divider in back of intake manifold. Move actuator linkage by hand and ensure divider moves with linkage. Look down passages in intake resonance switchover valve to view moveable divider between 2 sides of valve. Move actuator linkage by hand to ensure divider moves with linkage. If both valves operate properly, system is okay. If either valve does not operate, go to step 13).
  6. Using scan tool, exit device control. Disconnect manifold vacuum supply hose at solenoid valve while observing actuator linkage. If actuator does not move when vacuum is disconnected, go to next step. If actuator moves when vacuum is disconnected, replace solenoid valve, then go to step 10).
  7. Check for vacuum at manifold vacuum supply hose. If vacuum exists, go to next step. If vacuum does not exist, go to step 11).
  8. Disconnect other hose from solenoid valve and connect hoses together using suitable vacuum connector. If actuator linkage does not operate, go to next step. If linkage operates, go to step 10).
  9. Disconnect vacuum hoses from actuator. If vacuum exists, go to step 13). If vacuum does not exist, go to step 12).
  10. Replace solenoid valve and go to step 14).
  11. Repair vacuum supply hose or plugged vacuum source and go to step 14).
  12. Repair vacuum hose to actuator and go to step 14).
  13. Replace valve/actuator assembly and go to step 14).
  14. Start engine. Observe vacuum actuator linkages for switchover valves. Using scan tool, command each valve on and off. If both valves operate, system is okay. If both valves do not operate, go to step 2).
Factory Service Tools

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.