Diagnostic Procedure

2000 Saturn SC2 Automatic, MP6SECTION Diagnostic Procedure
  1. Start engine and operate engine at idle until closed-loop status is reached. Using scan tool, perform AIR PUMP SPECIAL BAY TEST while monitoring AIR SYS. LAST TEST. If scan tool indicates PASS, see DIAGNOSTIC AIDS  . If scan tool does not indicate PASS, go to next step.
  2. If air pump turned on during test, go to next step. If air pump did not turn on during test, check AIR PUMP fuse (30-amp) located in underhood junction block. Replace fuse. If fuse is okay, go to step  6 .
  3. Check vacuum hoses, IAT hose, in-line check valve and pipe for leaks or restrictions. Repair or replace as necessary. If no leaks or restriction is found, go to next step.
  4. Turn ignition on, with engine off. Disconnect combination valve vacuum line. Using a hand-held vacuum pump, apply 15 in. Hg to combination valve. If vacuum holds, go to next step. If vacuum does not hold, replace combination valve.
  5. Disconnect combination valve air hose. Using scan tool, command air pump relay on. If air is blowing from hose, replace air pump solenoid. If air is not blowing from hose, replace air pump.
  6. Disconnect air pump harness connector. Connect a test light between air pump harness connector terminals. Using scan tool, command AIR PUMP RELAY on. If test light illuminates, replace air pump. If test light does not illuminate, go to next step.
  7. Connect test light between ground and air pump harness connector terminal "A" (Red wire). Using scan tool, command air pump relay on. If test light illuminates, go to next step. If test light does not illuminate, repair open in air pump ground circuit (Black wire).
  8. Verify if relay clicks. If relay clicks, check for open in air pump circuit (Red wire) between air pump and underhood fuse/relay block or for terminal tightness. Repair as necessary. If relay did not click, replace air pump relay.
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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.