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Home >> Saturn >> 2000 >> SC2 Automatic, MP6 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P1635: 5-Volt Reference Circuit >> Diagnostic Procedures
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Diagnostic Procedures

NOTE: A short to battery voltage in 5-volt reference circuit will not set this DTC.
  1. Turn ignition on, with engine off. Wait 10 seconds. Using scan tool, monitor status of this DTC. If scan tool indicates that DTC P1635 is active, go to next step. If scan tool does not indicate that DTC P1635 is not active, problem is intermittent. See DIAGNOSTIC AIDS  .
  2. Disconnect one sensor at a time while monitoring voltage to another sensor on the 5-volt reference line using scan tool. When one sensor is left connected, reconnect a sensor that was previously disconnected, then disconnect the last sensor. Monitor scan tool voltage reading. If voltage on monitored sensor changes to a normal reading when another sensor is disconnected, replace affected sensor. If voltage on monitored sensor does not change to normal reading when another sensor is disconnected, go to next step.
  3. Turn ignition off. Disconnect PCM harness connector J1. Check continuity between 5-volt reference circuit and chassis ground and between 5-volt reference circuit and ground circuit at harness connector on each sensor (TP, MAP, EGR and fuel tank pressure sensor). If continuity exists on any of the circuits, repair short in affected circuit. If continuity does not exist on any of the circuits, replace PCM.
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