LEMON Manuals: Even more car manuals for everyone
Home >> Geo >> 1996 >> Metro Base, 4D Sedan, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes >> Circuit Tests >> DTC P0505 - Idle Control System >> Diagnosis & Repair

Diagnosis & Repair

  1. Connect scan tool to DLC. Start engine and allow to reach normal operating temperature. Clear DTC. Select RPM control on scan tool. Observe ISC plunger while attempting to raise and lower idle speed with scan tool. If ISC plunger extends and retracts, go to next step. If ISC plunger does not move, go to step 4).
  2. Turn ignition on. Review FREEZE FRAME data. Select CLEAR INFORMATION function. Operate vehicle within FREEZE FRAME conditions. If DTC P0505 resets, go to next step. If DTC P0505 does not reset, check for an intermittent problem. See TESTS W/O CODES article.
  3. Disconnect ISC motor relay, located in engine compartment relay/fuse box. Turn ignition on. Using a test light connected to ground, probe ISC connector terminal No. 1 (White/Blue wire). If test light comes on, go to next step. If test light does not come on, repair open in White/Blue wire.
  4. Using an ohmmeter, measure resistance of ISC relay between terminals No. 3 (Gray wire) and No. 4 (Gray/Yellow wire). If continuity does not exist, go to next step. If continuity exists, replace ISC motor relay. Retest system.
  5. Measure resistance of ISC motor relay between terminals No. 1 (White/Blue wire) and No. 2 (Gray/Black wire). If resistance is 75-95 ohms, go to next step. If resistance is not as specified, replace ISC motor relay. Retest system.
  6. Disconnect PCM connector. Using a fused jumper wire, connect ISC motor relay connector terminal No. 2 (Gray/Black wire) to battery positive terminal. Using a voltmeter, measure voltage at PCM connector C1, terminal No. 16 (Gray/Black wire). If reading is battery voltage, go to next step. If battery voltage does not exist, repair open or short in Gray/Black wire. Retest system.
    NOTE: In next step, DO NOT apply 6 volts to ISC control circuit longer than one second.
  7. Turn ignition off. Disconnect PCM connector C1. Backout terminals No. 11 (Gray/Yellow wire), No. 16 (Gray/Black wire), and No. 24 (Gray/Red wire). Reconnect PCM connector. Using a fused jumper wire, connect Gray/Black wire to ground. Turn ignition on. Ensure ISC plunger contacts throttle lever. Connect 4 1.5 volt batteries in series. Connect Gray/Yellow wire to positive side of batteries. Connect Gray/Red wire to negative side of batteries. Ensure CTP switch parameter on scan tool reads ON. If display reads OFF, move ISC actuator and turn CTP switch ON. If ISC plunger extends, go to next step. If ISC plunger does not extend, go to step 10).
  8. Turn ignition on. Ensure ISC plunger contacts throttle lever. Connect Gray/Yellow wire to negative side of batteries. Connect Gray/Red wire to positive side of batteries. Ensure CTP switch parameter on scan tool reads ON. If display reads OFF, move ISC actuator and turn CTP switch ON. If ISC plunger retracts, go to next step. If ISC plunger does not retract, go to step 10).
  9. Turn ignition off. Disconnect batteries and reinstall wire terminals into PCM connector. Reconnect PCM. Turn ignition on. Disconnect ISC motor connector. Using a test light connected to battery positive terminal, probe Black/Blue wire of ISC motor connector. If test light comes on, replace PCM. If test light does not come on, repair open in Black/Blue wire. Retest system.
  10. Check ISC motor control circuits (Gray/Yellow, Gray/Red and Gray wires) between ISC motor relay and ISC motor. Repair as necessary. If wires are okay, replace ISC motor. Retest system.
scientia non olet · About LEMON Manuals