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HOMESERVICE MANUALSPLYMOUTH1994LASER RS TURBO, AWD, AUTOMATICREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCETESTING & DIAGNOSISENGINE CONTROLS - TESTS W/CODES - 1.8LDIAGNOSTIC CHARTSTEST DR-16A - TESTING IDLE SPEED CONTROL ACTUATOR
1994 Plymouth Laser RS Turbo, AWD, Automatic

Test Dr-16A - Testing Idle Speed Control Actuator

1994 Plymouth Laser RS Turbo, AWD, AutomaticSECTION Test Dr-16A - Testing Idle Speed Control Actuator
NOTE: For connector terminal identification, see CONNECTOR IDENTIFICATION . For appropriate wiring diagram, see WIRING DIAGRAMS .
  1. Using DRB, read timing advance. While monitoring DRB display, set engine speed to 2000 RPM. If timing advance does not increase, replace Electronic Control Unit (ECU). Perform TEST VER-2 .
  2. If timing advance increases, allow engine to idle. Disconnect Idle Speed Control (ISC) actuator. While observing engine RPM, actuate injector No. 1. If engine RPM does not drop, go to step 17). If engine RPM drops, actuate fuel injector No. 2. If engine RPM does not drop, go to step 17). If engine RPM drops, go to next step.
  3. Actuate injector No. 3. If engine RPM does not drop, go to step 17). If engine RPM drops, actuate injector No. 4. If engine RPM does not drop, go to step 17). If engine speed drops, stop actuation test. Reconnect ISC actuator connector.
    NOTE: Engine should still be running for following step.
  4. Read Automatic Idle Speed (AIS) value. While monitoring DRB display, disconnect injector No. 1. If AIS value changes, reconnect injector No. 1. Perform TEST DR-17A. If AIS value does not change, reconnect injector No. 1. Turn ignition switch to OFF position. Disconnect Electronic Control Unit (ECU) 18-pin connector.
  5. Measure resistance between ECU 18-pin connector terminals No. 58 and 59 (Dark Blue/White and Dark Green/Black wires). If resistance is 5-35 ohms, go to step 8). If resistance is not 5-35 ohms, disconnect ISC actuator connector. Measure resistance across ISC actuator terminals. If resistance is not 5-35 ohms, replace ISC actuator. Perform TEST VER-2.
  6. If resistance is 5-35 ohms, measure resistance between ECU connector terminal No. 58 (Dark Blue/White wire) and ground. If resistance is less than 10 ohms, repair Dark Blue/White wire for a short to ground. Perform TEST VER-2. If resistance is more than 10 ohms, measure resistance of Dark Blue/White wire between ECU 18-pin connector terminal No. 58 and ISC connector terminal No. 1.
  7. If resistance is more than 10 ohms, repair open Dark Blue/White wire. Perform TEST VER-2. If resistance is less than 10 ohms, measure resistance between Dark Green/Black wire and ground. If resistance is more than 10 ohms, repair open Dark Green/Black wire. Perform TEST VER-2. If resistance is less than 10 ohms, repair Dark Green/Black wire for a short to ground. Perform TEST VER-2.
  8. Observe ISC actuator while connecting a 6-volt battery across ECU terminals No. 58 and 59. Reverse polarity at 6-volt battery. If ISC actuator does not retract or extend, replace ISC actuator. Perform TEST VER-2 .
  9. If ISC actuator retracts or extends, disconnect 6-volt battery. Disconnect motor position sensor 6-pin connector. Turn ignition switch to ON position. Measure voltage between motor position sensor connector terminal No. 6 (Dark Green/Red wire) and ground. If voltage is less than 4 volts, go to step 15).
  10. If voltage is more than 4 volts, measure voltage at motor position sensor terminal No. 5 (Brown wire). If voltage is more than 4 volts, go to step 13). If voltage is less than 4 volts, turn ignition switch to OFF position.
  11. Disconnect ECU 24-pin connector. Measure resistance between motor position sensor connector terminal No. 5 (Brown wire) and ground. If resistance is less than 10 ohms, repair Brown wire for a short to ground. Perform TEST VER-2.
  12. If resistance is more than 10 ohms, measure resistance of Brown wire between ECU 24-pin connector terminal No. 17 and motor position sensor connector terminal No. 5. If resistance is less than 10 ohms, replace ECU. Perform TEST VER-2. If resistance is more than 10 ohms, repair open Brown wire. Perform TEST VER-2.
  13. Turn ignition switch to OFF position. Measure resistance between motor position sensor connector terminal No. 3 (Dark Green/Black wire) and ground.
  14. If resistance is less than 10 ohms, replace motor position sensor. Perform TEST VER-2. If resistance is more than 10 ohms, repair open Dark Green/Black wire between ECU 24-pin connector terminal No. 24 and motor position sensor connector terminal No. 3. Perform TEST VER-2.
  15. Turn ignition switch to OFF position. Disconnect ECU 24-pin connector. Measure resistance between motor position sensor connector terminal No. 6 (Dark Green/Red wire) and ground. If resistance is less than 10 ohms, repair Dark Green/Red wire for a short to ground. Perform TEST VER-2 . If resistance is more than 10 ohms, measure resistance of Dark Green/Red wire between ECU 24-pin connector terminal No. 13 and motor position sensor connector terminal No. 6.
  16. If resistance is less than 10 ohms, replace ECU. Perform TEST VER-2. If resistance is more than 10 ohms, repair open Dark Green/Red wire. Perform TEST VER-2.
  17. Stop actuation test. Connect a scope to secondary ignition. Check secondary ignition. If secondary ignition system is not okay, repair as required. Perform TEST VER-2. If secondary ignition system is okay, check for engine mechanical defects. Repair as required. Perform TEST VER-2.
RENDER: 1.0x

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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.