LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Volvo >> 1983 >> 242 GLT, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Fuel Injection System - BOSCH LH >> Testing >> Components & Wiring Check
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Components & Wiring Check

  1. Turn the ignition off. Remove the panel located in front of the right front door. Remove the connector from the control unit. Push catch to side and fold out connector.
  2. Remove the connector cover.
    CAUTION: Never check terminals from the front. Experience has shown that terminals are easily damaged causing further faults
  3. Check terminals through the holes in side of connector. Do not use excessive force. Terminal numbers are stamped on the connector.
  4. Check the grounds by connecting an ohmmeter between ground and terminals 11 and 25. Resistance should be zero for both terminals. Wires are grounded at the intake manifold.
  5. Check the current supply by first switching on the ignition. Connect a voltmeter between ground and terminal 18. The meter should show battery voltage. Switch off the ignition.
  6. Check the shielding wires. Make sure that the wires are twisted together and connected to terminal 5.
  7. Check the pump relay. First switch on the ignition, then ground terminal 17. The relay should switch on and fuel pumps start. Turn off the ignition.
  8. Check the system relay. Connect a voltmeter between ground and terminal 9. Ground terminal 21. The relay should switch on and meter show battery voltage.
  9. Check the air mass meter current supply and ground. Ground terminal 21. Peel back rubber boot from around air mass meter wiring connector. Connect a voltmeter between terminal 9 and ground and then between terminals 9 and 36. Meter should show battery voltage in both cases. (Air mass meter is grounded at intake manifold). Reposition rubber boot around wiring connector.
  10. Check the wiring from starter motor. Connect a voltmeter between ground and terminal 4. Crank the engine and the meter should show battery voltage.
  11. Check the wiring from the ignition coil. Turn on the ignition. Connect a voltmeter between ground and terminal 1. Meter should deflect. Turn the ignition off.
  12. Check the injectors. Connect an ohmmeter between pump relay terminal 87 and control unit connector terminal 13. The correct resistance is approximately 4 ohms. If the meter shows approximately 5.3 ohms, then either an injector or injector wire is defective. If the meter shows approximately 8 ohms, then two injectors or injector wires are defective. If the meter shows approximately 16 ohms, then three injectors or injector wires are defective. If the injectors or injector wires are defective, then remove the injector connectors and check each separately. The resistance for each injector should be 16 ohms.
  13. Check the temperature sensor by connecting an ohmmeter between ground and terminal 2. The resistance depends on the temperature. See TEMPERATURE RESISTANCE  table. Incorrect test values mean defective temperature sensor. Extremely high test values indicates open circuit in temperature sensor or wiring. Check temperature sensor ground at intake manifold. Zero resistance indicates a short circuit.
    TEMPERATURE RESISTANCE

    Temperature Resistance (Ohms)
    +80°C (175°F) 290-364
    +20°C (68°F) 2280-2720
    -10°C (14°F) 8260-10560
  14. Check the air mass meter by connecting an ohmmeter between terminals 6 and 7 and then 6 and 14. Resistance between terminals 6 and 7 should be 3.7 ohms. Resistance between terminals 6 and 14 should be 0-1000 ohms (resistance varies depending on CO-adjustment screw position).
  15. Check the throttle valve switch. Connect an ohmmeter between ground and terminal 3. Depress accelerator pedal. Meter should show zero resistance in idle position and infinite resistance in other positions. Connect ohmmeter between ground and terminal 12. Depress accelerator pedal. Meter should show zero resistance in full throttle position and infinite resistance in other positions. If incorrect, check throttle valve switch ground at intake manifold. If ground connection is OK, then replace throttle valve switch.
  16. Check air control valve. Connect ohmmeter between pump relay terminal 87 and control unit connector terminal 10 and then between pump relay terminal 87 and control unit connector terminal 23. Resistance should be approximately 20 ohms in both cases.
  17. Check micro-switch for air conditioning. Connect ohmmeter between ground and terminal 16. Turn knob on A/C control panel. Resistance should decrease.
  18. Install control unit connector cover. Plug in control unit connector. The ignition should be turned off.
scientia non olet · About LEMON Manuals