1993 Volvo 850 AutomaticFACTORY OEM SERVICE PROCEDURE

Power Circuit Check

  1. Connect voltmeter between measuring unit terminals No. 20 and 43. Operate starter motor. Voltmeter should indicate .7-1.3 volts. If voltage is not as specified, repeat test using new ECU.
  2. To check distributor ignition signal to fuel injection ECU, connect voltmeter between measuring unit terminals No. 20 and 52. Operate starter motor. Voltmeter should indicate about 5-7 volts. If voltage is not as specified, repeat test using new distributor ignition ECU.
  3. Turn ignition off. To check voltage supply to ECU, connect voltmeter between measuring unit terminals No. 20 and 10. Battery voltage should be present. Turn ignition on. Connect voltmeter between measuring unit terminals No. 20 and 30. Battery voltage should be present. If battery voltage is not present, check wiring.
Factory Service Tools

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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.

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