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Home >> Volvo >> 2000 >> S70 AWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics - Turbo >> Diagnostic Tests >> P1528/ECM-91CF: Engine Control Module Internal Fault >> Diagnostic Procedure
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Diagnostic Procedure

  1. DTC can be caused by CAN related problems. Read out fault memory. If DTCs related to CAN exist, repair these first. If this DTC resets after repairing CAN related DTCs, go to next step.
  2. Check DTC status to see if fault is intermittent or permanent. Connect a scan tool and start engine. Hold down brake pedal and press accelerator pedal down simultaneously. Fault is intermittent if RPM increases. Fault is permanent if RPM does not increase. If fault is permanent, go to next step.
  3. Connect breakout box. See CONNECTING & DISCONNECTING BREAKOUT BOX .
  4. Check for voltage via fuse for stop lamp switch. Check signal cable between brake light switch terminal No. 2 and ECM terminal B26 for a short to ground. Repair as necessary and go to next step.
  5. Check between ECM terminal A38 and throttle unit terminal No. 2 for a short to ground. Repair as necessary and go to next step.
  6. Check signal cable between brake light switch terminal No. 2 and ECM terminal B26 for an open circuit. Repair as necessary and go to next step.
  7. Check between ECM terminal A38 and throttle unit terminal No. 2 for an open circuit. Repair as necessary and go to next step.
  8. Disconnect breakout box when wiring diagnosis is complete. Verify repair. Ignition OFF. Ensure all components and connectors are installed correctly. Connect a scan tool and turn ignition ON. Read out fault memory. If DTC is no longer present, repair is complete. If DTC remains, go to next step.
  9. ECM has registered an internal fault. Replace with a known good unit. See REMOVAL, OVERHAUL & INSTALLATION - EXCEPT S40 & V40 article. Verify repair when complete and clear fault memory. If DTC is no longer present, repair is complete.
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