Part 5: Wiring Block Diagram

Basic Circuits

Block Diagram


The Block Diagram shows the basic connection paths used for successful operation. The arrows indicate the primary direction of the control or communication. It is important to consider the Engine & ECU Wiring harness complete with all associated sensors as a complete single unit. While some parts of the Engine & ECU Wiring Harness may need to be adapted to suit your vehicle configuration the overall harness should not be varied greatly. For details of individual sensor wiring refer to the electronic version of the Ford Focus Wiring Diagrams.

The OEM Engine Control Unit is designed to be located within the engine bay and only needs to be mounted with the connectors protected from direct water ingress.

Part 4: Connector Pinouts

Connector Pin-out Diagrams

C90 – Engine Loom to Main Junction Box


  1. 5-EC7D (BU/RD)
    5-EC7C (BU/RD)
    5-EC7A (BU/RD) – DURATEC 2.0L – HIGH CAN-
  2. 91S-RH15 (BK/YE)
  3. Not Used
  4. 31S-BB16 (BK/RD)
    31S-BB16B (BK/RD)
    31S-BB16A (BK/RD) – DURATEC 2.0L – Starter Relay Trigger Ground (PCM controls Ground for Starter Relay Coil, supplied from IGN Switch START position)
  5. 91S-RE8 (BK/YE)
    31S-FA11A (BK/YE)
  6. 91S-RH5 (BK/BU) – DURATEC 2.0 – Fuel Pump Relay Trigger (Grounds coil for fuel pump relay via inertia switch is fitted. Connects to PCM on C690 Pin 19)
    91S-RH5A (BK/BU)
    91S-RH5B (BK/BU)
    15S-PE8 (GN/RD)
  7. Not Used
  8. 15S-LG23 (GN/WH) – DURATEC 2.0L – Brake Pedal Detection (Ground for the Brake light Circuit connects to PCM via C690 Pin 39)
    15S-LG23B (GN/WH)
    15S-LG23A (GN/WH)
  9. Not Used
  10. 15-LG28 (GN/WH)
    15-LG28A (GN/WH)
  11. 50-BB12 (GY)
    50-BB14A (GY/RD) – DURATEC 2.0L – Starter Solenoid Power (via Transmission Selector switch to starter motor, Controlled by Starter Relay)
  12. 15-RJ15 (GN/BU) – DURATEC 2.0L – PCM +12v via Power Hold Relay
    15-RJ15A (GN/BU)
    15-RR1 (GN/RD) – DURATEC 2.0L – Ignition Coil Power (+12v via Power Hold Relay. Coils ground by PCM for ignition)
    15S-RL42 (GN/BU)
    15S-RL50 (GN/BU)
  13. 30-RE8 (RD)
    30-RE8A (RD)
    30-RE8B (RD)
    30-TA55 (RD) – DURATEC 2.0L – Transmission Control Unit +12v Battery (Connects to Transmission Control Unit via C117 & C414)
  14. 15-RN3A (GN/BU) – DURATEC 2.0L – Injector Power (via Power Hold Relay, injectors Ground controlled by PCM)
    15-RN3C (GN/BU)
    15-RN3 (GN/BU)
  15. 4-EC7D (GY/RD)
    4-EC7B (GY/RD) – DURATEC 2.0L – HIGH CAN+
    4-EC7A (GY/RD)
  16. 8-EE14 (WH/BU)
  17. 31S-FA11 (BK/YE) – DURATEC 2.0L – Wide Open Throttle Relay trigger (PCM grounds coil to activate)
    91S-RE8A (BK/YE)
  18. 15S-FA6 (GN/YE) – DURATEC 2.0L – A/C Compressor Clutch via WOT Relay
    15S-FA6A (GN/YE)
  19. 8-FA88 (WH/VT) – DURATEC 2.0L – A/C Pressure Sensor Signal (From PCM to pressure sensor)
    91S-PA13 (BK/BU)
    8-FA88A (WH/VT)
    8-FA88B (WH/VT)
  20. 30-BA10 (RD) – DURATEC 2.0L – +12v Battery to Alternator
  21. 91S-RH9 (BK/BU)
    91S-RH9A (BK/BU) – DURATEC 2.0L – Power Hold Relay Trigger (Grounds coil for Power Hold Relay) Connects to PCM at C690 Pin 35.
    91S-RH9B (BK/BU)
  22. 91S-LG45 (BK/GN) – DURATEC 2.0L – Reverse Light Relay trigger (Reverse light relay coil triggered when in Reverse by Transmission Control Unit)
  23. NOT USED
  24. 15S-RD15D (GN/OG)
    15-TA55 (GN/BK) – DURATEC 2.0L – Transmission Control Unit +12v via Power Hold Relay
    15-TA18 (GN/OG) – DURATEC 2.0L – Transmission Range Sensor +12 via Power Hold Relay
  25. 15S-RD15C (GN/OG)
    91S-BB6 (BK/YE)
  26. 15S-RD15B (GN/OG)
  27. 15S-RD15A (GN/OG)
  28. 10-RJ30 (GY) – DURATEC 2.0L – Accelerator Pedal Position Sensor Signal (From Accelerator pedal unit)
  29. 7-FA88 (YE/VT) – DURATEC 2.0L – A/C Pressure Sensor VCC (PCM to pressure sensor)
    7-FA88A (YE/VT)
  30. 8-PF36 (WH/GN) – DURATEC 2.0L – Auto Transmission Shift Up (Connects to Transmission Control Unit via C117 & C414)
    8-PF36A (WH/GN)
  31. NOT USED
  32. 9-FA88 (BN/WH) – DURATEC 2.0L – A/C Pressure Sensor Ground (Connects output of pressure sensor to PCM)
    9-FA88A (BN/WH)
  33. 10-PF36 (GY/OG) – DURATEC 2.0L – Auto Transmission Shift Down (Connects to Transmission Control unit via C117 & C414)
  34. 49-PA6 (BU) – DURATEC 2.0L – Radiator Fan Control trigger (PCM grounds coil of relay to trigger radiator fan)
  35. NOT USED
  36. NOT USED
  37. 15-RE17 (GN/BU)
    15-RE17A (GN/BU) – DURATEC 2.0L – PCM Power +12v IGN in RUN or START (Connects to PCM via C690 pin 46)
    15-RN2A (GN/BU)
    15-RN2B (GN/BU)
  38. NOT USED
  39. 15S-LG9 (GN/BK)
    15S-LG9A (GN/BK)
  40. 15-RJ14 (GN/YE) – DURATEC 2.0L – Rear O2 Sensor Power (+12v via Power Hold Relay)
    15-RJ25 (GN/RD) – DURATEC 2.0L – Front O2 Sensor Power (+12v via Power Hold Relay)
    15-RR4 (GN/BU)
  41. 15-RE21 (GN/OG)
    15-RE21A (GN/OG) – DURATEC 2.0L – PCM Power (+12v via Power Hold Relay)
    15-RE21B (GN/OG)

 C200 – On-Board-Diagnostic Port


  1. Not Used
  2. Not Used
  3. 4-EC10B (GY) – HIGH CAN-
  4. 31-RA1 (BK) – Ground
  5. 91-RA1 (BK/OG) – Ground
  6. 4-EC7L (GY/RD) – HIGH CAN+
  7. Not Used
  8. Not Used
  9. Not Used
  10. Not Used
  11. 5-EC10B (BU) – MID CAN-
  12. Not Used
  13. Not Used
  14. 5-EC7L (BU/RD) – MID CAN+
  15. Not Used
  16. 29-RA1 (OG) – +12v Battery

C391 – PATS Key/Transponder Reader


  1. 15-GL37 (GN/BK) – +12v START / RUN from IGN Switch
  2. 91-GL1 (BK/YE) – Ground
  3. 10-GL37 (GY/OG) – Sensor (Connects to Instrument Cluster via C809 Pin 5)
  4. 8-GL37 (WH/GN) – Sensor (Connects to Instrument Cluster via C809 Pin 3)

C456 – Ignition Key Switch


  1. 15-DA1 (GN/YE) – +12v START/RUN (Distribution)
  2. 30S-LE29 (RD/GN)+12v Battery
  3. 31S-TA32 (BK/WH) – Ground Key Inhibit (Connects to C809 Pin25)
  4. 30-BB9 (RD) – +12v Battery (20A Fused Supply)
  5. Not Used
  6. 75-DA1 (YE) – +12 Accessory (Distribution)
  7. 50-BB16 (GY/BK) – +12v START Only (Connects to Starter Relay)

C648 – Accelerator Pedal Unit


  1. 7-RJ30 (YE) – +5v Constant Voltage (Connects to C809 Pin31)
  2. 8-RJ30 (WH) – Accelerator Pedal Position Validation Sensor+ (Connects to C809 Pin14)
  3. 9-RJ30 (BN) – Accelerator Pedal Position Validation Sensor- (Connects to C809 Pin 13)
  4. 91-RJ30 (BK/YE) – Ground
  5. 10-RJ30 (GY) – Accelerator Pedal Position Sensor (Connects to ECU Directly via C90 Pin 28)
  6. 15-RJ30 (GN/YE) – +12v START/RUN (Connects to IGN Switch via C456 Pin 1)

C732 – Fuel Pump Connector


  1. 15S-RG2 (GN/OG) – +12v START/RUN via Fuel Pump Relay (10A Fused)
  2. 8-GA7 (WH/RD) – Fuel Level Sensor+(Connects to C809 Pin 8)
  3. Not Used
  4. 9-GA7 (BN/RD) – Fuel Level Sensor Ground (Connects to C809 Pin 9)
  5. 31-RG2 (BK) – Ground
  6. Not Used

C809 – Instrument Cluster


  1. 15S-LD13 (GN/OG)
  2. 91S-GE56A (BK/YE)
  3. 8-GL37 (WH/GN) – PATS Key Reader (Connects to C391 Pin 4)
  4. 15-GG14 (GN/RD) – +12v START/RUN Cluster Power (Connects to C456 Pin 1)
  5. 10-GL37 (GY/OG) – PATS Key Reader (Connects to C391 Pin 3)
  6. 91-GG14 (BK/OG) – Ground
  7. 9-GA7 (BN/RD) – Fuel Level Sensor Ground (Connects to C732 Pin 4)
  8. 8-GA7 (WH/RD) – Fuel Level Sensor+ (Connects to C732 Pin 2)
  9. 29S-GG14 (OG) – +12v Constant Power
  10. 91S-BB6 (BK/YE) – Ground
  11. Not Used
  12. Not Used
  13. 9-RJ30 (BN) – Accelerator Pedal Position Validation Sensor- (Connects to C648 Pin 3)
  14. 8-RJ30 (WH) – Accelerator Pedal Position Validation Sensor+ (Connects to C648 Pin 2)
  15. 75-GG14 (YE/BU) – +12v Accessory Power (Connects to C456 Pin 6)
  16. 15S-LD7 (GN/BU)
  17. 5-EC7H (BU/RD) – MID CAN+
  18. 4-EC7H (GY/RD) – HIGH CAN+
  19. Not Used
  20. Not Used
  21. Not Used
  22. 5-EC10 (BU) – MID CAN-
  23. 4-EC10 (GY) – HIGH CAN-
  24. Not Used
  25. 31S-TA32 (BK/WH) – Ground
  26. Not Used
  27. 91S-GG6 (BK/RD) –
  28. Not Used
  29. 91S-PG6 (BK/YE) – Ground
  30. 91S-GE56 (BK/YE) – Ground
  31. 7-RJ30 (YE) – +5v Supply Constant (Connects to C648 Pin 1)
  32. 29-GG14 (OG) – +12v Battery Supply (Connects to C456 Pin 4)

Part 3: Donor Vehicle Connector Locations

Connector Locations

Due to the modular design of the Ford Focus wiring loom there are only a small number of connectors and components critical to independent engine operation.


Located in in the main engine bay fuse box this is the link between the engine specific wiring and the power supply, fuses and relays to control engine ancillary devices.

C90 C200 & C809

C200 – Located on the drivers side, below the steering column.

C809 – Located on the back of the instrument cluster.


C391 & C456