Volvo 240/740/760/780/940/960 1990-1998

Engine Control Module

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OPERATION



See Figures 1, 2, 3, 4, 5 and 6

The Engine Control Module (ECM) performs many functions on your vehicle. The module accepts information from various engine sensors and computes the required fuel flow rate necessary to maintain the correct amount of air/fuel ratio throughout the entire engine operational range.

Based on the information that is received and programmed into the ECM's memory, the ECM generates output signals to control relays, actuators and solenoids. The ECM also sends out a command to the fuel injectors that meters the appropriate quantity of fuel. The module automatically senses and compensates for any changes in altitude when driving your vehicle.



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Fig. Fig. 1: Regina Fuel Injection System



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Fig. Fig. 2: LH-Jetronic 2.4 and 3.1 Fuel Injection System



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Fig. Fig. 3: Motronic 1.8 Fuel Injection System



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Fig. Fig. 4: Bosch Lh-Jetronic 3.2 Fuel Injection System



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Fig. Fig. 5: Motronic 4.3 Fuel Injection System



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Fig. Fig. 6: Motronic 4.4 Fuel Injection Sytem

REMOVAL & INSTALLATION



If the battery cable(s) is disconnected for longer than 5 minutes, the adaptive fuel factor will be lost. After repair it will be necessary to drive the vehicle at least 10 miles, and as many as 250, to allow the processor to relearn the correct factors. The driving period should include steady-throttle open road driving if possible. During the drive, the vehicle may exhibit driveability symptoms not noticed before. These symptoms should clear as the control module computes the correction factor.

Coupe, 240, 700 and 940 Series

See Figure 7



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Fig. Fig. 7: Location of the ECM on Coupe, 240, 700 and 940 series models. Be sure to lift the retaining clip before detaching the connector

The ECM is located on the passenger side footwell under the kickpanel.

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the kickpanel to access the ECM.
  4.  
  5. Remove the retaining bolts on the ECM bracket.
  6.  
  7. Carefully lower the ECM and unlatch the harness connector from the ECM.
  8.  
  9. Remove the ECM.
  10.  

To install:
  1. Attach the connector to the ECM and carefully place it into position.
  2.  
  3. Tighten the bracket retaining bolts.
  4.  
  5. Install the kickpanel.
  6.  
  7. Connect the negative battery cable.
  8.  
  9. Start the vehicle and check to make sure the check engine light on the instrument cluster is operative.
  10.  

960/S90/V90 Series

See Figure 8



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Fig. Fig. 8: On 960/S90/V90 series vehicles, the ECM is located behind the drivers side dash panel

The ECM is located behind the drivers side of the dash panel, just beneath the steering column.

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the knee bolster panel under the steering column.
  4.  
  5. Remove the retaining bolts on the ECM bracket.
  6.  
  7. Carefully lower the ECM and unlatch the harness connector from the ECM.
  8.  
  9. Remove the ECM.
  10.  

To install:
  1. Attach the connector to the ECM and carefully place it into position.
  2.  
  3. Tighten the bracket retaining bolts.
  4.  
  5. Install the knee bolster panel.
  6.  
  7. Connect the negative battery cable.
  8.  
  9. Start the vehicle and check to make sure the check engine light on the instrument cluster is operative.
  10.  

850/C70/S70/V70 Series

See Figure 9

The ECM on these models is in the engine compartment in a box similar to the air cleaner box. Air is brought through a pick-up tube from under the car and used to cool the modules as the vehicle drives along. There are sometimes three modules located in this box: an Ignition Control Module (ICM), ECM and, on automatic transaxle vehicles only, a Transmission Control Module (TCM). The ECM is usually the center one.

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the lid on the module box behind the passenger side headlamp.
  4.  
  5. Reach down and unsnap the harness connector and remove the ECM from the box.
  6.  

To install:
  1. Place the ECM into the box and attach the harness connector to it.
  2.  
  3. Install the lid onto the module box.
  4.  
  5. Connect the negative battery cable.
  6.  
  7. Start the vehicle and check to make sure the check engine light on the instrument cluster is operative.
  8.  



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Fig. Fig. 9: The ECM and transmission module as located in the module box (with the lid removed)

 
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