Chrysler Full-Size Vans 1989-1998 Repair Guide

Engine Control Module

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OPERATION



See Figures 1, 2 and 3

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: Typical engine control schematic for an engine with Throttle Body Fuel Injection (TBI)



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Fig. Fig. 2: Typical engine control schematic for an engine with Multi-port Fuel Injection (MFI)



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Fig. Fig. 3: The ECM is located on the cowl in the engine compartment

REMOVAL & INSTALLATION



See Figures 4, 5, 6 and 7


WARNING
The negative battery cable MUST BE DISCONNECTED prior to servicing the ECM. Voltage spikes could damage the ECM while handling it.

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the retaining tabs on the cover over the ECM and remove the ECM cover.
  4.  
  5. Remove the ECM wiring harness connector(s).
  6.  
  7. Remove the ECM retaining bolts and remove the ECM.
  8.  

To install:
  1. Install the ECM and tighten mounting bolts to 35 inch lbs. (4 Nm).
  2.  
  3. Inspect the ECM pins and the terminals on the harness connector(s) for damage and corrosion before installing. Install wiring harness connector(s) onto ECM.
  4.  
  5. Install the ECM cover.
  6.  
  7. Connect the negative battery cable.
  8.  

If replacing the ECM on 1996-98 vehicles, the DRB-II scan tool or equivalent must be used to program the new processor with the vehicle's VIN number and original mileage. If this step is not done, a DTC can be set.

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Fig. Fig. 4: The ECM with its connector and cover removed



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Fig. Fig. 5: Handle the ECM with care after removal from the vehicle; dropping it could destroy the circuits inside



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Fig. Fig. 6: The ECM connector on 1989-95 vehicles is secured by a bolt



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Fig. Fig. 7: The ECM connector on 1996-98 vehicles is locked by a retaining tab that must be depressed for removal

 
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