How to Replace the ECM on Vehicles

by Contributing WriterUpdated June 12, 2017

The engine control module, which is also called the powertrain control module, is a Vehicles computer that controls many of the Vehicles functions. In most versions of the Vehicles the ECM is mounted in between the battery and the nearest headlight within the engine compartment. This can vary depending on the year of the van and the type of module it uses. You need to replace a malfunctioning module, and it may still require services from a technician to reset certain areas like the mileage.

Under The Hood:

 How to Replace the ECM on a 2004 Ford Taurus

Disconnect the negative battery cable from the battery terminal with the socket set.

Open the door to the glove box and remove everything from inside it.

Remove the screws that secure the front of the glove box to the bottom of the dash with a Phillips screwdriver.

Pull the glove box down from the dash until you can see the socket for the glove box light bulb. Pull the socket out of the glove box and then pull the glove box all the way to the floor of the Taurus.

Locate the silver box behind the glove box. The box has a wiring harness with approximately 100 wires connected to it. The box is silver with a long white product sticker on it. This is the ECM.

Pull the locks on each side of the wiring harness up and then pull the harness off the ECM.

Remove the four bolts that secure the ECM to the firewall with a socket and ratchet and remove the ECM from the Taurus.

Place the new ECM against the firewall and secure it using the four bolts and socket set.

Plug the wiring harness into the side of the ECM and push down on the locks to secure it into place.

Reconnect the bulb socket to the top of the glove box and position the glove box against the bottom of the dash. Secure it using the screws and screwdriver.

Reconnect the negative battery cable to the battery terminal.

Items you will need

  • Socket set

  • Phillips screwdriver

  • New ECM

 How to Replace the ECM on a 2005 Toyota Corolla


Document the VIN number that is viewable at the bottom of the windshield on the driver side of the vehicle. Turn the ignition key to the β€œOn” position and document the mileage on the odometer. Turn the ignition key off.

Lift the vehicle hood and support it with the hood prop rod. Loosen the negative battery terminal with the socket and ratchet. Disconnect the negative battery cable from the negative battery terminal.

Enter the passenger side of the vehicle and open the glove compartment drawer. Locate the drawer stoppers -- there is one on each side of the drawer. Remove the screw for each door stopper. Carefully squeeze on the sides of the drawer at the very back while pulling out on the drawer to release the upper drawer stoppers. Lift the drawer up to remove it from the dashboard.

Remove the two clips for the ECM cover with the flat-head screwdriver. Remove the cover from under the dashboard. Pop open the ECM wiring harness clamp with the flat-head screwdriver and disconnect all four ECM wiring harness connectors from the ECM.

Remove both bolts that secure the ECM brackets to the underside of the dashboard with the socket and ratchet. Locate the rear mounting clip. Squeeze the tongs on the back of the clip and push the clip through the mounting hole. Unfasten the mounting claw at the front of the ECM and lower the ECM and bracket assembly from under the dashboard.

Remove the screws for the ECM brackets with the socket and ratchet. Remove the brackets from the ECM. Compare the ECM that has been removed from the vehicle with the replacement. If the original ECM was manufactured by DENSO it must be replaced with a DENSO unit. If the original unit was manufactured by DELCO, it must be replaced with DELCO.

Take the replacement ECM to a Toyota dealership or local parts store along with the VIN number and mileage for flashing.


Install the ECM brackets onto the replacement ECM and tighten the mounting screws to 28 inch-pounds with the inch-pounds torque wrench.

Lift the ECM into position under the dashboard and push the rear mounting clip through the mounting hole. Fasten the front mounting claw connector. Install the ECM bracket to dash mounting bolts and tighten to 27 inch-pounds with the inch-pounds torque wrench.

Plug each plug into its terminal on the ECM; they will click when properly installed. Set the wiring harness into the harness clamp and lock the clamp closed to secure the harness.

Lift the ECM protective cover into position and install the retaining clips. Set the glove box drawer into position. Squeeze the upper sides of the drawer so that the upper stops will clear the opening in the dashboard and push the drawer back into the hole. Line up the lower stops to the mounting holes on each side of the drawer and install the lower stop mounting screws. Close the glove box drawer.

Install the negative battery cable to the negative post on the battery. Tighten the negative battery terminal with the socket and ratchet. Shut the hood.

Items you will need

  • Pen and paper

  • Screwdriver set

  • Socket and ratchet

  • Inch-pounds torque wrench

 How to Replace the ECM on a Lincoln Mark VIII

Open the Lincoln Mark VIII's hood by hand and support it on the prop rod if your model year does not have hood struts. Disconnect the Mark VIII's negative battery cable at the battery using the battery wrench.

Push the vehicle harness retaining clips off the harness connectors where they meet the ECM. The ECM is a steel box that mounts by the firewall, just below the cowl on the passenger side.

Pull the vehicle harness out of the back of the ECM by hand. Push the wiring harness away from the ECM so you can have access to the ECM mounting bolts.

Remove the ECM mounting bolts using the socket set. Lift the old ECM out of the Mark VIII's ECM bracket in the engine well, and set the new ECM into the ECM bracket.

Plug the wiring harness into the back of the new ECM. Close the vehicle harness retaining clips down over the harness connector to ensure the connector does not vibrate loose during vehicle operation.

Reconnect the Mark VIII's negative battery cable with the battery wrench. Shut the Mark VIII's hood.

Items you will need

  • Battery wrench

  • Socket set

 How to Replace the ECM for a 1999 S-10

Lift the hood and disconnect the negative battery terminal using a wrench. Move the terminal away from the battery to prevent it accidentally touching the battery terminal. Allow 20 minutes for the static electricity to dissipate before beginning.

Remove the nuts on both sides of the computer bracket using a 10 mm socket. Pull the computer out of its support bracket. Pull all three electrical plugs out of the computer. Remove the computer.

Remove the cover from the top rear of the computer using a socket. Do the same to the new computer. Release the two clips on the sides of the computer prom (memory chip) that is directly under the cover. Very carefully pull the prom up a small amount on one side and then lift it straight up out of the computer.

Ground yourself against the vehicle to dissipate any static electricity that could potentially damage the computer. Install the prom into the new computer, making absolutely sure that it is inserted properly so the terminals are not bent in the process. Raise the side clips and snap them in place on the prom.

Install the top cover. Push the three electrical plugs into the computer. Install the new computer and tighten the two nuts securing it to the bracket. Install the negative battery terminal on the battery and tighten with a wrench.

Items you will need

  • Ratchet

  • Set of sockets

  • Set of wrenches

 How to Replace the ECM in a Dodge Caravan

Disconnect the battery at its negative terminal, loosening the clamp nut for the black battery cable with a wrench, then disconnect the positive cable. Pull the heat shield off the battery.

Remove the ECM's upper bracket mounting bolts with a wrench and disconnect the electrical connectors.

Unscrew and remove the bolts for the headlight housing near the battery and ECM, pull the housing out and disconnect the electrical connectors for all of the headlight bulbs.

Remove the lower mounting bolt for the module and remove it from the van's engine compartment. Hold the module by the body without touching its terminals to avoid static shock.

Install the replacement control module and connect its lower and upper bolts and electrical connectors.

Reinstall the headlight housing with its electrical connectors and retaining bolts.

Slip the heat shield back onto the battery.

Reconnect the battery, starting with the positive cable and then the negative one.

Items you will need

  • Wrench

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