Ecu Replacement/Wiring Modification (18-52-88)

ECU REMOVAL

The ECU is located in a plastic clamshell that is mounted under the black plastic cover (B) on the left inner strut tower in the engine compartment. See Fig 1.

1. Disconnect the battery negative cable.
2. Remove the wing nut (A). See Fig 1.
3. Remove the black plastic cover (B). See Fig 1.
4. Pull back retaining clip.
5. Remove and open the plastic clamshell.
6. Disconnect the E W connector.
7. Remove the ECU-retaining nuts and remove the ECU from the clamshell.

Fig 1: Wing Nut & Black Plastic Cover

WIRING MODIFICATION

1. Locate the B+ latch relay (D) and the fuel pump relay (C), which are mounted on the inside of the upper half of the ECU housing. See Fig 2. The B+ latch relay has only small diameter wires attached to the connector. The fuel pump relay has two large diameter (10 gauge wires attached to its connector.
2. Remove the connector from the B+ latch relay.
3. Cut the yellow w/trace wire (E) approximately 12 inches back from B+ latch relay connector. Strip 2 inch of insulation from both ends of the cut wire. See Fig 3.
   Fig 2: B+ Latch Relay & Fuel Pump Relay

   
4. Cut the small (20 gauge) brown wire (F) 2 inch from the B+ latch relay connector and carefully tape the connector end of the cut wire. Strip 2 inch of insulation from the harness end of the cut wire. See Fig 3.
   Fig 3: Location of Wires to Cut

   
5. Hold the harness end of the brown wire (F) parallel to the yellow w/trace wire (E), and slide 12 inches of heat shrink tubing (G) over the ends and down the wires about 2 inches to avoid damage during the soldering process. See Fig 4.
   Fig 4: Connecting Cut Wires

   
6. Twist the end of the brown wire (F) and the two ends of the previously cut yellow w/trace wire (E) together tightly. See Fig 4.
7. Solder the twisted ends with resin core solder, See Fig 5. Carefully fold down the soldered joint onto the wires after the joint has cooled.
   Fig 5: Soldering Wires

   
8. Slide the heat shrink tubing over the soldered joint and shrink the tubing with a heat gun (H). See Fig 6.
   Fig 6: Heating Shrink Tubing

   
9. Reinstall the connector to the B+ latch relay.

ECU INSTALLATION

1. Position the new ECU (PN T0741580) into the clamshell and install the retaining nuts.
2. Connect the ECU connector.
3. Place the top half of the clamshell on the bottom half and secure the assembly in position with the retaining clip.
4. Verify if the vehicle is equipped with the Oxygen Sensor Module kit. See Fig 7.

Fig 7: Oxygen Sensor Module Kit

The module will be mounted on the right-hand headlight panel as shown in Fig 8.

If the vehicle is equipped with the Oxygen Sensor Module Kit, THE KIT MUST BE REMOVED  before completing the ECU installation. Refer to next section entitled, "OXYGEN SENSOR MODEL KIT REMOVAL". If the vehicle is not equipped with the Oxygen Sensor Module Kit complete the following steps 5 and 6.

1. Position the black plastic cover and secure with wing nut.
2. Connect the battery negative cable.

OXYGEN SENSOR MODULE KIT REMOVAL

1. Remove the Oxygen Sensor Module (A) and ground wire eyelet (B) mounted on the right-hand headlight panel. See Fig 8 .
   Fig 8: Oxygen Sensor Module & Ground Eyelet

   
2. Disconnect the wiring harness between Oxygen Sensor connectors (C) and (D). Set aside the two ends that are connected directly to the Oxygen Sensor Module. See Fig 9.
   Fig 9: Location of Oxygen Sensor Connectors

   
3. Connect the two remaining ends and install in the retainer clip (H) on the engine block. See Fig 10.
   Fig 10: Retaining Clip Installation

   
4. Remove the plastic ties holding the voltage source wire (E) to the radiator upper crossmember. See Fig 11.
   Fig 11: Location of Plastic Ties

   
5. Locate the green wire [mounted on the ECU clamshell, (N)] leading to terminal "C" of the map sensor connector (M). See Fig 12.
   Fig 12: View of Map Sensor Connector

   
6. Remove the heat shrink tubing that is covering a connection approximately 12 inches from the connector.
7. Unsolder the voltage source wire (E) and remove from the green map sensor feed wires. Discard the Oxygen Sensor Module Kit. See Fig 11.
8. Slide a length of heat shrink tubing over the green wire.
9. Resolder the two ends of the green wire together.
10. Slide the heat shrink tubing over the soldered connection, being sure that the tubing completely covers the soldered joint and any section of bare wires.
11. Shrink the tubing with a heat gun.
12. Position the ECU black plastic cover and secure with wing nut.
13. Connect the battery negative cable.