Engine Control Module: Testing and Inspection

Warped Connectors:

***UPDATED BY TSB #EF91002 DATED MAY 1991
Some models may fail to start if the ECU connector is not fully seated. The connector may be cocked to one side or misaligned with the center bolt tightened due to the plastic encasement on the ECU or the electrical connector itself being warped.

Connector Clearance:

When installing the connector, secure it firmly by hand before tightening the bolt. When properly seated the top of the connector should not extend more than 7mm beyond the ECU case as shown in Fig. 2. The center bolt can be tightened without the connection being installed properly.

Fig. 3 Red Button:

On some models, a red plastic button will show when the connector is properly installed. Refer to Fig. 3.

WARNING: When probing terminals, be careful not to short wires together. Also do not bend or loosen terminals. This could result in irreparable damage to the ECU and/or wiring harness.
1. Disconnect battery ground cable.
2. Access ECU from the R.F. kick panel.
3. Disconnect connectors from the ECU.
4. Reconnect the connectors to the ECU.
5. Reconnect the battery ground cable.
6. Measure the voltage at the given terminals as per the chart.
7. Perform all Voltage tests with the connectors Connected.
8. Perform all Resistance tests with the connectors Disconnected.
9. Be certain there are no breaks or bends in the ECU pins prior to reading measurements.

ECM Terminal Layout:

ECU TERMINAL LAYOUT

6;Fn;ECU Terminal Reference:

ECU PIN VOLTAGES