Description

This TSB has been revised to include the 1992-1994 Excel and 1992 Scoups.

Some 1990 & 1991 Excel and 1991 Scoupe models may experience recurrent activation of the "Check Engine" light and setting of fault code 15 in the engine control module (ECM) memory. The vehicle may exhibit stalling at idle and an inoperative air conditioning compressor when this condition occurs.

These symptoms may be related to a poor throttle position (TP) sensor ground circuit in the ECM wiring harness. The field fix procedure for this condition varies according to the wiring harness manufacturer, but basically involves the soldering of a crimp connection.

The connection involved is located where four black ground wires (five in California specification cars) for the throttle position (TP) sensor, idle speed control (ISC) motor position sensor, volume airflow (VAF) sensor, and engine coolant temperature (ECT) sensor (plus the EGR temperature sensor on California spec. vehicles) are joined with two ground wires leading to the ECM. (See splice SCO8 on page 23-3 of the 1990-1992 Excel Electrical Troubleshooting Manual, or splice SCO3 on page 23-3 of the 1991-1992 Scoupe Electrical Troubleshooting Manual.)