DTC Confirmation Test (Overall Function Check)

NOTE: Use the following test to check overall function of A/T control circuits. During this test, DTC may not be confirmed.

A/T control circuits are used to control shifting during hard acceleration or deceleration. Malfunction is detected when ECM receives incorrect voltage from Transmission Control Module (TCM) continuously. Only possible cause is an open or short in circuit between ECM and TCM.

To check overall function of A/T control circuits, start engine. Measure voltage between ground and ECM terminals No. 24 and 29 by backprobing. See Figure. Voltage should be about 7 volts.