Powertrain Controls - ECM/PCM

DTC 68:

Overdrive Ratio Circuit:

CIRCUIT DESCRIPTION:
The PCM/TCM monitors the difference in engine rpm and input shaft rpm. With transmission in "drive," the "Scan" tool reading should show engine speed closely matching input speed.

TEST DESCRIPTION:
Number(s) below refer to circled number(s) on the diagnostic chart.

1. Code 68 will set if:
^ Engine speed is 200 rpm higher than input speed.
^ 4th gear is indicated.
^ TCC is enabled.
^ All conditions are met for 2 seconds.
^ Not in park or neutral.

2. This test monitors signal sent to the PCM/TCM from the transmission.

3. This test confirms engine rpm signal to PCM/TCM.

DIAGNOSTIC AIDS:
^ Check for deformed connectors at pass-thru connector.
^ Code 68 will set when going to default (2nd gear).
^ - Intermittent Malfunctions
^ Testing and Inspection