Powertrain Controls - ECM/PCM

Diagnostic Chart:

Wiring Diagram:

CIRCUIT DESCRIPTION
CKT 439 is the ignition voltage feed for the PCM. CKT 440 is the battery feed for the PCM.

DTC 75 WILL SET WHEN
^ The ignition is "ON."
^ Ignition feed voltage to the control module is less than the graduated scale of:
- -40°C (-40°F) 7.3 volts.
- 90°C (194°F) 10.3 volts.
- 150°C (304°F) = 11.7 volts.
^ Engine speed greater than 1000 RPM.
^ All conditions met for 4 seconds.

ACTION TAKEN (PCM WILL DEFAULT TO)
^ No Torque Converter Clutch (TCC).
^ Maximum line pressure.
^ Soft landing to default gear.

DTC 75 WILL CLEAR WHEN
The fault condition(s) no longer exist.

DTC CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.
1. This test checks for normal battery voltage between 9-15 volts.
2. This test checks if the low voltage display is due to the generator, CKT 439 or PCM, with engine operating checks voltage at the battery. If the voltage is less than 8.6 volts, the PCM is OK.

DIAGNOSTIC AIDS
Charging battery with a battery charger and jump-starting engine may set DTC 53. If DTC sets when an accessory is operated, check for poor connections or excessive current draw. Refer to Charging System for circuit details. Also, check for poor connections at starter solenoid or fusible link.
^ 4L60K transmission default gear is 3rd.
^ 4L80E transmission default gear is 2nd.