P0714-TRANSMISSION TEMPERATURE SENSOR INTERMITTENT

For a complete wiring diagram Refer to Section 8W

Theory of Operation

The Electrohydraulic Control Unit Assembly of the NAG1 transmission contains a temperature sensor to monitor the transmission oil temperature. This sensor is wired in series with the transmission Park/Neutral switch. The Transmission Control Module (TCM) expects to see a valid voltage level from the sensor when the shifter is in Reverse or any forward Drive position. The TCM also expects to see an open circuit condition when the shifter is in the Park or Neutral position. When the controller detects an open circuit when in Reverse or any forward drive position the DTC will set. Note: The TCM substitutes the Transmission Temperature reading with Engine Temperature due to a open circuit condition in Park or Neutral.

When Monitored:
Continuously with the ignition on and the Transmission Temperature below 170 °C (338 °F).
Set Condition:
When the TCM detects the Temperature sensor input changes more than 10 °C (18 °F) between each 20 mSec sensor read.

Possible Causes

WIRING AND CONNECTORS

TRANSMISSION TEMPERATURE SENSOR - P/N SWITCH

TRANSMISSION CONTROL MODULE

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - NAG1 - STANDARD PROCEDURE)

Diagnostic Test

1. CHECK WIRING AND CONNECTORS

Ignition on, engine not running.
With the scan tool, monitor the Transmission Temperature.
Apply the parking brake.
With the brakes firmly applied, place the gear selector in Drive.
While monitoring the scan tool, wiggle the wires and connectors from the TCM to the Electrohydraulic Control Unit.

Did the transmission temperature fluctuate while wiggling the wires?

Yes

Repair the wiring and/or connectors as necessary.

Perform NAG1 TRANSMISSION VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - NAG1 - STANDARD PROCEDURE)

Go To 2

2. CHECK IF DTC RESETS

Replace the Transmission Temperature Sensor per the Service Information.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - NAG1 - STANDARD PROCEDURE)
With the scan tool, read Transmission DTCs.

Did DTC P0714 reset?

Yes

Using the schematics as a guide, check the Transmission Control Module (TCM) pins, terminals, and connectors for corrosion, damage, or terminal push out. Pay particular attention to all power and ground circuits. If no problems are found, replace the TCM per the Service Information. Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES/TRANSMISSION CONTROL MODULE for the appropriate service procedure.
Perform NAG1 TRANSMISSION VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - NAG1 - STANDARD PROCEDURE)

Test Complete.