P1705-INPUT SPEED SENSOR 2 OVERSPEED

For a complete wiring diagram Refer to Section 8W

Theory of Operation

The NAG1 transmission has two input speed sensors 1 and 2 (N2 and N3), both speed sensors are located on the valve body. The speed sensors are hall effect speed sensors that are used by the Transmission Control Module (TCM) to calculate the transmissions input speed. Since the input speed could not be measured directly, two of the drive elements are measured. Two input speed sensors were required because both drive elements are not active in all gears.

The input speed sensors 1 and 2 will report the same input speed in gears 2nd, 3rd or 4th. If the 1 and 2 input speed sensor signals are not the same in these gears, the TCM will set the DTC P2784-Input Speed Sensor 1/2 Correlation. The input speed sensor 2 is not reported in 1st and 5th gears. The input speed sensor 1 (N2) is not reported in Reverse. The P01704-Input Speed Sensor 1 Overspeed and P01705-Input Speed Sensor 2 Overspeed DTCs are rationality checks designed to detect a major transmission failure. If either DTC is detected, the TCM will place the transmission in Neutral.

• When Monitored:

  Continuously with the ignition on, engine running, transmission in gear, and Input Speed Sensor 2 (N3) greater than 0 RPM

• Set Condition:

  If the RPM of the Input Speed Sensor 2 (N3) is greater than 7700 RPM.

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

Diagnostic Test

WARNING: To avoid personal injury or death, keep hands and feet clear of rotating wheels.

• Go To 2

• Go To 3

• Repair internal transmission as necessary. Refer to 21- AUTOMATIC TRANSMISSION-AUTOMATIC TRANSMISSION NAG1/SERVICE INFORMATION for the appropriate service procedure.
• Perform NAG1 TRANSMISSION VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - NAG1 - STANDARD PROCEDURE)

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

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

• Test Complete.