P1705 Input speed sensor 2 overspeed

P1705 code


P1705 codeThe NAG1 transmission has two input speed sensor 1 and 2 (N2 and N3), both speed sensors are located on the valve body. The speed 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 drive elements are measured. Two input sendor were required because both drive elements are not active in all gears. The input speed sensor 1-2 will report the same input speed in gears 2nd, 3rd, 4th. If the 1 an 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 P1704 input speed sensor 1 is over speed and P1705 input speed sensor 2 overspeed DTCs are rationality check designed to detect a major transmission failure. If either DTC is detected, the TCM will place transmission in neutral. When monitored this DTC countinuously with the ignition on, engine running, transmission in gear, and input speed senor 2 (N3) greater than 0 rpm. Set condition If the rpm of the input speed sensor 2 (N3) is greater than 7700 rpm.

Possible causes P1705 code:

- Internal transmission 

- transmission control module (TCM)

Diagnostic test P1705 code

Step 1. Check to see if DTC is current 

Turn the ignition on. With the scan tool, erase transmisson DTCs. Raise the vehicle on the hoist. Start the engine. With the scan tool, monitor the input speed sensor 2 rpm. Firmly apply the brakes and place the gear selector in drive.

To avoid possible serious or fatal injury, keep hands and feet clear of rotating wheels.

Release the brakes and raise the engine rpm to allow the transmission to upshift to the 2-3 and 3-4 shift schedule.

Did the input speed sensor 2 display an rpm above 7700?

Yes, go to step 2.

No, go to step 3.

Step 2. Internal transmission

This DTC is an indication of an internal transmission failure. Remove the transmission oil pan inspect for excessive debris such as clutch friction material or metal contamination.

Is there any indication of an internal transmission failure?

Yes, repair internal transmission as necessary in accordance with the service information. Perform NAG1 Transmission Verification Test. 

No, using the schematics as a guide, check the tansmission control module (TCM) terminals for corrosion, damage or terminals push out. Pay particular attention to all power and ground circuits. If no problems are found, replace the TCM in accordance with the service information. Perform NAG1 Transmission Verification Test. 

Step 3. Check the wiring and connectors

The conditions necessary to set this DTC are not present at this time. Using the schematics as a guide, inspect the wiring and connectors specific to this circuit. Wiggle the wiring and connectors while checking for any possible open or shorted circuits. Check for any service information tune up or technical service bulletins that may apply.

Were there any problems found ? 

Yes, repair as necessary. Perform NAG1 Transmission Verification Test. 

No, test complete.

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