P2784 Input speed sensor 1/2 correlation

P2784 code - The input speed 1 and 2 (N2 -N3) will report the same speed in 2nd, 3rd and 4th gears. If the input speed sensor 1 and 2 signals are not the same in these gears, the DTC will set.

When monitored this DTC the Engine speed greater than 450 rpm, no speed DTCs, no TCM undervoltage system operation, no output speed sensor DTCs signal from the ABS system, and no wheel slip detected CAN signal from the ABS system, no shifting operation, input speed sensor 2 N3 greater than 800 rpm and input speed sensor 1 N2 greater than 0 rpm and the TCM not in reset. Set condition this DTC If the speed difference between the input speed sensor 1 and 2 (N2-N3) is greater than 150 rpm. 

Possible causes P2784 code:

- Internal transmission 

- Transmission control module (TCM)

Diagnostic test P2784 code

Step 1. Check for speed sensor or sensor supply voltage DTCs

Whith the scan tool, check for other transmission DTCs.

Are any input speed sensor and or sensor supply voltage DTCs present?

Yes, refer to transmssion control module (TCM) diagnosis and testing, and perform the appropriate diagnostic procedure.

No, go to step 2.

Step 2. Check to see if input sensor mismatch is current

Note: If the TCM detects and stores a DTC, the TCM also stores the vehicles operating conditions under which the DTC originally set and is scan tool under environmental data. Before erasing any stored DTCs, record any available data to assist in duplicating the conditions in which the DTC originally set. 

With the scan tool, record the environmental data and erase transmission DTCs. Using the environmental data recorded earlier, test drive the vehicle while trying to duplicate the conditions which the DTC originally.

Did the DTC P2784 Input speed sensor 1/2 correlation reset?

Yes, go to step 3.

No, go to step 4.

Step 3. Internal transmission 

Turn the ignition off to the lock position. Remove the transmission oil pan inspect for debris, a plugged transmission oil filter, or any sign of an internal transmission problem.

Is there any debris, plugged transmission oil filter, or any sign of an internal transmission problem?

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

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

Step 4. 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 spesific to this circuit. Wiggle the wiring and connectors while checking for any possible open or shorted circuits. Perform any service information tune-ups 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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