P2784-INPUT SPEED SENSOR 1/2 CORRELATION

For a complete wiring diagram Refer to Section 8W

Theory of Operation

The Input Speed Sensors 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:
Engine speed greater than 450 RPM, no engine speed DTCs, no TCM undervoltage system operation, no output speed sensor DTCs (CAN signal from the ABS system), all wheel speeds above 250 RPM (CAN signal from the ABS system), no rear wheel speed 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:
If the speed difference between the Input Speed Sensors 1 and 2 (N2 - N3) is greater than 150 RPM.

Possible Causes

INTERNAL TRANSMISSION

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 FOR SPEED SENSOR OR SENSOR SUPPLY VOLTAGE DTCS

Are any Input Speed Sensor and/or Sensor Supply Voltage DTCs present?

Yes

Refer to the symptom list and perform the appropriate symptom(s).

Go To 2

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 located in 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.

Did the DTC P2784-INPUT SPEED SENSOR 1/2 CORRELATION reset?

Yes

Go To 3

Go To 4

3.INTERNAL TRANSMISSION

Is there any debris, plugged Transmission Oil Filter, or any sign of an internal transmission problem?

Yes

Repair as necessary. Refer to 21- AUTOMATIC - NAG1 for the appropriate service procedure(s).
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)

4.INTERMITTENT WIRING AND CONNECTORS

Were there any problems found?

Yes

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

Test Complete.