Case IH 2620 – ZTC: Transmission Input Shaft Speed Sensor Short to Ground

The Transmission Input Shaft Speed Sensor circuit is shorted to ground. The control module is detecting 0 volts or a direct path to chassis ground on the sensor's signal or power circuit, preventing it from reading the rotational speed of the transmission input shaft.

• Steiger T4B
• Case IH Steiger AFS Connect series
• Case IH Quadtrac series (e.g., 535)
• Case IH Puma CVX (170, 185, 200, 215, 230)
• Case IH Optum CVX (270, 300)
• Case IH Maxxum series

1. 1

   Visually inspect the sensor connection and wiring harness for visible damage, chafing, or pinched wires that could cause a short to ground

2. 2

   Perform a resistance test on the disconnected sensor using a multimeter (a healthy sensor reads around 3,000 ohms; 0 ohms indicates an internal short)

3. 3

   Test the harness-side signal wire for continuity to ground with the sensor disconnected to check for a shorted wiring harness

4. 4

   Hook up the Case IH Electronic Service Tool (EST) and monitor the input shaft speed sensor (usually designated as Sensor 1)

1. 1

   Power down and disconnect battery

   Power down the tractor and disconnect the battery to prevent electrical spikes.

2. 2

   Locate sensor

   Locate the transmission input shaft speed sensor on the transmission housing. On heavy models like the Quadtrac, it is typically located on the transmission housing and identified as Sensor 1.

3. 3

   Disconnect connector

   Disconnect the electrical connector (identified in parts catalogs as Connector X-513).

4. 4

   Repair harness or proceed to sensor replacement

   If the diagnostic checks pointed to a harness issue, repair the shorted wire in the loom. If the sensor failed the resistance test, proceed to step 5.

5. 5

   Remove faulty sensor

   Unscrew and remove the faulty speed sensor from the transmission housing.

6. 6

   Install new sensor

   Install the new sensor. Screw the sensor in by hand until the sensor tip lightly contacts the internal gear, then back it off slightly or tighten it to the specific model's torque specification to set the air gap.

7. 7

   Reconnect connector

   Reconnect the X-513 electrical connector.

8. 8

   Clear codes and verify

   Reconnect the battery, start the machine, and use the Electronic Service Tool (EST) to clear the fault codes and verify that the input shaft speed is reading correctly.