Case IH 12 – Electronic Instrument Cluster (EIC) / Instrument Control Unit (ICU): Coolant temperature sender open circuit or shorted to a +Ve voltage.

The control module is receiving a voltage signal from the engine coolant temperature sender that is out of the expected range, typically caused by a broken wire, an unplugged connector, a failed sensor, or a short to a power source.

• MXM
• Case IH MXM Series (MXM120, MXM130, MXM140, MXM155, MXM175, MXM190)
• Case IH Magnum Series
• Case IH Steiger Series
• Case IH Farmall Series
• Case IH CX Series (CX100)
• Case IH MX-C Series (MX100C)
• Case IH Older Magnum Series (7110, 7240, 8950)

1. 1

   Inspect connector C012 at the coolant temperature sender. Check if the terminal and connector are clean, free of corrosion, and fit together firmly.

2. 2

   With the connector removed, measure the resistance between the sender terminal and a good body ground (the engine block). Depending on the specific engine model, a good sender should read between 80Ω (hot) and 800Ω (cold), or 650Ω (hot) and 6000Ω (cold).

3. 3

   If the resistance is within spec, check if the sender has a poor ground contact with the engine block.

4. 4

   If the sensor tests good, disconnect the Instrument Cluster connector (C079). Test the signal wire between the cluster and the sender for an open circuit or a short to a 12V power source.

1. 1

   Resolve Connection Issues

   If connector C012 is loose or dirty, clean the contacts with electrical contact cleaner, apply dielectric grease, and reconnect firmly.

2. 2

   Fix Poor Grounding

   If the sender tested fine but lacks a ground, remove the sender, clean the thread contact area on both the sender and the engine block port with a wire brush, and reinstall it.

3. 3

   Replace the Sender

   If the sender failed the resistance test, drain the coolant below the level of the sensor port. Remove the old sender, install the new OEM replacement, and top off the coolant.

4. 4

   Repair the Harness

   If an open circuit or short was found in the wiring harness during diagnostics, trace the wire from the EIC to the engine block, locate the chafe or break, and splice/repair the wire.

5. 5

   Clear the Code

   Once the physical repair is complete, use the instrument cluster's diagnostic menu (or the Case IH Electronic Service Tool) to clear the fault code and run the tractor to verify normal operation.