Case IH 2093 – CCU (Central Control Unit / Chassis Control Unit): Low power HSD (cn1-5) short to +12VF

The High Side Driver (HSD) circuit for the Left Turn Signal Indicator is shorted to +12 Volts Fused (battery voltage). The system has detected that the circuit connected at connector CN1, pin 5 is receiving 12V when it shouldn't be, indicating a short to power.

• Farmall
• Puma 140
• Puma 150
• Puma 165
• Puma 180
• Puma 185
• Puma 195
• Puma 210
• Puma 225
• Puma 240 CVX

1. 1

   Perform a Switch Operation Test (H5 Menu) by depressing the 'dimming' button; activate the left turn signal and check for code 'd70', performing a wiggle test if not displayed.

2. 2

   Inspect the wiring harness from the CCU (Connector CN1, Pin 5) to the left turn signal indicator light for rubbed-through insulation touching a 12V power source.

3. 3

   Check the turn signal switch/stalk on the steering column and the left turn signal bulb sockets for internal shorts or melted contacts bridging to a 12V wire.

1. 1

   Disconnect Power

   Turn off the tractor and disconnect the battery to prevent further electrical damage.

2. 2

   Test the Circuit

   Access the CCU and disconnect connector CN1. Use a digital multimeter to measure voltage on pin 5 of the harness side. Reconnect the battery temporarily; if 12V is present with the turn signal switch in the 'off' position, there is a hard short to power in the harness or switch.

3. 3

   Isolate the Switch

   Disconnect the steering column turn signal switch. If the 12V short on CN1-5 disappears, the turn signal switch assembly is internally shorted and must be replaced.

4. 4

   Repair Wiring

   If the switch is fine, trace the wire from CN1-5 to the left turn signal indicator. Repair any damaged wiring or replace shorted bulb sockets.

5. 5

   Clear Stored Codes (H8 Menu)

   Once the repair is made, reconnect all components and the battery. Access the H8 Menu (Clear stored calibration information / EEPROM) on the instrument controller. This menu clears stored error codes by resetting EEPROM values back to default.