John Deere CAB2876 – CAB: Turn Signal Switch Fault

The Cab Control Unit (CAB) has detected a turn signal switch fault where both the left and right turn signals are registered as being active at the same time. This typically indicates a short circuit in the wiring harness or an internal failure within the turn signal switch assembly itself.

• 9660 STS
• 9670 STS
• 9760 STS
• 9770 STS
• 9970 STS
• 6020
• 7630
• 7730
• 7830
• 7930
• 9230
• 9330
• 9430
• 9530
• 9630
• 5055E
• 5065E
• 5075E
• Gator utility vehicles
• compact tractors
• Gator XUV560E

1. 1

   Restart the vehicle to perform a power cycle, which can sometimes clear temporary communication glitches

2. 2

   Perform a functional check by operating the turn signal lever for both left and right turns, and activate the hazard lights to observe if both sides illuminate when only one is selected, or if there is no function at all

3. 3

   Inspect the wiring harness connected to the turn signal switch and the lights for chafed insulation, loose connections, corrosion, or shorts

4. 4

   Check fuses related to the lighting and cab control circuits to ensure none are blown

5. 5

   Access the onboard diagnostic system (e.g., CommandCenter) to view active and stored codes, confirming CAB 2876 is the primary issue

1. 1

   Disconnect power

   Disconnect the battery before beginning any electrical repair work to ensure safety.

2. 2

   Access the switch

   Remove the dashboard panels or steering column covers by removing the necessary retaining screws.

3. 3

   Remove switch handle

   Remove the screw securing the handle to the switch shaft. If the screw is seized, careful drilling may be required to remove it.

4. 4

   Unmount the switch

   Unscrew the retaining nut that holds the switch assembly to the dash or steering column.

5. 5

   Disconnect electrical connector

   Gently wiggle the electrical connector to release it from the switch. Exercise caution as the plastic on older connectors can be brittle.

6. 6

   Install new switch

   Connect the electrical connector to the new switch, mount it in place with the retaining nut, and re-install the handle.

7. 7

   Reassemble and test

   Re-install any panels that were removed and reconnect the battery. Test the functionality of the left turn, right turn, and hazard lights to ensure the fault is cleared.