John Deere 002876.02 – CAB: Turn Signal Switch Input Signal Fault

The Cab Control Unit (CAB) has detected an erratic, intermittent, or incorrect signal from the turn signal switch circuit. This indicates the system is receiving illogical inputs, such as simultaneous left and right turn signals or an intermittent loss of signal, pointing to a fault within the turn signal switch itself, the connecting wiring, or the turn signal controller/flasher module.

• 1050
• 1070
• 2140
• 2150
• 2155
• 2255
• 2350
• 2355
• 2550
• 2555
• 2750
• 2755
• 2950
• 2955
• 3040
• 3140
• 3150
• 3155
• 3255
• 4050
• 4200
• 4210
• 4250
• 4300
• 4310
• 4400
• 4410
• 4450
• 4500
• 4510
• 4600
• 4610
• 4650
• 4700
• 4710
• 4850
• 5075E
• 5103
• 5105
• 5200
• 5203
• 5204
• 5205
• 5210
• 5220
• 5225
• 5300
• 5303
• 5310
• 5320
• 5325
• 5400
• 5403
• 5410
• 5415
• 5420
• 5425
• 5500
• 5503
• 5510
• 5520
• 5525
• 5600
• 5603
• 5605
• 5615
• 5625
• 5700
• 5705
• 5715
• 5720
• 6403
• 6603
• 7020
• 7520
• 7720
• 8430
• 8440
• 8450
• 8630
• 8640
• 8650
• 8850
• 110 TLB
• 650
• 670
• 770
• 790
• 850
• 870
• 950
• 970
• 990
• 6620
• 8820
• 7455
• 9935
• 9970
• 9976

1. 1

   Visually inspect the turn signal switch, wiring harness, and connectors for chafed or melted wires, loose connections, corrosion, or rodent damage.

2. 2

   Check the ground wire for the turn signal switch and the cab control unit to ensure the connection is clean, tight, and free of corrosion.

3. 3

   Access the diagnostic addresses in the tractor's monitor (e.g., BCU 19) to perform a Turn Signal Switch Circuit Test and verify switch status inputs.

4. 4

   Perform a voltage test at the switch connector to ensure power input is present with the key ON, and verify correct voltage output for left and right signals without simultaneous voltage on both.

5. 5

   Disconnect the battery and switch connector to perform a continuity test between the power input pin and the left/right output pins, ensuring no continuity exists between the left and right output pins.

1. 1

   Ensure safety

   Park the machine on a level surface, lower all implements to the ground, shut off the engine, and remove the key. For any electrical work, it is recommended to disconnect the battery's negative terminal.

2. 2

   Access the component

   Remove dash panels as needed to gain access to the back of the turn signal switch or the turn signal control module. On many tractors, this involves removing screws from the side and front dash panels.

3. 3

   Perform diagnostic checks

   Follow the diagnostic steps listed above to confirm the point of failure. Common failures are the switch itself or the separate turn signal controller/flasher module.

4. 4

   Replace turn signal switch

   If the turn signal switch is identified as the fault, disconnect its electrical connector and remove it from the steering column or dash. Install the new switch, reconnect the wiring, and reassemble the dash panels.

5. 5

   Replace turn signal controller module

   If the machine uses a separate turn signal controller module (often a small box with relays under the dash), and the switch tests good, this module is the next likely culprit. Disconnect the old module and replace it with the new part.

6. 6

   Final test

   Reconnect the battery if it was disconnected. Turn the ignition key to the "ON" position and test the functionality of the left turn signal, right turn signal, and hazard lights.

7. 7

   Clear fault codes

   After confirming the repair, use the tractor's diagnostic display to clear the stored fault codes. Operate the machine and re-check for any active codes to ensure the problem is fully resolved.