John Deere 708.18 – Steering System Control Unit: Frequency on Channel 1 of Steering Input Device (SID) Too Low

Indicates a Steering System Control Unit Fault related to the Steering Input Device (SID) / Steering Wheel Position Sensor. The frequency on Channel 1 drops below the expected threshold, which often disables AutoTrac and can impair electronic steering response.

• 6110M
• 6120M
• 6130M
• 6145M
• 6155M
• 6175M
• 6195M
• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 8225R
• 8235R
• 8245R
• 8260R
• 8285R
• 8310R
• 8335R
• 8360R
• 8400R
• 9470RT
• 9520RT
• 9570RT
• 9420RX
• 9620R
• 7200R
• 7215R
• 7230R
• 7260R
• 7280R
• 6145J
• 6165J
• 6180J
• 3520
• CH570
• CH670

1. 1

   Sensor vs. Harness Isolation Test: Interchange the steering wheel position sensor connectors at the SID. Clear the codes and turn the steering wheel. If the same DTC returns, suspect a wiring harness issue. If a different DTC returns, the SID/sensor has failed internally.

2. 2

   Wiring Inspection: Inspect the Steering Input Device wiring harness for chafing, pin corrosion, or loose connections under the steering cowl.

3. 3

   Software Check: Verify the Steering Control Unit / BCU software is up to date. Reprogram with the latest software payload and run calibrations before condemning hard parts.

1. 1

   Power down machine

   Power down the machine and disconnect the battery to prevent accidental shorting.

2. 2

   Remove steering column covers

   Remove the steering column covers/cowl to access the steering wheel shaft and the Steering Input Device (SID).

3. 3

   Disconnect electrical connectors

   Disconnect the electrical connectors attached to the faulty Steering Wheel Position Sensor / SID.

4. 4

   Unbolt sensor bracket

   Unbolt the sensor bracket (e.g., Bracket HXE12978) or remove the retaining hardware securing the rotary sensor to the steering column.

5. 5

   Remove faulty sensor

   Remove the faulty sensor.

6. 6

   Install new sensor

   Install the new Steering Wheel Position Sensor / SID and secure the mounting hardware.

7. 7

   Reconnect wiring harness

   Reconnect the wiring harness connectors.

8. 8

   Reinstall steering column covers

   Reinstall the steering column covers/cowl.

9. 9

   Reconnect battery and clear codes

   Reconnect the battery, turn the key on, and clear the diagnostic trouble codes.

10. 10

    Perform steering system calibration

    Perform the steering system calibration/configuration via the John Deere Service ADVISOR tool as required by the specific machine's technical manual.