John Deere 158.03 – Cab Module (CAB) or Armrest Interface Control (AIC): Switched Supply Voltage High

Triggered when the control unit registers that the switched supply voltage being delivered to the module has exceeded the acceptable upper limit, specifically over 16.0 volts.

• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 6230R
• 6250R
• 6090MC
• 6100MC
• 6110MC
• 6090RC
• 6100RC
• 6110RC
• 8245R
• 8270R
• 8295R
• 8320R
• 8335R
• 8345R
• 8400R
• 8130
• 8230
• 8330
• 8430
• 8530
• 331G Compact Track Loader
• 333G Compact Track Loader
• 744K Loader
• 245GLC Excavator
• 848H Skidder

1. 1

   Visually inspect the batteries and alternator for physical damage, loose connections, or accumulated debris.

2. 2

   Check the alternator cable and battery cables for corrosion, wear, or improper connections.

3. 3

   Use a multimeter to verify the electrical voltage at the battery terminals and at the module's power supply terminals (e.g., terminal F8 or the module harness).

4. 4

   Measure the voltage while the engine is running above 1500 RPM. If the voltage is consistently above 16.0V, the alternator's voltage regulator is likely overcharging the system.

1. 1

   Power Down

   Turn off the engine and disconnect the battery to ensure safety while working on the electrical system.

2. 2

   Inspect and Clean

   Clean any debris from the alternator and battery terminals. Ensure all grounding points to the chassis are secure and free of corrosion.

3. 3

   Test the Alternator/Regulator

   If the multimeter confirmed an output of >16V while the engine was running, the voltage regulator (often internal to the alternator) has failed.

4. 4

   Replace Faulty Component

   Replace the faulty voltage regulator or the entire alternator assembly.

5. 5

   Check Wiring

   Inspect the wiring harness leading to the AIC or CAB module for any shorts to power that could be artificially raising the voltage reading at the module.

6. 6

   Reassemble and Clear Codes

   Reconnect the battery, start the vehicle, and cycle the monitor/controls. If the voltage is now within the normal range (typically 13.5V - 14.5V), clear the code. If the code returns, contact a John Deere dealer for further module testing.