John Deere 000158.00 – RLC: Voltage To Cab Roof Module Exceeds 15.5 Volts

The voltage supplied to the Cab Roof Module (RLC) is higher than the acceptable limit of 15.5 volts. This high voltage condition indicates an issue with the power supply or voltage regulation, which can lead to malfunction or damage to the electronic components within the RLC. It is sometimes described generally as 'Regulated Voltage Above 18V' or a 'CAB switched power voltage problem'.

• 6R Series
• 6110R
• 6120R
• R-series

1. 1

   Verify battery and charging system voltage: with engine off, battery should read ~12.6V. With engine running at 1500 RPM, voltage should be 13.5-14.5V. Readings above 15.5V confirm an overcharging condition

2. 2

   Inspect the wiring harness leading to the alternator and the Cab Roof Module for frayed wires or cracked insulation

3. 3

   Check all connections to ensure they are clean, tight, and free of corrosion. A poor ground connection can cause the voltage regulator to misread system voltage

4. 4

   Inspect the alternator belt for proper tension and condition to rule out slipping

1. 1

   Disconnect battery

   Disconnect the negative battery cable before working on the electrical system for safety.

2. 2

   Repair wiring and grounds

   Repair or replace any damaged wiring or corroded connections found during inspection. Ensure all ground connections are secure to a clean, bare metal surface.

3. 3

   Test alternator

   If wiring and connections are in good condition, the issue likely lies with the alternator's internal voltage regulator.

4. 4

   Replace alternator

   If the internal voltage regulator has failed, replace the entire alternator assembly.

5. 5

   Reconnect and re-test

   Reconnect the battery, start the engine, and re-measure the voltage at the battery terminals to confirm it is within the normal range of 13.5 to 14.5 volts.