B5 - Under Voltage Test

^ Disconnect regulator.

^ Check resistance between regulator A and F terminals.

^ Resistance should be more than 2.4 ohms.

2.4 ohms or less -- Replace regulator. Check alternator for shorted field circuit and service if required. Go to B2. B2 - Base Voltage and No Load Test

More than 2.4 ohms -- Go to B6. B6 - A Terminal Voltage Check