F-150 Multiple Systems Inoperative – One Cause!
May. 01 2023
May. 01 2023

Vehicle: 2016 Ford F-150, 4WD, V8-5.0L, Automatic transmission/transaxle

Mileage: 122,872

Problem: The customer had her F-150 towed into the shop because the radio, HVAC controls and the electric power steering were inoperative.

Case Details: The technician connected a scan tool and found the following diagnostic trouble codes (DTCs).

  • P0563 - System Voltage High
  • P0625 - Generator Field Terminal Circuit Low
  • P065B - Generator Control Circuit Range/Performance

There seemed to be no correlation between the customer’s concerns and the DTCs, so the technician called ALLDATA Tech-Assist. The consultant advised that low voltage could negatively impact all the systems on the list. He recommended checking the charging system first, starting by verifying there was battery voltage on the brown/red (BRN/RED) wire at the alternator.

The technician tested the charging system and found it was not working properly. A close inspection of the wiring near the alternator revealed that the BRN/RED wire was corroded about six inches from the alternator.

Confirmed Repair: He repaired the wiring, cleared the DTCs, verified the charging system was working correctly and road-tested the vehicle. All systems worked properly. Problems solved!

The ALLDATA Tech-Assist team fields cases like this every day. See how Tech-Assist can help your shop save time and money with on-call diagnostic support from ASE-certified Master Technicians. More Tech Tips 

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