U3978

U3978 Ford engine fault code diagnosis, code meaning,symptoms and how to fix it.

U3978 Diagnosis

The axle lift 2 output circuit is commanded OFF, but air pressure is detected at the pressure feedback switch. Troubleshoot for axle lift 2 air solenoid fault, and for air pressure switch short circuit fault.The BHM is detecting more than one smart switch with the same ID number present on the vehicle. The outputs controlled by the switch and the indicator in the switch are commanded FF.

The BHM drives the 5 cab overhead clearance and ID lamps from connector B5 pin C on circuit 46. All other marker and tail lamps are driven from BHM connector B1,K on circuit 23. This circuit connects to the CHM as an input at connector J3,P.

Ford U3978 Fault Code Meaning :

Ford U3978 Symptoms :

Ford U3978 Reasons :

How To Fix Ford U3978 Trouble Code ?

Which Ford cars have the code U3978?

  • U3978 Ford Aerostar
  • U3978 Ford Bronco
  • U3978 Ford C-Max
  • U3978 Ford C-Max Energi
  • U3978 Ford C-Max Hybrid
  • U3978 Ford Contour
  • U3978 Ford Crown Victoria
  • U3978 Ford EcoSport
  • U3978 Ford Econoline
  • U3978 Ford Edge
  • U3978 Ford Escape
  • U3978 Ford Escape Hybrid
  • U3978 Ford Escort
  • U3978 Ford Everest
  • U3978 Ford Excursion
  • U3978 Ford Expedition
  • U3978 Ford Explorer
  • U3978 Ford Explorer Sport Trac
  • U3978 Ford F-150
  • U3978 Ford F-250
  • U3978 Ford F-350
  • U3978 Ford Fiesta
  • U3978 Ford Flex
  • U3978 Ford Focus
  • U3978 Ford Focus Electric
  • U3978 Ford Freestar
  • U3978 Ford Freestyle
  • U3978 Ford Fusion
  • U3978 Ford Fusion Energi
  • U3978 Ford Fusion Hybrid
  • U3978 Ford Fusion Plug-In Hybrid
  • U3978 Ford GT
  • U3978 Ford Mustang
  • U3978 Ford Mustang Mach-E
  • U3978 Ford Mystique
  • U3978 Ford Probe
  • U3978 Ford Ranger
  • U3978 Ford Taurus
  • U3978 Ford Taurus X
  • U3978 Ford Tempo
  • U3978 Ford Thunderbird
  • U3978 Ford Transit
  • U3978 Ford Transit Connect
  • U3978 Ford Windstar

A code is a fault code and it indicates that something has gone wrong with your car's engine.

It can be caused by many different problems, including a faulty battery, a bad fuel pump, or even a cracked exhaust manifold.

You will need to diagnose the problem before you can fix it. The best way to do this is with an OBD scanner tool.

A scan tool will tell you what needs fixing and how much it will cost in order to fix that particular issue.