Network, generic

U0138 Lost Communication With All Terrain Control Module

Check engine lightUsually off

EmissionsNot relevant

Drive cycleNot required

Limp modeNo

U0138 is logged when another module no longer receives the all-terrain control module, the unit behind the selector that lets the driver pick a terrain or drive mode such as snow, sand or mud and then adapts traction control, throttle response and shift points. Ford lists U0138 in the OBD code tables of its 2014 vehicles and marks it as available in all three self-test modes, without an entry in the lamp column. More public manufacturer detail is missing. CARB treats such a link as a digital input whose loss of communication must carry its own code. Implausible data from this module is U0439; the transfer case and AWD clutch use U0102 and U0114. The mode selector stops working and a 4WD or traction warning appears.

Likely causes

Fuse, supply, ground or CAN wiring of the terrain module faulty

Loose or corroded connector at the module or the mode selector

All-terrain control module internally faulty

Symptoms

Terrain or drive mode cannot be selected
4WD or traction control warning lamp

Repair estimate

DifficultyMediumWorkshop job

Parts and labour€60–1,200

Time0.5–3 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

all terrain modulecan bus wiring

Related codes

U0439 U0102 U0114

References: performanceparts.ford.com, law.cornell.edu.