A 2013 Ford S-Max rolled into a British workshop recently with an inoperative cruise control. The scanner pulled four codes: C1D2249, C200349, B10AC95, and B111515. The first three codes point directly at the steering wheel controls, but the final code points to the high-mounted stop lamp. Looking at our own data from the Wrenchlane platform, diagnosing this requires understanding how Ford manages circuit failures across different modules.
The steering column suspects
When right and left switch signals are implausible (C1D22:49 and C2003:49) alongside a cruise control switch malfunction (B10AC:95), a probable cause is a fractured clock spring ribbon. Our diagnostic engine ranked this at an 85 percent probability. The Ford EUCD platform uses a multiplexed analog resistive ladder network sharing common ground and reference lines through the clock spring. Continuous cyclic fatigue causes micro-fractures in the copper traces. Increased resistance alters voltage drops, which the Body Control Module and Steering Column Control Module detect as out of range.
The required test is pin-to-pin continuity and resistance sweep testing of the clock spring ribbon conductors under rotation. Live data PID monitoring of the switch states while turning the wheel from lock to lock will also catch intermittent opens.
If the clock spring is intact, the switch assembly itself (ranked at 70 percent probability) or the SCCM connector (45 percent) are the next logical checks. Internal silicone tactile dome contacts oxidise over time. Thermal expansion can crack the internal surface-mount resistors. You can verify this using a multimeter to measure resistance across the switch module pins while actuating each button.
The tailgate interlock
The wild card in this code list is B1115:15. This code indicates an open circuit or short to battery on the high-mounted stop lamp. Our engine ranked this as a 78 percent probable cause for the cruise control failure.
On the S-Max, the rubber corrugated conduit connecting the roof to the tailgate takes intense flexing every time the boot opens. The wiring harness inside eventually snaps or chafes. Ford software enforces a critical fail-safe interlock. If any brake light circuit registers an open circuit, the powertrain control module inhibits cruise control engagement. This prevents runaway acceleration if brake disengagement feedback fails. Code B1115:15 will physically lock out the cruise control system, regardless of whether the steering wheel switches work perfectly.
Verifying this is simple. Look at the high-mounted center brake lamp with the brake pedal depressed. If it is out, inspect the wiring inside the upper tailgate rubber conduit boot.
Putting it into practice
Checking multiple codes in isolation often leads a technician to replace a clock spring when a broken tailgate wire is the actual culprit. Look at the brake lights before tearing down the steering column. Has a hidden fail-safe ever cost you hours of diagnostic time on a seemingly straightforward job?