U0405

U0405 means the module storing the code received Invalid Data from the Cruise Control Module — communication is happening (so it's not a U0073 bus-off or a U0121 lost-comm), but the cruise module is sending values that fail range or rationality checks (set-speed of 300 mph, vehicle speed that disagrees with the VSS, or a checksum failure on the CAN frame). On modern drive-by-wire vehicles the 'cruise control module' isn't a separate box anymore — it's a software function inside the PCM or BCM that talks to the electronic throttle body, the steering-wheel switch cluster, and the brake-pedal switch — so U0405 is usually an input-side problem feeding bad data into the cruise function. Diagnostic order, cheapest first: (1) Scan live data while toggling the cruise-control stalk and the steering-wheel switches — if the multi-function switch reports 'cruise on' when it should be off, or vice versa, the switch resistor ladder is failing (a single resistive switch typically reads 0-5V at distinct voltage steps per button, so a corroded contact gives a bogus voltage). (2) Check the brake-pedal position switch — cruise drops out as soon as the brake switch sees the pedal move, so a misadjusted or shorted brake switch tells the cruise module 'brake pressed' permanently, which the module flags as invalid data when speed is steady at highway pace. (3) Verify VSS / wheel-speed input agreement between the ABS module's reported speed and the cruise module's expected speed — disagreement of more than a few mph triggers rationality faults. (4) Inspect the steering-wheel clock-spring connector for chafed wires inside the column. Don't replace a cruise switch before bench-testing the switch resistance with a DMM against the FSM voltage chart — guessing at a $180 multi-function switch wastes money on a $20 brake-pedal switch problem.

Vehicle-specific patterns: any GM Vortec V8 from 2007 onward (5.3L, 6.0L, 6.2L in Silverado, Tahoe, Suburban, Yukon, Escalade) and any Ford EcoBoost from 2011 onward (1.5L, 2.0L, 2.3L, 2.7L, 3.5L) use full drive-by-wire throttle, so U0405 on these platforms almost always traces back to the steering-wheel switch cluster or clock-spring rather than a discrete cruise module. 2005-2010 Chevy Cobalt and HHR throw U0405 alongside the broader ignition-recall family — clock-spring contact corrosion is the common root. 2003-2008 Toyota 4Runner / Tacoma / Tundra with electronic throttle commonly throws U0405 from a failed brake-pedal-position switch under the brake pedal bracket; Toyota issued multiple TSBs on switch design. 2007-2014 Dodge / Chrysler / Jeep with the TIPM gateway will throw U0405 alongside U0073 when the TIPM internal CAN transceiver fails — fixing the TIPM clears both codes. Estimated repair: $20 (brake-pedal switch DIY) to $700 (clock-spring replacement with SRS recalibration).