Started happening intermittently a couple weeks ago. Normally, you get in with keyfob in pocket, depress brake pedal, little key icon in instrument cluster lights up green, press start button, engine starts away you go. That part was not working at all, with any of the three keyfobs. Change batteries in keyfob - same. Try the dead-battery-in-keyfob process; press the start button with the end of the keyfob. That works for a couple days, get it to the dealer. Dealer looks at it, all seems normal, press brake, green key-light comes on, start, go. Once in a while, the traction control and TPMS warnings come on.
Intermittent problem. Comes and goes. Finally comes and does not go away, CX5 trailered to dealer. Full diagnostics. Find an intermittent fault in the brake pedal switch. In this CX5, there are two brake pedal switches, one turns on the brake lights, the other switch closes to tell the computer that the brake pedal is depressed. It was the second one that was faulty. The tech found it by hooking laptop to CX5, and looking at real-time data for the various inputs. Saw that the CX5 detected presence of keyfob, and that keyfob fingerprint verified against fingerprints stored in ECU. Saw that ECU did not see the brake pedal depressed. Kicked brake pedal with boot, then the ECU saw the brake pedal depressed, and CX5 would start. Kicked pedal again, and switch went back to inoperative. Faulty switch. Replaced, everything works as normal. $450 for diagnosis and replacement of brake pedal switch.
It makes sense that the dead-battery-in-fob process would not work either. If your fob battery is dead, you get in car (do not press brake pedal yet) and press start-button with the end of the keyfob with the logo, with the logo facing the driver. One press and release and nothing should happen. Press again, and the instrument cluster and warning lights should all light. NOW press the brake pedal, and press start button again with keyfob and car will start. If you press start button again with keyfob and brake not pressed - or like ours with the brake pedal switch not working - the CX5 just shuts off and does not start.
The odd part is that all the time this was crapping out we were thinking keyfobs. Did everything we could to the keyfobs, replacing batteries multiple times, tapping the fobs against the dash, fastening the fob an inch away from the start button. It seemed obvious that the fobs were bad. At the same time, the buttons on the fobs would open and lock doors, and activte panic. 20-20 hindsight says if the fobs can lock/unlock doors, they are fine, look further somewhere else.
Anyways, I hope my experience can save someone else a bunch of keyfob cussing. This vehicle is 10 years old and 130k miles, far from worn out, but as my and other CX5s get on in years, these pesky little failures are going to start catching us.
Cheers.
Intermittent problem. Comes and goes. Finally comes and does not go away, CX5 trailered to dealer. Full diagnostics. Find an intermittent fault in the brake pedal switch. In this CX5, there are two brake pedal switches, one turns on the brake lights, the other switch closes to tell the computer that the brake pedal is depressed. It was the second one that was faulty. The tech found it by hooking laptop to CX5, and looking at real-time data for the various inputs. Saw that the CX5 detected presence of keyfob, and that keyfob fingerprint verified against fingerprints stored in ECU. Saw that ECU did not see the brake pedal depressed. Kicked brake pedal with boot, then the ECU saw the brake pedal depressed, and CX5 would start. Kicked pedal again, and switch went back to inoperative. Faulty switch. Replaced, everything works as normal. $450 for diagnosis and replacement of brake pedal switch.
It makes sense that the dead-battery-in-fob process would not work either. If your fob battery is dead, you get in car (do not press brake pedal yet) and press start-button with the end of the keyfob with the logo, with the logo facing the driver. One press and release and nothing should happen. Press again, and the instrument cluster and warning lights should all light. NOW press the brake pedal, and press start button again with keyfob and car will start. If you press start button again with keyfob and brake not pressed - or like ours with the brake pedal switch not working - the CX5 just shuts off and does not start.
The odd part is that all the time this was crapping out we were thinking keyfobs. Did everything we could to the keyfobs, replacing batteries multiple times, tapping the fobs against the dash, fastening the fob an inch away from the start button. It seemed obvious that the fobs were bad. At the same time, the buttons on the fobs would open and lock doors, and activte panic. 20-20 hindsight says if the fobs can lock/unlock doors, they are fine, look further somewhere else.
Anyways, I hope my experience can save someone else a bunch of keyfob cussing. This vehicle is 10 years old and 130k miles, far from worn out, but as my and other CX5s get on in years, these pesky little failures are going to start catching us.
Cheers.
