My cruise has been out for about a year now. When I'm going 20+ mph, I press the buttons to turn it on and nothing happens. No cruise, no dash light. I got it scanned at auto zone and it threw the code "C116A - ABS Pressure Transducer/Brake Switch Mismatch."

So far I've replaced the brake pedal switch and checked every fuse related to brakes and PCM, no cigar. What's weird is that I noticed it being out the day after I hardwired a few LED pods in. I used the included wiring, and used the proper fuses and relays all independent of the OEM fuse box and wired directly to the battery, so I don't think that should affect it. But I remember I noticed right away when the cruise control was out 'cause I used to use it so much. So that could just be a weird coincidence.

I'm thinking it could be the cruise control switches going bad, but that wouldn't explain the C116A code. I'm hoping the HCU isn't bad. I'm planning on taking it to a mechanic friend to get it diagnosed with a better computer, but possibly some of y'all have had this issue before. Thanks for any help you can give.

 

Have no idea what that means. Did you replace the high-mount stop light with LEDs? If so, put the original light back in.

 

No, I mean auxiliary offroad lights. They're LED pods that I mounted on the bumper. Nothing to do with the brake lights.

 

Does the high-mount stop lamp work? Is it the original light bulb style? Yeah it's important or I wouldn't revisit. The C116A DTC indicates a mismatch between what is being reported by the pressure transducer in the HCU and what the PCM is seeing from the BOO switch. You can check this voltage manually by probing the test fuse points on BJB fuse F82. A "normal" system will show battery voltage when the brake pedal is applied and zero volts when the pedal is released. If you measure a voltage in between those expected values, it would fall into the "indeterminate" range and the PCM won't be able to accurately detect the BOO switch position. Ironically, the high mount stop lamp's regular incandescent bulb's filament is what "pulls" the voltage "down" to zero when the pedal is not applied and the switch is not closed. If the PCM doesn't see a voltage that corresponds with a an opened switch, speed control is inhibited. It also tells the ABS module about the state of the BOO switch and that module does its own logical check of the BOO switch status vs the internal pressure transducer.

BTW, the system isn't supposed to engage a lower road speeds like 20 mph. Minimum is around 25 mph. FYI. The indicator in the cluster isn't supposed to come on until the speed is actually set. Just pressing the ON button doesn't turn on the indicator, the system has to engaged and active.