Got an HDC fault special programs off flashed on the info screen. Literally 2 seconds. Then no issues - special programs all selectable. It did this twice.

No faults as per GAP tool.

recently put new (to me) lr4 rear lights in. Didn’t think this was a issue though (with brake lights) …

any other causes of a “momentary” loss of hdc?

 

Check your battery.

What did you do with your LR3 light assemblies? To each their own but I prefer the LR3 look. I have a buddy who needs one. Driver side IIRC.

 

I've had this intermittent and have researched extensively. Basically what I've learned is that it could be anything. People have pointed to the battery and brake light switch. I've replaced both. The brake light switch actually fixed the issue. That is, until I had my front two tires replaced and when I picked it up it came back w/ the lights on. Also, it was originally triggered when getting an oil change. So, I feel like it had something to do w/ a suspension sensor. But anyway, not much help but there's not going to be one answer for you. And yes, people have posted about using non OEM brake light bulbs in the truck for causing it. I have a hard time believing that but I guess anything is possible.

 

I second the battery if its on startup briefly with no codes. I had this happened before a couple times, a couple batteries with one being a dying alternator (and battery as a casualty of that). Check battery only after sitting a while so the voltage settles and check running voltage.

 

Did you fit resistors to the D4 lights ? You'll need them on the indicator circuits.

 

That's on the to-do list.

 

I retightened the negative on the battery terminal. Hopefully that cures it....