Replaced brake switch and still...

[Chazz77]

I am still having random immobilizer issues. I replaced the brake switch which should have fixed it. Car has newer battery with strong voltage. Randomly car will not start. All lights come on, seat adjusts and immobilizer light comes on. Car won't start. Wait three-five minutes with multiple attempts to start car fires right up. 2012 4.6. Brake switch was supposed to remedy, and logically it should have.

 

[joegr]

Logically, if it were the brake switch at fault, it would have acted like it does when you press the start button without your foot on the brake. When you do that, it goes into accessory mode. This is not what you are describing.
There are a whole bunch of things that could result in the symptoms you have. Could be a fob authentication issue, transmission gear interlock, ..., all the way to a failing starter motor (seems to come up a lot). That leads to a whole bunch of parts to throw at this problem and hope that one fixes it. Or, with the service manual and the right tools, you could diagnose the problem and replace only the failing part. If you don't have those items, then you may have to take the car to someone who does to figure it out.

 

[Chazz77]

Logically, if it were the brake switch at fault, it would have acted like it does when you press the start button without your foot on the brake. When you do that, it goes into accessory mode. This is not what you are describing.
There are a whole bunch of things that could result in the symptoms you have. Could be a fob authentication issue, transmission gear interlock, ..., all the way to a failing starter motor (seems to come up a lot). That leads to a whole bunch of parts to throw at this problem and hope that one fixes it. Or, with the service manual and the right tools, you could diagnose the problem and replace only the failing part. If you don't have those items, then you may have to take the car to someone who does to figure it out.

Thanks Joe! It does go into accessory mode, I failed to mention. At one point the "Press brake pedal to start" displayed while brake was pressed. Two different fobs with new batteries. Two very respected shops with access to service manuals have looked at this including the shop that installed the brake switch, no answers. Completed a 2400 mile trip last week with multiple starts and immobilizer engaged 3 times, so it has improved greatly with new brake switch.

 

[joegr]

In that case, then check the wiring to the switch and the connector at the switch. Maybe try some cleaner on the contact areas (Hosa D5S-6 CAIG DeoxIT, for example).
I have also found that most (all?) aftermarket parts like this are not so good. The actual Hyundai parts don't cost much more anyway, its just that they sometimes take longer to get.