2014 Prius smart key not functioning.

Symptoms: Doors does not unlock when you grab the door handle. The fob lock and unlock buttons do not work. On the fob you can see the LED light up when you press the buttons. The Start button does not start the car. If you use the key fob to press the start button the car starts. Standing next to the car the LED light on the key fob does not blink. Both key fobs did not work. On the dash I do see immobilizer symbol blinking. The scanner did pull a code B126A.

 

My sister took the key fob to the dealer ship, and they said the battery was good. She did this after the problem started.

 

I believe the SKS button is found on gen 2, not gen 3. Only the factory remote start for the Prius. When the key fob is held upto the start button the car will start. I don't think its the 12 volt battery.
This is a 2014 gen 3 Prius. The vehicle is not transmitting the SKS signal to the key fob. The vehicle is not receiving any signal from the key fob.

Does the gen 3 key fob red LED blink when it's next to the car? Does it blink even when next to a different gen 3 Prius? NOTE: Both key fobs must have the same FCC number. It will have a ACX or AAB in the FCC number. The vehicles must have the same number.

 

Update: My sister took her 2014 Prius to a locksmith to add a key, and he could not pickup the oscillator signal. It's at this point he refused to work on the car. The vehicle has an aftermarket Viper remote start that was installed in 2016. I would like to remove the Viper remote start. Because this is suspected possible cause.

 

Some interesting information about the smart key module behind the glove box. They seem to come in two different colors. Red for for the ACX key fobs, blue the AAB key fobs. I suspect this what is going on for gen 3 Prius. The replacement module will need to be programmed back into the car via toyota tec software. Key fobs need to be reset in order to be reused. Autel KM100 key program tool.

 

I have purchased a used SKS module off of Ebay, in case the aftermarket remote start removal does not work. I believe the SKS smart key module needs to be paired with the other modules in the car. Like body control and steering column lock. If any one with knowledge in this area please chime in.

 

Removing the Viper remote starting did not fix the problem with the remote and smart key functions. Next step to replace the SKS smart key module. It appears the Autel KM100 has more capabilities with respect the immobilizer than my Xtool D8. This maybe key to getting the replacement module working.

 

Deep dive down the rabbit hole.

Tried replacing the door control receiver module located on the passenger C piller in the trunk area. This did not work. So I unplugged the Oscillator module behind the high voltage battery. This then did generate a fault code. This was a clear sign that the certification ECU (SKS module) was operational. Remember I had no fault codes to work with. It's at this point my suspicion of the door receiver was primary suspect. I removed the cover off of the door control receiver. The module only has five pins. Only 4 of these have wires connected to it.

First verified I had a proper ground on pin 1. Then I got out the scope to look at electrical signals. Connect the scope to +5v pin 4. This is the yellow trace. Connected RSSI pin 2 the blue trace.

The +5v (Yellow) was pulsing high to the 5 volt level. RSSI (blue) would only pulse low when +5v was high. When I would push the lock button on the fob, the the pulsing on RSSI would stay low. The interesting thing is DATA pin 5 grey wire was always low. I never ever saw it change. I started tracing the wire back to the certification ECU, behind the glove box. When I pulled up the rear passenger door sill cover, I found mouse droppings. It's at this point I new I was investigating the a rodent issue. That's when I found this.
The mouse had chewed black sleeve. Chewed insulation off the purple wire. The mouse had completely severed the grey wire!! Repaired both wires. Wrap the whole wire harness with elelectrical tape. Tested the remote lock and smart key functions. These were all now working. After spending $55 on two Ebay modules I did not need, the car is finally fixed. The dealership would of charged more than $2000 to fix. If they could even fix it.