Hello everyone!

I replaced a bad ECU with a used one I bought from eBay.
Techstream accepted VIN, Seed number and Pass-code, leading to the next step which was supposed to take 16 mins.
But the following message popped up. Battery voltage low?? I don't get it. The car battery is 13.6 volts. (even my key battery is 2.98 volts.)
Multiple attempts but the same error message again.
Mini VCI cable and Techstream have no issues as far as I can tell. I connected them to my other Lexus and Sienna and everything looked normal.

Did anyone have this problem? Perhaps the used one (ECU) is bad as well?

Will

 

Did you ever figure this out?

I'm getting this same error now, after reseeding, trying to register the first key.

It says I have 120 seconds to remove the key and replug the key and turn the ignition on.

At this point, I have to have a used/working smart key in the slot to even turn the ignition on

So I turn off the car, pull out the key and reenter it, and turn it back on, wait 5-10 seconds and click retry on Techstream and it gives me that same error as you.

I've done this part before many times too, an never gotten this error, not sure why.

UPDATE: Okay, guess I figured it out. Once the immobilizer is reseeded, it goes into auto registration mode, there is no need to use the key registration utility to register the two keys... its done automatically, I totally missed that part about this immobilizer. Just plug a key in, turn on ignition leave in for 30 seconds turn off, plug in another key, turn ignition on wait 30 seconds, turn off, then press power button 5 times within 10 seconds to exit auto registration mode. Then move on to Smart Code Reset an reprogram the smart side of the key if its a smart key.

The battery voltage 8v error was triggered by the car being in auto registration mode after the immobilizer reset. Once its out of auto registration mode, it will walk you through the steps to register a 'new' key with the utility and work just fine.