Flashing gears and fuel gauge. Car Not Going Into Ready. Code B1260

Hello guys long time lurker, first time poster.

I purchased a 2008 Prius that has the gear numbers and fuel gauge blinking. The vehicle has 240k miles with a recently replaced hybrid and 12 volt batteries.

When you press the power up button, all the lights on the dash come on. At that point a normal car would go into ready mode, but in this case after 8 to 10 seconds, the gears and fuel gauge start flashing.

Upon hooking up TechStream (although it does not read/display the VIN) and doing a health check. Under gateway, I have code B1260 (Transmission Control ECU Communication Stop).

I have extensively gone through most of the information on these forums.

Here is what I have done so far:

-Made sure the 12 volt battery is good and fully charged with over 12.5 volts (It is).

-Checked AM1 fuse (is good)

-Replaced the TCM with a known good TCM. Before replacing the TCM, I unhooked the 12 volt battery and made sure the car had powered down, and the previous codes had cleared up. Replacing the TCM made no difference and the problem persisted.

All in all, I am kinda stuck and not sure where to look from here.

Couple of important notes.

-IMP: Since replacing the TCM did not help, I powered down the car and unplugged the TCM wiring harness to see what that would do. When I powered the car up without the TCM wiring harness plugged in, to my surprise, that made no difference.

- It makes no difference if the TCM wiring harness is plugged in the TCM or not. The symptoms remain the same. That was quite strange. Maybe some experienced members can shed some light on that.

- For reasons unknown to me, the previous owner replaced the power on/off button of the car.

- Also, In the car was sitting a spare (ordered from eBay) key fob slot/slide in assembly and just to check if it was good or not, I swapped that spare from eBay with the one already in the car and that did not change anything. I am not sure if they one currently in the car is the original key fob hole, or the one outside. Either one seems to work.

- I was told by the previous owner that they had a key made for the car. So I'm thinking that since the key was made and apparently the car drove after that, and is powering up the car now (Although not in ready mode) the key is good?

Could this be a key fob problem? Could this be a rodent issue?
I am not sure what to do next.

I would appreciate any input from the members in the forum.

 

Thank you @mr_guy_mann I will check that and report back.

So what are your thoughts about the TCM the transmission control module unplugged and the car behaving like nothing changed? The symptoms remained the same whether the TCM is plugged in or not.

The TCM plugged or unplugged not making a difference leads me to think that there may be a break in the connection between the TCM and whatever else is on the other side where the TCM connects to.

Could something else, another module be involved here?

Where can I get the schematics that you are alluding to?

Can anyone help here who has access to this information?

 

OP here. One thing I was told by the previous owner is that (for whatever reason) they had the ignition switch (the power on/off button) replaced.
I'm not sure if that's relevant but thought I'd throw this out there.

Anyway, one thing's for certain, whatever's making the car non-responsive and not allowing it to go in ready mode is part of the very early process of a car going into ready mode. Whatever that routine is, is not being completed because it didn't matter when I plugged off the transmission control module or the hybrid battery, the behavior and/or the error remains the same.

I'm in the same boat as you, but could be a wiring or connection 'loop' not being completed issue.

Would love if someone can help with this.