P261C immediatly after ABS (booster and acctuator replacement) Pump running & not overheating

2010 Prius - P261C immediately after brake actuator/booster replacement. Pump appears to be running. Looking for ideas.

I just replaced the ABS actuator and brake booster assembly on my 2010 Prius (~260k miles). Using Techstream I completed Linear Valve Offset Learning and all ABS/VSC/TRAC codes are now gone.

However, I'm now getting P261C (Engine Coolant Pump Motor "B" Control Circuit Low).

Facts:

• P261C was not present before the brake actuator job.

• I can clear the code with my Veepeak scanner, but it returns in less than a minute.

• The engine coolant pump is an AISIN pump with about 120k miles on it.

• I physically put my hand on the pump and can feel a steady vibration, so it appears to be running.

• Coolant temperatures are generally around 180°F, and I saw a peak of about 208°F driving home in 104°F Phoenix weather.

• The car is not showing signs of immediate overheating.

• The water pump connector looks clean and plugged in properly.

• During the actuator replacement I moved the inverter reservoir, intake manifold, and worked around the large engine wiring harness that runs across the top of the engine.

• I did have to fight some of the harness retainers/protectors while removing the intake manifold, and I was pulling up on the harness in front of the booster at times to access bolts.

Questions:

1. Has anyone seen P261C caused by wiring/harness damage even though the pump is still running?

1. Are there known trouble spots in the Gen 3 harness between the ECM and engine coolant pump?

1. Is there a Techstream Data List item or Active Test that can help determine whether this is a pump issue versus a wiring issue?

1. If you've had P261C with a visibly/physically running pump, what ended up being the root cause?

Any insight from those who've chased this code would be appreciated.

 

PS - I deleted the code and as soon as the car started it came back...