Originally Posted by Prismatic

We're all just going to casually ignore that he's got a code for a malfunctioning TCC? If he doesn't have lockup he'll overheat in no time towing.

Originally Posted by Prismatic

Sounds like you've lost lockup. It could be the solenoid pack or the TCC its self.

Originally Posted by FabricGATOR

Like I said previously, there is some sort of thermal (mechanical) transmission thermostat that stops the oil cooler from circulating until the transmission gets up to operating temperature.

I googled
545RFE transmission thermostat
and sure enough, sometimes it fails and get stuck in recirculation mode.

Symptoms:

• Overheating
• Overheated fluid

Cause:

The thermal bypass valve in the OE cooler bypass valve can become stuck in the cooler bypass position, causing hot fluid to circulate in the transmission that leads to overheating.

** It looks like this valve block may (luckily) be external to the transmission AND I would get a replacement thermal valve and NOT THE SONNAX BS CHEAT PART unless you never expect tooperate in cold climate...

Please let us know what you find and how you fix it.

PS, in MY a604 transmission from my minivan, I would have to remove the transmission and open the cavity to change this part.... so you area lucky if this is external..