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clinebarger · 02-04-2017, 10:38 PM

The Cooler Circuit is routed to the Converter first to keep the TCC Off & Charge the Converter.
If this circuit does not have the correct volume, The TCC will drag and/or lock-up & kill the engine.

This is caused buy 1 of 2 things.....

1. Worn out pump, PR Valve Bore, or End Plug leak..... As the fluid heats up, Pressure & Volume drop, The Pressure Regulator Valve will put a priority over the Cooler Circuit to maintain Line Pressure, The symptoms will happen at idle because that's when the pump is least efficient.

2. EPC "amps" to low at idle, (To much pressure demand), Amps should hover right around 1.00 at idle. Have you "Learned" the TPS value on the controller?? The controller must know where closed throttle/idle is!

To low of a curb idle can also cause this.

02-04-2017, 10:38 PM	#110
clinebarger Senior Member Join Date: May 2009 Location: Fort Worth, TX Posts: 6,370	Re: 4L80E & TH400 Tech. The Cooler Circuit is routed to the Converter first to keep the TCC Off & Charge the Converter. If this circuit does not have the correct volume, The TCC will drag and/or lock-up & kill the engine. This is caused buy 1 of 2 things..... 1. Worn out pump, PR Valve Bore, or End Plug leak..... As the fluid heats up, Pressure & Volume drop, The Pressure Regulator Valve will put a priority over the Cooler Circuit to maintain Line Pressure, The symptoms will happen at idle because that's when the pump is least efficient. 2. EPC "amps" to low at idle, (To much pressure demand), Amps should hover right around 1.00 at idle. Have you "Learned" the TPS value on the controller?? The controller must know where closed throttle/idle is! To low of a curb idle can also cause this.