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TCM was my typo. I should have typed TDM for time delay module. The little black box by the caddy valve. You are correct the transmission control has nothing to do with it.
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OKMake sure all the air is out of the coolant lines. Since truck sat higher then the back. Sounds like there might be an air pocket near the thermostat. Next if been realy cold and the truck been sitting. Take a hair drier and run it blowing on the Cadillac valve. There is a possibility that it's stuck.. Next check the connections from the themostaic switch and or the switch is bad. One other thing. It wouldn't be unusual for the truck to have the wrong thermostat installed. This seams to be a common issue with former NG trucks. Also check the power steering fluid level. Fan clutch is activated by theCadillac valve when the Thermostatic switch sense the Temp is to hot and activates the the fan.. Also you need to really just drive the truck.
Sent from my SM-J727U using Tapatalk
Sent from my SM-J727U using TapatalkThe fan should kick in somewhere between 230 and 240 but military gauges are build by the lowest bidder so you never know exactly how accurate they're going to be. If the fan kicks in at the same point every time the engine heats up you're probably good to go.
Thanks for the detailed write up milcommoguy."Fan kicking on" (clutch locked-fan working) is really a good Cadillac valve solenoid, de-energized (no 24 volts applied) The logic here is backwards for many thinking something on is energized to work. That's is why un-pluging Time Delay Module TDM locks up fan (must have good working clutch and valve)
Engine running, Cadillac valve solenoid always has 24 volts applied do to temperature switch in water crossover that is normal closed (feeds TDM) until it reaches about 230 F then switch opens, removing power to Cadillac valve and removing PS pressure to clutch... then the fan kicks on. This switch is normally closed below 190 F +/- hysteresis.
That said failure of Cadillac valve solenoid (common, shorted coil winding's (should be 58 to 78 Ohms), then excessive current, then fail / blown TDM,) then fan always engaged are common issuse. Clogged-up & stuck valve could do it too.
Fan disengage also can occur when the "Kick Down Switch" at right side of injector pump (Peddle to the metal) is triggered to start a timed fan disengage... to enter a stream or get a boost of power from HP hogging fan.
Simple test measure resistance of coil 58-78 Ohms. If less, it is shorted! DO NOT connect TDM. If more, likely open. Any low resistance (<10k Ohms) from either lead to ground, toss it. Time for a new valve, test and then maybe new TDM. Also note coil and valve run warm to more than warm at coil.
Failure of any of these fan system controls / components assures that fan is engaged.
CAM
What about the question I just asked?I just wanted to mention here that most failures with the Kysor-Cadillac valve are from failed coils and usually not the valve internals and that coil can be easily replaced for considerably less money than a new solenoid valve. Google "24V solenoid coil" and you'll find plenty of them under $50. If the valve itself fails it's usually due to crud in the system (like teflon tape) that can be cleaned out by disassembling the valve body.
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