I know the OD is not allowed to come on until the engine gets to a certain temperature, not sure if the LU was that way or not.

 

The transmission sensor/solenoid information that you ask about is listed in the factory service manual (FSM) - the FSM can be downloaded for free in the stickies at the top of this forum (specifically here).

How do you know its the torque converter, and not OD?

If you are positive the converter lockup is the issue (not OD), and you haven't already checked your bellcrank bushings, check them for play. Worn-out bellcrank bushings will damage the TPS and cause undesirable behavior. GAmes has a good writeup on replacing them, which you can find through the search feature (do an advanced search for posts on bellcrank bushings by user GAmes). There is also at least one trouble/diagnostic code that will cause TCC-lockup cycling without setting the MIL/CEL - you need a scan tool to find it. Since your truck is a '96, like mine, the OBD-II scan tools at the chain parts stores can check for trouble codes.

 

From the FSM: Transmission fluid temperature readings are supplied to the transmission control module by the ther mistor (Fig. 6). The temperature readings are used to control engagement of the fourth gear overdrive clutch, the converter clutch, and governor pressure. Normal resistance value for the thermistor at room temperature is approximately 1000 ohms. The PCM prevents engagement of the converter clutch and overdrive clutch, when fluid temperature is below approximately 10°C (50°F)

So I'm not that great at electrical troubleshooting but am I correct that I could remove the solenoid and have it in the house at room temp (low 70s) and check resistance to see if it's 1000 ohms?

 

Sorry I failed to mention that I bypassed the TPS and used a 5k Pot

 

It's in a seemingly odd section (the Fuel section), but on page 14-126 of my '96 FSM there is a temperature/resistance chart for the transmission temperature sender (I've attempted to include a screen snip). If you want to drop the pan and pull the sensor, you could try testing it in air, or putting it in water or ATF of a known temperature. Alternatively, if you take the pan temperature (IR thermometer) and assume the fluid is close to that temperature, you could test resistance at the transmission harness connector (that may be difficult to reach). If you have a temperature sensor for your multimeter, maybe you could tape it to the transmission dipstick so the end actually gets immersed (again, test at the harness connector). With options #2 & #3, you'll also have a little wiring resistance but it should be negligible. If resistance is way off in that case, then you probably would want to test the sensor separately to see where the issue is.

 

Thanks a lot! Will check, today or tomorrow

 

Good luck - let us know which approach you used. BTW, I assume you don't have a scan tool - transmission fluid temperature can be checked with a scan tool (though some scan tools do not read that piece of data accurately from the PCM).

 

Correct, I don't own one. Do you have a recommendation?

 

Not a firm recommendation. I know of a user on another forum who used a Foxwell NT520 - I'm sure other Foxwell tools can do it (NT640 or NT624 Pro if still available) but you need to check their website to see what they have these days. I suspect the Innova 5160RS or 5610 will also work, as they claim to read transmission temperature - but I have no experience with either. I have a Snap-On Modis (has both scan and scope) that I bought used - oddly, it does not accurately read transmission fluid temperature on my Dodge in spite of being a pro-level tool back in it's day (the owner of my favorite transmission shop once told me that Snap-On had some issues with that years ago).