4t40/45 TFT sensor assy

[gectek]

here is what you were wanting to know, and this is why i wouldnt hack into the harness for anything trans related really. first part is press, second is temp. if you do want to do this though, maybe using the auto trans interceptor would be a good idea, since it plugs inline and can give you a place to tap in to, and still keep the press normal. but thats just a thought and i would recommend using the non electrical components for the values you want

The automatic Transmission Fluid Pressure (TFP) manual valve position switch assembly is attached to the control valve body. This assembly contains six fluid pressure switches and the automatic transmission fluid temperature sensor.
Five of the fluid pressure switches are normally-open. These are used to indicate the position of the manual valve. The PCM uses this information to control line pressure, TCC apply and release and shift solenoid operation.
The release pressure switch is used as a diagnostic tool to confirm that the TCC is actually OFF when it has been commanded OFF by the PCM. This switch is normally-closed.
Each fluid pressure switch produces either an open or a ground to the PCM depending on the presence of fluid pressure at the switches. The sequence of open and closed switches produces a combination of voltage readings. The PCM monitors these readings.
The PCM measures TFP manual valve position switch signal voltage from each pin to ground and compares the voltage to a TFP manual valve position switch combination table stored in the PCM memory. If the PCM does not recognize the switch sequence diagnostic code will be set as a result. A diagnostic code may also set if the TFP manual valve position switch sequence indicates a gear range selection that conflicts with other sensory inputs to the PCM.

Fluid Pressure and Circuit Combination
see pic


Valid combinations for circuits A, B, and C are shown in the table. LOW means that the switch is grounded with a resistance less than 50 ohms at 0 volts ; HI means that the switch is open with a resistance greater than 50 K ohms at 12 volts .
Note that resistance should be measured with the engine running. When the transmission's pass through connector is disconnected from the vehicle harness while the engine is running, multiple diagnostic codes will set. Clear these codes when you are finished with this procedure.


ALSO:
Automatic Transmission Fluid Temperature Sensor





The automatic Transmission Fluid Temperature (TFT) sensor is a negative temperature coefficient thermistor that provides information to the PCM regarding transmission fluid temperature. The TFT sensor (1) is integrated in the automatic Transmission Fluid Pressure (TFP) manual valve position switch assembly which is bolted to the control valve body. The sensor monitors main line pressure from the inside of the control valve body in order to determine the operating temperature of the transmission fluid. The sensor uses an O-ring seal to maintain fluid pressure in the control valve body.
The internal electrical resistance of the sensor varies in relation to the operating temperature of the transmission fluid. The PCM sends a 5-volt reference signal to the sensor. This measures the voltage drop in the electrical circuit. A lower fluid temperature creates a higher resistance in the TFT sensor, thereby measuring a higher voltage signal.
The PCM measures this voltage as another input to help control line pressure, shift schedules and TCC apply. When the TFT reaches 140°C (284°F) , the PCM enters hot mode. Above this temperature the PCM modifies the transmission shift schedules and TCC apply in an attempt to reduce fluid temperature by reducing the amount of heat generated by the transmission. During hot mode the PCM applies TCC at all times in Third and Fourth gears. Also, the PCM performs the 2-3 and the 3-4 shifts earlier in order to help reduce the generation of fluid heat.

[gectek]

here is what you might look for with a multifunction gauge with alarms...

http://www.dakotadigital.com/index.cfm/page/ptype=product/product_id=472/category_id=252/home_id=59/mode=prod/prd472.htm

[prophiseer]

actualy running a tanny interceptor now, but I'd need the line pressure chart to more accurately adjust the tranny by tapping the line.

the only reason I considered pigtailing a temp gauge to the factory harness would be for a more accurate internal reading . . . but I'm also toying with the idea of a junction block at the line tap, one for a tranny gauge and one for the fluid temp.

the electronic way is a bit cheaper and less labor intensive, but things would have to be wired dead perfect to not screw with the PCM's inputs, which can be a pain considering how sensitive the control modules seem to be at times.

[gectek]

well i think just a press sender in the line tap and an inline block sensor for the temp in the press line and that gauge with the alarm, and that wouldnt be hard at all. and as for the auto trans interceptor, i would take that out. it makes bad things happen to the spacer plate. i used mine for a few months and when i overhauled mine, i looked at the spacer plate and it had bad marks where the checkballs were. the prob is it uses a linear pressure adjustment, meaning it gives the same press increase reguardless of any RPM or other factor, and that is very bad on the trans. if you want more line press, use the DHP PT or HP tuners software. those are the only really safe way to do that. if the wear gets bad enough the check ball will lodge in the spacer plate and that isnt good at all.

[gectek]

here and here...lol

but the trans doesnt just use those parameters to decide pressure, depends on if it is in hot mode, what the temp of the fluid is, if the TCC is engaged, alot of variables. thats why the hard wired parts are alot better, less evasive and just as accurate. with minimal wiring

[prophiseer]

yeah, I hear that. Right now I've got it just barely adjusted off the bottom; just enough to firm things up, but not have it slap into gear. I was a little disappointed by the tranny adjustment with the DHP PCM, but until I order their tuner setup . . . I'm actually trying to convince our shop management to throw down for the licsensed package, but they're heasitant to throw down almost $3k.


EDIT: hey, thanks on that; but I already have those charts. I thought you might have the line values for the tranny in (D). I'll have to look up the base D value on Mon when back at the shop, but I'm fairly certain I don't have any of the "in-gear" specs for it, aside from the PCM's control listings, etc.

[gectek]

well when they offer the V8 codes it will be well worth it then, then the price will prob go up from there

[prophiseer]

I'm sure, and we deal with a lot of GM 8's at our shop; but I swear shop management must be trained by Ford bean-counters sometimes

[gectek]

yah, i mean if i were a shop manager, the only numbers i would like to see are HP/TQ and $$ in. You have to spend money to make money.

[prophiseer]

yeah . . . but doing performance work and custom installs on stuff, you can jack the labor rates a bit more, especially if it involves a lot of fab time; our shop has the money, no doubt . . . but you'd never be able to tell walking in the place . . . friggin' Sanford & Son, man

[gectek]

well on my rebuilds youll notice there is no labor charge in there. i prob should add it, and i might have to if it starts to get to where im not making enough to justify the process, but im keeping it inexpensive and simple to keep it that way for me also.