[atoman]

This info is specific to 41TE with ATF+4 fluid, but general guidelines apply to others as well.

FLUID LEVEL CHECK
The transmission sump has a fluid level indicator
(dipstick) to check oil similar to most automatic
transmissions. It is located on the left side of the
engine. Be sure to wipe all dirt from dipstick handle
before removing.

The torque converter fills in both the P Park and N
Neutral positions. Place the selector lever in P Park
to be sure that the fluid level check is accurate. The
engine should be running at idle speed for at
least one minute, with the vehicle on level
ground. At normal operating temperature 82° C
(180° F), the fluid level is correct if it is in the HOT
region on the oil level indicator (Fig. 209). The fluid
level should be within the COLD region of the dip-
stick at 27° C (80° F) fluid temperature.

If you have access to the temp sensor data, with DRBIII or equivalent scan tool OR you can measure the fluid temperature, refer to the following chart for correct fluid level:

 

[Jeepman]

That's great info Atoman, thanks.

The way I see it:
Cold: Vehicle is cold, start the engine, and run for a minute or two. Check the level using the cold range on the dipstick.

Hot: Drive the vehicle for 15 minutes, then check using the hot range on the dipstick. The Owner Manual says something like this as well. My sense is that many do not get their transmission fluid hot enough to take a proper "hot" reading, hence the over filling which is common. The transmission fluid warms up slower than the engine coolant by 5 to 10 minutes, in fact on a cold day, the engine coolant helps heat up the transmission fluid via the cooler in the radiator.

Engine cold, not running: The transmission fluid will be close to or at the notch in the dipstick. That makes for a quick check as to major loss of fluid. Keep in mind that the transmission holds a lot of fluid, a little under is better than a lot over.

The transmission dipstick has meaningful information on it: http://forum.chryslerminivan.net/sh...r-transmission-s-dipstick?p=194780#post194780

How the transmission responds as the fluid warms up from a cold start. It does not shift normally until warmed up to 80F: http://forum.chryslerminivan.net/sh...engage-in-drive-when-cold?p=153223#post153223

There is an "extreme cold" schedule when the oil temperature is below -16 degrees F that allows Park, Neutral, Reverse, 1st and 3rd gears only. If the oil temperature is between -12 degrees and 10 degrees F, it uses the "super cold" shift schedule that delays 2-3 and 3-4 upshifts, and provides an earlier 4-3 and 3-2 coastdown shifts. High speed 4-2, 3-2 and 2-1 kickdown shifts are prevented in this mode. When the ATF is between 10 and 36 degrees, the "cold" schedule takes over and the transmission shifts at higher throttle openings and high speed 4-2, 3-2 and 2-1 kickdown shifts are still prevented. Also, there is no torque converter clutch lockup in the cold, super cold or extreme cold ranges.
Once the ATF is above 40 degrees, the TCM goes to the "warm" schedule which allows normal upshifts, kickdowns and coastdowns, but still no torque converter lockup. When the ATF reaches 80 degrees, the TCM changes to the "hot/normal" mode and begins to engage the torque converter when vehicle speed is above about 22 mph.

A temperature gage for the transmission fluid would be neat. I believe I have seen aftermarket gages mentioned on here.

 

[ronman]

One thing that makes it tricky is that since the tube is so curved, the dipstick can pick up fluid from the sides on the way down. This ends up looking like the fluid is at the proper level on one side of the dipstick, but not on the other, just 1/8 inch away, even after several wipes and re-insertions! It can cover 9/10 of the entire width, but have just enough dry on the edge of the dipstick to make you wonder if you're getting a true reading. Any experience with that?

 

[Jeepman]

One thing that makes it tricky is that since the tube is so curved, the dipstick can pick up fluid from the sides on the way down. This ends up looking like the fluid is at the proper level on one side of the dipstick, but not on the other, just 1/8 inch away, even after several wipes and re-insertions! It can cover 9/10 of the entire width, but have just enough dry on the edge of the dipstick to make you wonder if you're getting a true reading. Any experience with that?

Try checking when cold. If it is in the cold range then you are okay. See Post #2 above. Getting a consistent reading when hot takes some patience.

 

[atoman]

One thing that makes it tricky is that since the tube is so curved, the dipstick can pick up fluid from the sides on the way down. This ends up looking like the fluid is at the proper level on one side of the dipstick, but not on the other, just 1/8 inch away, even after several wipes and re-insertions! It can cover 9/10 of the entire width, but have just enough dry on the edge of the dipstick to make you wonder if you're getting a true reading. Any experience with that?

Look closely at the holes in the dipstick, they're there for a reason - no errant tube runoff will cover a 'range' separation hole.. also, the reading is taken where the atf film crosses the middle of the dipstick, not one edge or another. It also helps to allow some time to pass before checking fluid, especially if you're adding more ATF to the trans (it takes a little while for it to run down the sides of the tube)

 

[threeoten]

I just checked mine after doing a 41TE fluid replacement, it's 20° outside and so I ran the van for probably 15 minutes in park to get the transmission temp up to 80° (measured with an infrared thermometer) as indicated as "cold" by the chart above, and the dipstick read just above the first 'hot' fill hole - which makes me think it's too full. Does my procedure seem correct? Is using an IR thermometer on the bottom of the pan a good way to get a temp reference in order to use the graph above?

 

[Sienile]

Using an IR thermometer externally will not give you accurate fluid temps. It might get you close, but I wouldn't count on it.

 

[atoman]

I just checked mine after doing a 41TE fluid replacement, it's 20° outside and so I ran the van for probably 15 minutes in park to get the transmission temp up to 80° (measured with an infrared thermometer) as indicated as "cold" by the chart above, and the dipstick read just above the first 'hot' fill hole - which makes me think it's too full. Does my procedure seem correct? Is using an IR thermometer on the bottom of the pan a good way to get a temp reference in order to use the graph above?

The chart above references temp as measured by the temp sensor integral to TRS (Trans Range Sensor), which is above the valve body that's 'under' (above) the pan...

It is better to check the level once the engine is fully warmed up (@N.O.T.) and van has been driven (not parked) an additional 15+ minutes - this will give you the hot range (even if it's not at an exact temp).
It is critical that the hot level be in correct range as most 'work' will be done when trans is 'hot' and too high an ATF level can cause cavitation and aeration of the fluid (bubbles of air in hydraulic fluid - this can cause mechanical failure via inappropriate timing of controls)

 

[threeoten]

Does anyone know of an OBD app (ideally for iOS) that can read the trans temp?

 

[Sienile]

Not sure if it works for iOS, but Torque works with ELM327 bluetooth OBD2 adapters.

 

[threeoten]

Not sure if it works for iOS, but Torque works with ELM327 bluetooth OBD2 adapters.

Thanks, do you happen to know how I'd set up the app to read transmission temp on my 02 Caravan?

 

[Sienile]

The adapter plugs into your OBD2 port and you pair it to your smartphone. It should come with instructions for pairing... Been so long since I set mine up that I can't remember if it's done through the main bluetooth settings or the app itself, but I think it's the phone settings.

In the app you press the screen to get a menu to add gauges and displays. Trans temp should be on that list.

Not 100% sure if it reads an '02, never tried it on one of that generation. The ELMs read most, but not all PCMs.