Where is the dipstick?

Oct. 12, 2015
Knowing the return of the dipstick is only a pipe dream, it becomes necessary to learn how to fill a transmission to its proper level. There are similar procedures among the manufacturers so when you get the gist of it, you can just about figure out what needs to be done.

For years now we have seen manufacturers produce transmissions without a conventional fill pipe and check level stick, which we know as the dipstick. Still to this day it becomes a conversation on the technical help line and seminars with mixed opinions regarding the subject. Some find it to be a nuisance, while others like it as not every car owner will be inclined to change the transmission fluid on their own. The question asked more often than not is why manufacturers have gone this route. I have heard many theories about it. One was that the transmissions were shipped to the assembly line prefilled. This improved assembly line procedure both in time and fluid fill accuracy. Another was a cost-saving factor of not having to produce these parts. Another was related to “Lifetime Transmission Fluids” eliminating the need for it. Yet another was to prevent pollution from spills. And finally, another was that owners neglect checking fluids so they do not need them. Perhaps there are other possibilities that I have not listed, which you may have heard. But for whatever the reason, the reality is that with each passing year there are an increased number of transmissions without dipsticks. Some manufacturers are providing a fluid level sensor to present a digital display of the fluid level. This has yet to catch on with most manufacturers and certainly does not bring back the dipstick. But at least one would know in time if a small leak had developed.

Knowing the return of the dipstick is only a pipe dream, it becomes necessary to learn how to fill a transmission to its proper level. There are similar procedures among the manufacturers so when you get the gist of it, you can just about figure out what needs to be done. This does not eliminate the need to track down specific fill procedures, as there are nuances (or nuisances) to be aware of. Some of these nuances relate to a complete dry fill of the transmission to a simple fluid and filter change. 

Generally speaking, you begin with an initial fill. Once the transmission is close to being full, most systems will require specific fluid temperatures to be reached to fine tune the level. Sometimes this may also require engagements into gear before the level is checked. The locations for draining, fluid fill and level check is where the variety of differences primarily arises, ultimately influencing the procedures involved.

Using a Nissan CVT7 transmission as an example, located on the bottom pan is a 19mm drain plug. But when it is removed, located inside the threaded area, an internal tube with a hex head bolt will be seen (Figure 1). This is the check-level or “overflow” pipe (Figure 2). This check-level pipe can be removed (Figure 3), allowing the location to double as a drain plug.

The manufacturer’s procedure begins with the disclaimer to use Genuine Nissan CVT Fluid NS-3. The specification for a complete fill is 6.9L (7 ¼ quarts). The procedure to fill and check the transmission is quite extensive and requires a special tool called the charging pipe, part number KV311039S0 (Figure 4). The charging pipe screws into the check-level overflow pipe area. This will require the ability to pump fluid up into the transmission from this location.

Figure 1 Figure 2 Figure 3 Figure 4

One work around that has been used by others is to locate an accessible speed sensor on the transmission such as the OSS on the CVT7 transmission (Figure 5). With the sensor located in the common sump part of the case far above where the full level will be, its access hole can work well with filling the transmission. A word of caution here: there are transmissions that have bolts that appear to be fill plugs but are band anchor bolts. If you decide to look for a fill plug, be sure you know what you are unbolting first!

There is what appears to be a fill plug on this CVT7 just above the pan, as seen in Figure 6. Looking from the inside with the pan in place (Figure 7), you can see that the overflow pipe is taller than the plug opening. This location will get fluid in the transmission but you would still need to top off the level through the overflow pipe or elsewhere from a higher point.

Figure 5 Figure 6 Figure 7

The fill process begins by attaching a scan tool to the vehicle so the transmission fluid temperature can be monitored. The next step is to pump 3 liters into the transmission. Start up the vehicle and pump in another three liters. Place the transmission into gear and hold for 5 seconds before returning the selector lever back to Park. Top off with approximately 0.9 liters of fluid until it begins to run over the check level or overflow pipe. Then wait until temperatures have reached 35°C (95°F) to 45°C (113°F) and check again and adjust accordingly. When completely full, a very thin stream of fluid slowing down to a drip should be seen.

Although this was an example using a CVT7 transmission, it provides the basic concept of filling and checking fluid level with most other transmissions not using a dipstick.

Another example would be Toyota’s U660E transmission. This too has a drain plug and check level pipe in the bottom pan similar to the CVT7 transmission (Figures 8, 9 and 10).  But this transmission does have a designated fill plug high above on the year cover (Figure 11). It has the letters WS on the plug, identifying the type of transmission fluid it uses.

Figure 8 Figure 9 Figure 10 Figure 11

Just as with the CVT7, a scan tool can be used to monitor transmission fluid temperature for proper level checking. They also have a manual method, which is done by jumping the ALDL connector with an optional Special Service Tool part # 09843-18040 (Figure 12).

The ATF fill procedures without the scan tool as provided by a factory manual are as follows. It also includes why Toyota has chosen to eliminate the dipstick method.

The ATF filling procedure is changed in order to improve the accuracy of the ATF level when the transaxle is being repaired or replaced. As a result, the oil filler tube and the oil level gauge used for a conventional automatic transaxle are discontinued, eliminating the need to inspect the fluid level as a part of routine maintenance.

This filling procedure employs a refill plug, overflow plug, ATF temperature sensor and shift indicator light “D.” After the transaxle is refilled with ATF, remove the overflow plug and drain the extra ATF at the proper ATF temperature. Thus, the appropriate ATF level can be obtained.

Service Tip

ATF filling procedure through the DLC3 Connector using Special Service Tool part # 09843-18040 is optional.

Recommended fluid temperature is 104°F (40°C) or less (Observed with scan tool or flashing D light without scan tool).

When a large amount of ATF needs to be filled (i.e. after removal and installation of oil pan or torque converter), perform the procedure from Step 1 below.

When a small amount of ATF is required (i.e. removal and installation of oil cooler tube, repair of a minor oil leak), perform the procedure from Step 6.

1) Raise the vehicle while keeping it level.

2) Remove the refill plug and overflow plug (Figure 10).

3) Fill the transaxle with WS-type ATF through the refill plug hole until it overflows from the overflow plug hole.

4) Reinstall the overflow plug.

5) Add the specified amount of ATF (specified amount is determined by the procedure that was performed) and reinstall the refill plug.

Service specifications

  • Procedure Liters (US qts, Imp.qts)
  • Removal and installation of transaxle oil pan (including oil drainage) — 2.9 (3.1, 2.6)
  • Removal and installation of transaxle valve body — 3.3 (3.5, 2.9)
  • Replacement of torque converter — 4.9 (5.2, 4.3)

Lower the vehicle:

6) Use the SST (09843-18040) or jumper to make shorts between the TC and CG terminals of the DLC3 connector (Figure 13).

7) Start the engine and allow it to idle. A/C switch must be turned off.

8) With the brakes applied, move the shift lever from the P position to the S mode position (Figure 14) and slowly selects each gear S1-S6 (Figures 15, 16). Then move the shift lever back to the P position.

9) Move the shift lever to the D position, and then quickly move it back and forth between N and D (at least once every 1.5 seconds) for at least 6 seconds. This will activate oil temperature detection mode.

Standard: The shift position indicator light D remains illuminated for 2 seconds and then goes off.

10) Return the shift lever to the P position and disconnect the TC terminal.

11) Idle the engine to raise the ATF temperature.

12) Immediately after the shift position indicator D light turns on, lift the vehicle up. The shift position indicator light D will indicate the ATF temperature according to the table in Figure 16.

13) Remove the overflow plug and adjust the oil quantity. If the ATF overflows, go to Step 16, and if the ATF does not overflow, go to Step 14.

14) Remove the refill plug.

15) Add ATF through the refill plug hole until it flows out from the overflow plug hole.

16) When the ATF flow slows to a trickle, install the overflow plug and a new gasket.

17) Reinstall the refill plug (if the refill plug was removed).

18) Lower the vehicle.

19) Turn the ignition switch (engine switch) OFF to stop the engine.

Figure 12 Figure 13 Figure 14 Figure 15

In reading through the procedures by Toyota, it is interesting to note the placing of the selector lever in the S mode as explained in Step 8. With the brakes applied 1, 2, 3, 4, 5 and 6 gears are manually selected. The idea is to charge as many of the hydraulic circuits as possible before checking the level. Lexus has an automatic 8-speed transmission called the AA80E with nearly the exact same fill procedures. It too uses the S mode to tap up and down through all 8 gears.

Whether the elimination of the oil filler tube and the oil level gauge is to provide improved fill accuracy or not, this method is here to stay. I have seen many shops adapt to this change effortlessly with ingenious methods to pump the fluid into the transmission. The one that amuses me the most is using a 1988-89 Honda power steering pump speed sensor assembly as seen in Figure 18. One shop I have visited mounted this pump and motor on a cart with a car battery below as seen in Figure 19. Quite ingenious and it gets the job done, pumping the fluid into the transmission easily. 

Figure 16 Figure 17 Figure 18 Figure 19

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