A/T - A40 Series O/D No Fourth Gear

TECHNICAL BULLETIN # 192

TRANSMISSION: A40 Series

SUBJECT: No 4th Gear

APPLICATION: Toyota

DATE: Nov. 93

A4O SERIES OVERDRIVES (EXCEPT A43DE)
NO 4TH GEAR

The following steps should be used to diagnose a no 4th gear condition.

STEP 1 Eliminate the overdrive cancel solenoid.

AS A TEST:




^ Remove the two solenoid '0' Rings.

^ Find an '0' Ring that is the same outer diameter as the original large '0' Ring but is thicker (Figure 1)




^ Install the solenoid using the thicker '0' Ring. Make sure you don't over tighten the solenoid bolts. The idea is to keep the solenoid lifted away from the case (Figure 2). This will eliminate the ability of the solenoid to prevent 4th gear. If the transmission still won't shift to 4th gear go to step 2 on page 4. If the transmission shifts to 4th gear, the problem is either...

The solenoid is not energized - Electrical problem on vehicle

The solenoid is clogged, restricted or otherwise defective - Replace solenoid

Too much solenoid feed oil - Continue Reading








If the solenoid is being flooded, it's usually due to crossleaks in the auxiliary cover (Figure 3). Flat sanding the cover and replacing the gaskets will usually fix the leak. If the problem is still there, reduce the size of the solenoid feed. The original feed hole is .033". This should be reduced to .028". Figures 4, 5, and 6 show the locations of the feed holes for various models.

Note
To reduce a hole a separator plate, it is a common practice to put a check ball over the hole (use a bushing driver or a C-6 low roller race as an anvil) then strike it with a hammer. Instead of using a check ball, try using a C-4 band adjustment bolt. It's like having a check ball with a handle on it.


[STEP 2] PRESSURE CHECKS




Use the chart to check line and governor pressure.

LINE PRESSURE RESULTS:




If line pressure is normal at a stall but high at an idle, check for a frayed T.V. cable or sticking throttle valve or the upper end of the cable housing pulled out of it's metal end. If all of these are good try drilling the T.V. balance hole to .040"-.050". (Figure 8)

GOVERNOR PRESSURE RESULTS:




If governor pressure is low, air check the governor circuit. When you do the governor air check make sure the pan is off so you can see any governor leaks on the valve body. The most common area for leaks are at the case where the sealing rings fit and at the governor plate. (Figure 9)