Drainback Test
1. Drive the vehicle for 30-60 minutes to attain normal operating temperature.2. Check the transmission fluid level. Add fluid only if required.
3. Drive the vehicle through 8 to 10 cycles of 1/2 throttle, 1-2 upshifts to elevate the transmission temperature. Then proceed as follows:
- Park the vehicle on level ground.
- Allow the vehicle to sit for 30-60 minutes.
- Check and note the fluid level on the fluid level indicator with the engine off, in PARK. The following example shows the fluid level after 45 minutes.
4. Allow the vehicle to sit for a minimum of 24 hours. Check and note the fluid level.
5. Subtract the reading taken in Step 3 from the reading taken in Step 4. Example: 38.1 mm - 6.35 mm = 31.75 mm (1.5 in. - 0.25 in. = 1.25 in.). If the fluid has risen 25.4 mm (1 inch) or more above the level in the first check, excessive converter drainback has occurred.
6. If excessive converter drainback has occurred, replace the drainback check valve at the rear case fitting and repeat the test.