Torque Converter Lock-up Issue
Many cars in the mid to late 1980’s were built with the 200R4 transmission because the 4th gear gave much better fuel mileage. The 200R4 is really a good transmission and can hold a large amount of power when built. It does have a few flaws that many people seem to overlook or never find a way to correct the issue. Since these cars had miles of vacuum hose, many blame it on a vacuum leak, but it is really just a $20 TCC solenoid.
Here Are The Symptoms
After a fair period of time driving in 4th gear (OD), the transmission seems to downshift late when slowing to a stop. This can cause the engine to stall or come very close to stalling. Once normal acceleration begins, the transmission will upshift early holding low RPMs and giving a very stiff feeling in the shifts. Inside the transmission, the torque converter’s lockup feature stays locked up in 2nd through 4th gears not allowing the engine to reach the peak torque output. When stopping, the transmission stays in 2nd gear until nearly stopping when it shifts into first gear unlocking the torque converter allowing the car to recover from a near stall.
In the cars with the 200r4 transmission, the ECM controls the TCC lock-up feature by grounding negative side of the TCC solenoid, enabling lock-up. Power to the TCC Solenoid is provided through a switch on the brake pedal that interrupts power when the brakes are applied. This is what causes the lock-up to disengage when the brakes are applied and the car is stopping.
The Fix is Easy!
Correcting the issue is not expensive and only takes an hour start to finish. The part numbers below are from the fix of our 1988 Monte Carlo SS. Sumit Racing has these parts in stock and is the easiest and most inexpensive place to get the parts fast.
- Transmission Control Solenoids TCS13
- ACDelco 12360654 Transmission Filter Kit
- 5 Quarts of Valvoline DEX/MERC ATF Transmission Fluid VV353
- ACDelco 08683502 4th Gear Pressure Switch
Shop Supplies & Tools
- Shop Towels in a Box
- 10mm, 13mm, 22mm, 26mm sockets
- Large catch pan for draining ATF
- Optional: Ingersoll Rand W1120 1/4″ 12V Impact Wrench
Watch the YouTube video to see exactly what everything will look like. There will be no surprises that way! Print this if you want to have instructions with you for the repair.
Block the rear wheels, parking brake on, and transmission in park.
Jack up the car to get the best access to the transmission. Use a lift to make it really easy.
Place the catch pan placed underneath the transmission oil pan, if your car is tilted to the front or rear, make sure the catch pan will get the oil in the right direction of flow. Remove most the oil pan bolts leaving one on each side of the pan. Remove the bolts in the direction of flow and try to catch as much oil as possible. Have rags ready. once it stops leaking, remove and dump the pan.
The transmission will continue to drip ATF while you work on the vehicle. We let the transmission drip for about 5 minutes while we cleaned up the pan, removed the gasket material and cleaned the magnet on the bottom of the pan.
The 4th Gear Pressure Switch (1 wire) and the TCC Solenoid (2 wires) are easy to see at this time as there are not many wires running through the transmission. Remove the transmission filter by pulling and rocking it back and forth. Be sure that the o-ring come out with the filter tube. If not, you will need to remove them from the pump bore with a screwdriver. Remove the TCC Solenoid using a 10mm socket, save the bolts. Cut the wires and splice in the new TCC Solenoid with the included caps. Wet the o-ring and replace the TCC Solenoid with the two bolts.
Remove the electrical connector lug from the top of the 4th Gear Pressure Switch. Remove the pressure switch using a 12 point socket or wrench. Replace it and not it is not tightly torqued (10 ft/lbs) using a torque wrench.
Install the new transmission oil filter using the old transmission fluid still dripping to lubricate the o-ring. Place the new transmission oil pan gasket on top of the pan and use a few of the bolts to hold the gasket in place during installation. Get all the bolts snug and tighten them to 12 ft/lbs. Do not overtighten as you can bend the pan and it will leak.
Remove the transmission dipstick and add 4 quarts of transmission fluid. Allow it to settle and start the car and shift it through the gears. Check the level in park and with the engine running. Ours needed the fifth quart to be at the top of the OK level.
This should correct your issue, so go out for a drive and enjoy your car feeling like new again!