GM Convertor Lock-Up and the TCC Solenoid
GM Hydramatic transmission.
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There is a solenoid in your GM converter that causes the the torque convertor clutch (TCC) to engage and disengage. When the TCC solenoid receives a signal from the engine control module (ECM), it opens a passage in the valve body and hydraulic fluid applies the TCC. When the ECM signal stops, the solenoid closes the valve and pressure is vented, causing the TCC to disengage. This lets the torque converter lock in "gear" or unlock out of "gear." If you think of it in a non-technical way, the torque converter clutch does the same thing inside an automatic transmission that your standard clutch does on a manual transmission. If the TCC fails to disengage when the vehicle comes to a stop, the engine will stall.
Testing the TCC
Before attempting to diagnose converter clutch electrical problems, mechanical checks such as linkage adjustments and oil level should be performed and corrected as needed.
Generally, if you unplug the TCC solenoid at the transmission and the symptoms go away, you have found the problem. Sometimes this can be misleading, because you don't know for sure if the cause is a bad solenoid, dirt in the valve body, or a bad signal from the ECM. The only way to know for certain is to follow the diagnostic procedures outline below. If you follow the test step by step, you will be able to determine the exact cause of the problem.
Before You Test
These tests as outlined in the General Motors repair manual can be performed by a competent home mechanic, but proper care must be taken to perform the tests in a safe manner. That means the drive wheels must be raised off the ground and the engine and transmission run in gear. Support your vehicle with jack stands. NEVER run the vehicle in gear when supported only with a jack. Chock the drive wheels and apply the parking brake.
Test #1 (Regular Method)
Before you begin this test, use a test light or multimeter to check for 12 volts to terminal A at the transmission. Once you've done so successfully, you can proceed with the following steps:
- Raise the vehicle on a lift or support it safely using strong jack stands so the driving wheels are off the ground.
- Connect the alligator clip of your test light to ground. Unplug the wires at the case and place the tip of your test light on the terminal marked A.
- Do not depress the brake pedal.
- Computer controlled vehicles: turn on the ignition and the tester should light.
- All other vehicles: start the engine and bring to normal operating temperature.
- Raise RPM to 1500 and the tester should light. This indicates a successful test.
- If the tester does not light, replace the solenoid.
- If the tester does light, but the problem persists, take your car to a mechanic.
Test #1 (Quick Method)
Check for 12 volts to terminal A at the transmission Assembly Line Diagnostic Link (ALDL) as described at the beginning of the Regular Method, above. Most quick methods of testing can be done at the ALDL, which is the plug interface that your factory-like diagnostic tool plugs into. Barring that, the info is still accessible using leads from your test light. This will allow you to do most of the electrical checks from the driver's seat and save much valuable diagnostic time.
- Connect one end of a test light to terminal A at the ALDL.
- Connect the other end to terminal F at the ALDL.
- Turn on the ignition and the tester should light. Note: some transmissions, like the 125C, must shift to third gear before the tester will light.
- If the tester lights, you have 12 volts to terminal A at the transmission.
- If the tester does not light, then check for 12 volts by the regular method.
When to Head to the Shop
While the tests outline above can be performed by the competent home mechanic, additional tests recommended by GM require that the transmission be opened and the valves be physically inspected. I do not recommend that you do this. If your vehicle passes the above tests but the problem persists, then it's time to bring it to a shop and have the internal parts checked for proper operation.
When the torque converter starts malfunctioning, you may feel shuddering and even slipping in overdrive. You usually notice your car shuddering because it feels like it’s vibrating. Your car will vibrate even when you’re not going very fast. The shuddering makes the car lag and is very noticeable.
Where is the torque converter switch located?
The torque converter is located between the rear of the engine and the front of the transmission. The clutch creates a mechanical connection between engine and transmission.
Where is the clutch solenoid located?
► What Does a Torque Converter Clutch Solenoid do? Positioned between the rear of the engine and the front of the transmission is the torque converter. The torque converter is responsible for transmitting the engine’s torque and power to the transmission.
How do you know if your transmission solenoid is bad?
You may discover that the transmission will not shift out of neutral, as the solenoid is not receiving the proper signals or opening enough to shift the transmission. The gear shifts may seem rough or erratic, leading to a shaky or rocky feeling in the vehicle when you attempt to shift gears, accelerate, or decelerate.
How do you test a torque converter solenoid?
How do you test a TCC solenoid? The best way to test the TCC solenoid is to measure the OHMs and make sure its within a suitable range. If it is not, then simply replace it.
Where is the transmission pressure control solenoid located?
They are usually located within the valve body, the transmission control module, or the transmission control unit. In most cases, solenoids are installed inside of the oil pan, connected to the valve body of the transmission.
Can you replace torque converter without removing transmission?
The good news is, if it is just your torque converter that is having issues since it’s a self-contained unit, you may not need to replace or rebuild your whole transmission. Torque converters can be serviced or replaced as a single unit.
What does a lock up solenoid do?
Torque converter lock-up is engaged through a solenoid mounted inside the transmission. When the solenoid is energized it redirects the fluid flow back through the input shaft to put pressure against the clutch assembly allowing it to engage with the front of the torque converter.
How long does it take to change a torque converter clutch solenoid?
This job typically takes 2-4 hours to complete, and shop time is generally billed at $60 – $100 per hour. The average total cost to diagnose and replace one ranges between $150 and $400. Depending on the make and model of your vehicle, expect to pay between $15 – $100 for a single transmission shift solenoid.
How do you test a TCC PWM solenoid?
How much is a torque converter clutch solenoid replacement?
If the solenoid needs to be replaced, then it may cost you between $85 and $400. The individual solenoids only cost $15-$30, on average, but can be as much as $100.
What is a torque converter clutch solenoid circuit?
The solenoid moves a valve that sends pressurized fluid to the clutch circuit, engaging the TCC. When the clutch is disengaged, the torque converter allows the engine to rotate without stalling. While the vehicle is slowing and approaching a stop, the TCC’s application is undesirable.
How do you check a transmission solenoid?
Raise up the vehicle with a jack and place jacks stands at all four corners to support it. Remove the bolts that are securing the transmission oil pan with a ratchet set and slide out the pan. This should reveal the solenoid that is attached to the transmission body.
What happens if transmission solenoid goes bad?
a problem with one or more of the solenoids can cause a lack of pressure, resulting in hard, soft or delayed shifts. a failed shift solenoid can also cause transmission slippage, where your engine revs faster but the car stays at the same speed.
Where is the TCC solenoid located on 4l60e?
The 4l60e TCC Solenoid is located on the front passenger side of the transmission near the valve body.
What would cause a torque converter to lock up?
However, when the engine turns more slowly it causes the torque converter to slip, creating heat. Slipping reduces fuel economy and heat can damage the converter and the transmission. The solution is to lock the converter. Lock-up eliminates the slippage, which reduces heat and improves fuel economy.
Where is the solenoid?
The location of a solenoid can vary depending on your vehicle’s make and model. Most cars have their solenoids mounted right on the starter motors, connected to other “starter” components like the starter gear and starter control terminal.
Can you drive with a bad transmission pressure control solenoid?
The short answer is that, yes, you can usually drive a car with a bad shift solenoid. Fluid pressure control should continue to function in the gear with the working solenoid, but you should avoid putting any serious stress on the transmission — towing or drag racing — just in case.
Can a bad torque converter ruin a transmission?
A bad torque converter can damage a transmission. Bad torque convertors can lead to damage, overheating, friction, and transmission fluid degradation. If these problems continue, it can cause even more damage to transmission.
What kind of noise does a bad torque converter make?
Whining or rattling noise: When you drive your car for a long, you should tell when something is wrong by listening to the car noise. Likewise, when a vehicle torque converter fails, the car will give a bad torque converter noise–a whining or whining sounds like a power steering pump with little or no fluid in it.