The automatic transmission system in your vehicle uses a shift solenoid to engage and disengage the gears. Shift solenoid is controlled by an electric current that is supplied by the transmission control module. Learn how to test shift solenoid.
When the electric current is applied, it opens or closes a valve in the shift solenoid, which allows transmission fluid to flow into or out of the gear-changing mechanism.
There are two ways to test a shift solenoid: a multimeter or an ohmmeter.
1) Set the multimeter to the “resistance” setting.
2) Connect one lead of the multimeter to the ground terminal on the shift solenoid.
3) Connect the other lead of the multimeter to the “signal” terminal on the shift solenoid.
4) The multimeter should read between 0.5 and 2 ohms if the shift solenoid is working properly.
Transmission Shift Solenoid Function
The shift solenoids on a vehicle’s transmission control the fluid flow from the transmission fluid pump. This action controls the clutches and gears in the transmission. There are typically two shift solenoids, one for upshifting and one for downshifting.
When an electrical current is passed through the shift solenoid, a small plunger is activated and opens a valve. This allows transmission fluid to enter into the appropriate clutch or gear assembly. The result is a change in gear ratio which allows your vehicle to speed up or slow down as needed.
How to Test Shift Solenoids
1. Park your vehicle on a level surface and engage the emergency brake.
2. Locate the transmission fluid dipstick. With the engine off, remove the dipstick and wipe it clean with a lint-free cloth. Reinsert the dipstick all the way back into its housing.
3. Start the engine and allow it to idle for two or three minutes. Check the transmission fluid level again and ensure that it is at the “Full” line on the dipstick. If it is not, add transmission fluid as needed.
4. Place a drain pan beneath your vehicle before you begin any work on the transmission.
5. Locate the shift solenoids on your transmission. The shift solenoids are typically located near the firewall side of the transmission.
6. Disconnect the electrical connector from each shift solenoid.
7. Check each shift solenoid for debris or corrosion. If either is present, clean or replace the shift solenoid as needed.
8. Reconnect the electrical connector to each shift solenoid.
9. Add transmission fluid as needed until it reaches the “Full” line on the dipstick. Check the transmission fluid level again and start the engine.
10. Take a test drive and check for proper shifting. If the transmission shifts erratically or not at all, the shift solenoids may need to be replaced.
7 Symptoms of Bad Transmission Shift Solenoid
The following are the seven most common symptoms of a bad transmission shift solenoid:
1. Check the Engine light
One of the first and most common symptoms of a problem with the shift solenoid is the illumination of the Check Engine Light on the vehicle’s dash. The Check Engine Light will come on if there is an issue with the vehicle or even if there is an issue with the transmission itself. In order to find out what is causing the Check Engine Light to come on, you will need to have the vehicle’s computer scanned for codes.
Scanning the vehicle’s computer for trouble codes will often reveal the root cause of the problem. If the shift solenoid is bad, it will often set a code that says something about an electrical problem with the shift solenoid or a problem with the shift solenoid circuit.
2. Transmission Warning Light
Another symptom of a problem with the shift solenoid is the transmission warning light. The transmission warning light looks like a gear with an exclamation point in the middle of it. This light will come on if there is a problem with the vehicle’s transmission.
If the shift solenoid is bad, it will often cause the transmission warning light to come on.
3. Shifting delays
The third symptom of a problem with the shift solenoid is shifting delays. If the shift solenoid is not functioning properly, it may cause the transmission to take longer to shift between gears. This can often be noticed when accelerating or decelerating.
4. Skipping gears
Another symptom of a problem with the shift solenoid is skipping gears. If the shift solenoid is not functioning properly, it may cause the transmission to skip gears when pressing down on the accelerator.
5. Stuck in gear
Related to the above symptom, another symptom of a problem with the shift solenoid is getting stuck in gear. If the shift solenoid is not functioning properly, it may cause the transmission to get stuck in one gear despite speeding up or slowing down.
6. Downshift or Upshift problems
If the shift solenoid is not functioning properly, it may cause the transmission to have trouble shifting into lower gears when slowing down or higher gears when speeding up such as when trying to pass someone on the highway.
7. Limp mode
Last but not least, another symptom of a problem with the shift solenoid is the limp mode. Limp mode is when the transmission will only stay in one gear despite trying to shift into another. This usually happens when the vehicle’s computer detects a problem with the transmission and limits its operation as a safety feature to prevent further damage.
How to Diagnose a Shift Solenoid Problem?
In order to diagnose a shift solenoid problem, the first step is to check for transmission codes. This can be done with a simple code reader which can be purchased at most auto parts stores. Once the codes have been read, they will need to be diagnosed in order to determine which shift solenoid is causing the problem.
Transmission Shift Solenoid Replacement Cost
Depending on the make and model of your vehicle, the cost of a shift solenoid replacement can range from $300 to $800 on average. The cost will also depend on whether you need to replace just one shift solenoid or multiple-shift solenoids.
If you are experiencing any of the symptoms listed above, it is important to have your vehicle diagnosed by a professional as soon as possible. Ignoring these symptoms can often lead to more serious and expensive problems down the road.
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