Transmission Solenoid: Symptoms & Replacement Cost

Modern automatic transmissions use pressurized hydraulic fluid to change gears. Every time a gear change is required, the car’s computer activates a transmission solenoid, which directs transmission fluid into the valve body to engage the correct gear. If one of these electro-mechanical valves fail, then all sorts of transmission problems can ensue. So let’s take a closer look at the shift solenoid, and the common problems associated with it.

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What Transmission Do I Have?

How Does a Transmission Solenoid Work?

As you’re going down the road, the car’s computer analyzes data being sent by vehicle speed sensors and engine speed sensors. Based on this information, the Engine Control Unit (ECU), or the Transmission Control Unit (TCM), executes the appropriate upshift / downshift by sending a signal to one of several shift solenoids. These transmission solenoids have a spring-loaded plunger inside, which are wrapped with wire. When this coil of wire receives an electrical charge from the TCM / ECU, it causes the plunger to open, allowing transmission fluid to flow into the valve body and pressurize the desired clutches and bands. When this happens, the transmission changes gears and you continue down the road.

The car’s computer can control the transmission solenoid in several ways. If the vehicle is equipped with a dedicated Transmission Control Unit, it can open or close the hydraulic circuit using a direct 12v signal. Or, the Engine Control Unit can control the solenoid’s plunger by turning the ground circuit on and off. A solenoid can be used to control a single gear or multiple gears, depending upon the complexity of the design.
Transmission Solenoid Locations

Symptoms of a Transmission Solenoid Problem

Solenoid A transmission solenoid can fail due to electrical issues, or dirty fluid that’s caused the shift solenoid to become stuck open / closed. Any change in the transmission fluid pressure can cause numerous problems, including:

Erratic Shifting – If you’re dealing with a failed transmission solenoid, the gearbox can skip a gear up or down, shift back and forth between gears repeatedly, or get stuck in a gear and refuse to shift.

Transmission Won’t Downshift – If the transmission will not downshift, one of the shift solenoids may have become stuck open / closed, preventing fluid from entering the transmission valve body to pressurize the correct gear.

Severe Shifting Delay / Stuck in Neutral – In order for an electronically controlled automatic transmission to shift gears, the solenoid must be able to regulate the fluid pressure to activate the appropriate gear. If the shift solenoid is receiving too much or too little electric current, or dirty transmission fluid has caused it to become stuck open / closed, gear engagement maybe become difficult or delayed, which can cause the transmission to act as if it is temporarily locked in neutral.

Because the solenoids are connected to a vehicle’s electrical system, the ECU will usually register an error code and trigger the check engine light if something goes wrong. If this happens, the transmission can go into limp / fail mode, where it will only engage second / third gear to limit the vehicle speed without immobilizing it.

The first thing that your mechanic should look at are the error codes. Using a scan tool, the technician can determine the source of the solenoid’s problem. It could be as simple as a bad ground, or as complex as a failed solenoid pack (a grouping of individual shift solenoids).

Transmission Solenoid Replacement Cost – Parts & Labor

In most cases, solenoids are located inside of the oil pan, connected to the valve body. Depending on what you drive, the technician may be able to replace just the failed shift solenoid. However in some cases, the solenoids come in these multiple unit packs so if there is a problem with one, the entire pack must be replaced. 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. A pack can cost $50 to $300.

TypeCost Range
Single$15 to $100
Pack$50 to $300
Labor$120 to $400
Total (Pack)$250 to $600

Solenoid Pack

Although it isn’t unusual for transmission shift solenoids to wear out over time, you can extend their life by changing your transmission fluid at the factory recommended intervals. This will clean out all of the dirt and sludge that builds up, and the fresh fluid will keep the plungers on the inside of the solenoids from sticking. If you don’t know what your vehicle’s recommended transmission service intervals are, check the back of your owner’s manual, or simply ask Google.

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Need a replacement transmission? Get an estimate for replacement transmissions and local installation. Look up your transmission model by vehicle make and model.

What Transmission Do I Have?


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Jeffrey McQuistion
19 days ago

1996 F150 4r70W AODE transmission. After driving a while the engine will start missing and backfiring. It will not go more than 30 mph with the pedal to the floor.

20 days ago

F150 3l3p transmission hard shifting 2004 model

20 days ago

F150 3l3p hard shifts

Lukas Crumbley
28 days ago

I have a 1996 Chevy Cheyenne 1500 2wd 4.3l Automatic transmission and I have put a used motor in it cause I forgot to check the oil in it one day well after that it seems like my transmission wants to fall out. Cause when I have to come to a stop mostly on small hill I have to put it in low gear meaning 1st gear well when I shift up to 2nd gear nothing happens no jolt or nothing but when I go from 2nd gear to 3rd there is a jolt and my truck takes off like it’s supposed then. Would be cause of a bad solenoid switch? Oh and I have changed the transmission fluid like 5-6 months I know I need to do it again.

1 month ago

i got a computer read out that said shift selenoid c was bad on my ford focus, so this weekend i replaced it, an since i had the pan off, i replaced A and B also, i waited 24 hours and put fluid in it, let the eng warm up shift it through the gears in my drive way, waited a bit and the little wrench came back on, and the check eng light. so i put it in reverse an backed it out of my driveway an it went fine, when i put it in drive, it wont go, when i put it in first, it wont go, before i replaced the selenoids the car would go through 1st and 2nd, but wouldnt go into drive

1 month ago

2003audi a4 only has reverse

1 month ago

My 2007 caravan is not going into reverse all the way ,but has that this noise, my forward drive is fine, my question is it a soleid problem?

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