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.
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.
Symptoms of a Transmission Solenoid Problem
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.
| Type | Cost Range |
|---|---|
| Single | $15 to $100 |
| Pack | $50 to $300 |
| Labor | $120 to $400 |
| Total (Pack) | $250 to $600 |
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.
Get a great deal on a replacement solenoid – for as low as $11 on Amazon <
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?
2012 Ram 1500 4×4 stays in 4th gear when stopped stays in 4th when you go. Put it in park turn off engine. Restart engine then it works normal. Then it happened again 2 months later, still works fine after restarting.
It doesn’t go in reverse
It won’t shift into 6th gear tell you go to neutral then back to drive once you do that the transmission works fine
04 dodge ram 1500 drive good for awhile than don’t pick up speed
Drive good for awhile than don’t pick up speed
When I start my 1990mustang 5.0 it jumps in to gear and and when I put. It in gear it takes a few seconds to go
The car stalls every time you come to a stop
The car stalls everytime you come to a stop
Mother in law just bought a 2004 Buick century fir $2000
120,000 miles
Never serviced.
I replaced the fluid and filter
Three months later solenoids fail during a cross country drive from Florida to NY
Did I cause this? She wants me to buy her a new gearbox.
The old fluid was pitch black. Likely factory original. The NY mechanic states it is low on fluid but I filled it up to full by dipstick.
2001 Honda accord. 82k miles. Check engine light came on. Check. P0740 analysis. Hesitation from park to drive. No other shift problems.
2001 Honda accord. 82k miles engine check light came on. Hesitation from park to drive. No other shift problems. P0740 checked with analysis.
I have a Acura TL 2004 , When I turn the car on the D light starts blinking , ABS , Check engine light stays on , when I drive it it starts off slow then it picks up like nothing but the D light is still blinking. They rebuilt a transmission in 10/28/21 for the car . When they computer checked it it read A&C Solenoid can you be the transmission going
2003 Dodge Neon in Limp Mode. Solenoid pressure sensor needs replacement.
Transmission solenoid needs replacement
I can’t shift to drive nor reverse and when I try too the car shuts off
4.02004grsndcherokeelaredoslippingtransmision
Slippingnoreversedometimesnothin
2010 Mazda 5 touring transmission in limp mode third gear only code u0101. What could be the problem.
Hi i have a 2012 chevy traverse with what appears to be having torque converter engagement and disengagement problems
from 4th gear on. it has a flair up on the 4-5 shift , also a faster than normal 5-6 shift with an occasional chug depending on throttle position .
At 60mph the tac fluctuates in lock up 1600 to 18-1900 RPM bounce .
I can command the TCC solenoid on with scan tool, and at 55 , 60 ,65 it doesnt appear to have torque converter slip.
It has no engine DTC’S , NO MISFIRES , NO Transmision Dtc’s , I’ve changed the dex6 ATF 4 times now which did improve the shift delay leading up to the above.
Valve body ? THCM?
No reverse when warm and battery drain when off
You figure it out I have a 04 tahoe that when warm won’t shift in any gear I need help
Sometimes when pulling out feels like it’s in overdrive 2006 Nissan maxima