Close

Signs You've Got a Bad Shift Solenoid

Mia Bevacqua
April 10, 2018

shift solenoid on valve bodyA shift solenoid integrated into a transmission valve body.

Signs of a failing shift solenoid  

These solenoids operate submerged in transmission fluid and fail primarily from repeated hot-and-cold cycling in this harsh environment. Mechanical failures can also occur. Shift solenoids will also just wear out over time, but getting your transmission serviced at the recommended intervals listed in your owner’s manual can help prevent them from sticking. 

If you notice any of the following symptoms of a faulty shift solenoid, get your car to a mechanic right away. Avoid any highway use and have it towed, if necessary. If you leave it unchecked, your transmission can get damaged, which will lead to a very costly repair bill.

The check engine light comes on: The TCM continuously monitors shift solenoid operation. If it detects a problem with one of the solenoids or the related circuits, it will send a request to the engine’s computer to turn on the check engine light.

Erratic shifting or shift slippage: The shift solenoids regulate the flow of hydraulic fluid for shifting. 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.

Transmission won’t shift gears: A faulty shift solenoid can prevent fluid pressure from activating the appropriate gear. As a result, the transmission may not shift gears or it may get stuck in neutral.

Vehicle stuck in limp-home mode: If the TCM determines there’s a problem with a shift solenoid, it may put the vehicle in “limp-home mode.” In this state, the transmission will be forced into second or third gear to limit your speed, and one or more warning lights will appear on the dash  

Get it diagnosed by a professional
 

How to fix the problem

Diagnosis is key when it comes to transmission problems, as various issues can cause similar problems. Trouble with wiring or sensors could be at fault instead.

A faulty shift solenoid should be replaced. In some cases, the solenoid is integrated into the valve body and isn’t serviceable. This means the entire valve body will need to be swapped out.

Some high-end vehicles also have the TCM built into the valve body. Replacement of these units can be pricey. After any of these repairs, the TCM may need to be reprogrammed.

» MORE: Get an estimate for your car repair

What does the shift solenoid do?

As you drive, the car’s computer determines which gear is optimal for your speed. The transmission control module (TCM) — the brains of the transmission — will send power to one of the shift solenoids in order to shift gears.

Inside the solenoid, there’s a plunger surrounded by a magnetic coil. When the TCM triggers this coil, the plunger moves, allowing pressurized hydraulic fluid to flow to certain parts of the transmission. This allows the transmission to shift into the desired gear.  

There are two or more shift solenoids inside your transmission. The solenoids are typically integrated into the transmission valve body. If one or more of them fails, you’ll likely notice a handful of car problems.

Mia Bevacqua

About the Author

Mia Bevacqua is an automotive expert with ASE Master, L1, L2 and L3 Advanced Level Specialist certification. With 13-plus years of experience in the field, she applies her skills toward writing, consulting and automotive software engineering.

2 User Comments

Sign in to comment
By , November 03, 2018
Hello, I have a 08 BMW 535i. My vehicle starts up but will not go in gear. When I manually put it in neutral it will reverse and go forward with a loud clicking sound. A import repair shop said the valve body needs to be replaced and or transmission replaced. 6500 repair job. He never mentioned anything about the solenoids you mentioned in your post. Not sure If I should trust his diagnostics and just tow it into a BMW dealer for more accurate information. Would you happen to have any suggestions or guidance for me? Thank you kindly MIA
By , December 03, 2018
Hi i have a problem with my 04 suburban. In order for it to change out 1st gear i have to get out of the gas to make it change gears. I need answers to help fix the problem. I have already change shift solenoid A it stills does the same thing. What should i do next?

Related Questions

See what others have asked about this, or visit the Questions page to ask your own question.
What should i expect to pay to repair a failed shift solenoid valve?
Where is the shift solenoid located and what does it actually looks like.