A check engine light coming on could signal an issue with your vehicle such as your emission system. To establish the exact cause of the problem, you'll need to run a diagnostic test with an OBD-II scanner and you may encounter P2017 code. The P0755 code indicates an issue with the shift solenoid B in the transmission in an automatic transmission.
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Where is the transmission shift solenoid located?
A transmission is made up of three separate systems that function together. The mechanical system, which includes input/output shafts, clutches, and gears, is responsible for transferring power from the engine to the driveshaft. The clutches are controlled by a hydraulic system that includes a pump and dozens of small fluid tubes and valves that determine which component of the gearset receives power. The vehicle’s computer, sensors, including the solenoids, which makes up the car’s electronic system, is responsible for regulating the hydraulic system's valves, dictating the transmission's shift points and hardness.
There are two sorts of electronic transmission systems: those that are purpose-built and those that have been adapted to incorporate electronic controls. A unique valve body — a set of fluid control tubes — connects to solenoid-controlled valves in retrofit transmissions. This type of transmission may still have limited hydraulic control over shift points and stiffness, but it's unlikely that yours does. Without its solenoids, more advanced, purpose-built electronic transmissions will function no better than you would without a central nervous system.
So where is the shift solenoid located?
Your automatic transmission's shift solenoids are housed inside the valve body. They are built within the valve body, and certain automobile models allow you to see them without removing the valve body, while others require you to remove the valve body.
An automatic transmission shifts gears by changing gear ratios inside a planetary gear assembly using hydraulic pressure. A solenoid is a small plunger-type mechanism that moves valves inside the valve body, allowing this to occur. When one of the solenoids fails, the ECU generates a P0755 diagnostic error code. Multiple shift solenoids are utilized in your gearbox to govern fluid transfer and flow from one circuit to another in order to shift gears.
If the P0755 code is detected, the computer has determined that the actual gear ratio employed differs from the gear ratio estimates based on engine speed, throttle position, and other factors. It's worth noting that some vehicles may need more than one erroneous operation to store the code.
How do I know if my shift solenoid is bad?
- Gear Shifts That Aren't Predictable
Unpredictable gear shifts are commonly observed when one or more of your transmission solenoids are failing. While travelling at a constant speed, your car may suddenly shift into a higher gear. As you can expect, this is a very stressful — and possibly hazardous — situation.
The solenoids open or close without receiving any input from the transmission computer, resulting in this shifting. This is frequently caused by faulty wiring within the solenoid. However, physical breakdowns can cause solenoids to open or close, making it difficult for the solenoid to maintain its precise position, whether open or closed.
These annoying gear shifts might occur in either direction. In other words, your car may jump to the next lowest gear at any time, causing your RPM to skyrocket. It could also shift into a higher gear. Your car may stall as a result of this. In any scenario, you must seek the assistance of a transmission specialist as soon as possible.
- Can’t Downshift
In rare circumstances, a defective solenoid can cause a gearbox to change from one gear to the next without issue, but the transmission will not shift back down. To put it another way, you won't notice any strange behavior while accelerating; only while decelerating will you notice it.
This common problem is caused by a solenoid that has been trapped in the open position. This could be the consequence of physical damage to the solenoid body or faulty wiring that prevents the solenoid from receiving electrical impulses. Another explanation could be that the solenoid is unable to shift into place due to foreign materials. This is frequently caused by contaminated transmission fluid.
- Shifting Time Delays
Pressure is the driving force behind an automobile transmission. In other words, a transmission's internal pressure changes are what allow it to shift from one gear to the next. The solenoids' movement is the only way to modify the pressure.
However, when a solenoid ages and breaks down, it exhibits a perceptible lag in carrying out the instructions that allow your transmission to shift gears. As a result, you may detect unsettling “gaps” between one gear and the next. As your sluggish solenoids struggle to migrate into their new places, it may feel as if your automobile has entirely lost power.
The transmission is the most vital and most expensive internal component of your car, second only to the engine. As a result, it's a good idea to familiarize yourself with the warning signals that anything is wrong with your transmission's solenoids.
How much does it cost to have a shift solenoid replaced?
Depending on what car you are driving, 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 at an average of $60 – $100 per hour. The average total cost to diagnose and replace one ranges between $150 and $400.
A single gearbox shift solenoid might cost anywhere from $15 to $100 depending on the type and model of your vehicle. A bundle might cost anything from $50 to $300.
Types and Costs
$15 to $100 for a single solenoid
Pack from $50 to $300.
Labor costs range from $120 to $400.
$250 to $600 total (package)
It is a fact that transmission shift solenoids are known to wear down over the years, you may help them last longer by replacing your transmission fluid at the factory recommended intervals. The new fluid will keep the plungers on the interior of the solenoids from sticking, and it will clean out all of the dirt and sludge that has built up. Check the back of your owner's handbook or Google if you don't know what your vehicle's recommended gearbox service intervals are.
What can cause a P0755 error code?
With the P0755 code, there are a variety of possible causes. These may include the following:
- A leak is indicated by a low transmission fluid level.
- Dirty transmission fluid
- An internal obstruction that prevents liquids from flowing properly.
- A malfunctioning shift solenoid
- Transmission internal mechanical failure
- Transmission fluid that has been tainted
- The ‘B' valve on the shift solenoid is faulty.
- The ‘B' valve harness on the shift solenoid is open or shorted.
- Poor electrical connection in the shift solenoid ‘B' valve circuit
- Issues with PCM or TCM
Symptoms of P0755 Code
You may encounter a variety of symptoms if the P0755 code is saved in your car's computer. These differ based on the severity of the problem and the vehicle's make and type. They may include the following:
The Check Engine Light is illuminated.
Failure to change gears
Failure to shift into a higher gear
Slipping transmission
Shifting in a harsh manner
Overheating of the transmission
Fuel economy has decreased.
“Limp-home” mode has been activated on the transmission.
How do I fix code P0755?
The replacement of the shift solenoid circuit is the most common fix for the P0755 code. Other fixes, on the other hand, could include:
- Changing out a faulty shift solenoid
- Adding to a low fluid level
- Changing soiled, burnt fluid
- A broken wiring harness must be replaced or repaired.
When dealing with a P0755 code, it is critical that mechanics complete all necessary diagnostic measures. It's a bad idea to assume that the code implies a problem with the shift solenoid itself. There are numerous possible causes, all of which must be ruled out.
Checking the level and quality of the transmission fluid is the first step in diagnosing the reason for the P0755 error. If the fluid level is low, it must be replenished before proceeding. If the fluid is unclean or polluted, it must be replaced before proceeding with the rest of the procedure. The mechanic will need to check the rest of the fluid in the drain pan if the fluid smells burned or contains shavings. Metal shavings indicate that the transmission has internal damage and may need to be rebuilt.
The mechanic will then connect the vehicle to an OBD II scanner to read the code as well as any other recorded data. After that, the codes will be cleared and the car will be driven to check if the codes will reset. If this is the case, the mechanic will inspect the shift solenoid, its wire harness, connections, and the shift solenoid circuit.
The most typical error here is to replace the shift solenoid when the issue is with the shift solenoid circuit. As a result, the owner's frustration grows as a result of faulty repairs. Checking the transmission fluid level and condition before replacing the shift solenoid is another mistake.
Will a Bad Shift Solenoid Throw a Code?
Your vehicle's on-board diagnostics system will display codes P0750 for a shift solenoid problem, P0753 for an electrical shift solenoid A fault, P0758 for an electrical shift solenoid B problem, and P0977 for a shift solenoid B control circuit problem.
Shift solenoids aren't cheap to replace, but they're not as pricey as a whole gearbox. Ignoring a warning light or code caused by a defective gearbox shift solenoid might result in major issues, such as driving in the wrong gear for your speed and conditions. Your transmission may then overheat and fail as a result of this.
The best method to tell is to look at your dashboard warning lights, which are usually a Check Engine or Transmission light. You might also find that your vehicle shifts slowly or refuses to move into higher speeds at all. Faulty wiring or shorts in your vehicle's electrical system might also create these problems.
In some cases, replacing the transmission fluid or flushing the transmission might free up a jammed shift solenoid, saving you money on repairs. Depending on whatever parts are malfunctioning, transmission torque converter replacement may be a possibility.
Though it may be tempting to try to fix a faulty shift solenoid yourself, it is recommended that you have the problem diagnosed and repaired by a professional. Why? Simply changing the shift solenoid will not solve the problem if the problem is in the wiring. To reach the solenoid, you'll need to remove the transmission fluid pan in most cases, and in certain cases, you'll need to replace the complete solenoid pack. At the same time, you'll need to replace the transmission filter and fluid.
Can I drive with a bad solenoid?
A vehicle with shift solenoid issues can typically be driven. Although it may not shift beyond a certain gear, you should be able to drive it for a short time without inflicting any severe harm. With the operating solenoid, fluid pressure control should continue to function in the gear, but you should avoid exerting any major stress on the gearbox, such as towing or drag racing, just in case. Of course, all of this requires that your transmission does not use a solenoid to engage first gear and that the first gear solenoid is in good working order. If it did, you'll immediately notice because the automobile won't move.
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The P0755 error code is a serious one. It is a clue that something is wrong with your transmission, even if it does not cause immediate driving problems. It is critical to have it identified and corrected as soon as possible to avoid further damage. Ignoring a warning light or code caused by a defective gearbox shift solenoid might result in major issues, such as driving in the wrong gear for your speed and conditions. Your transmission may then overheat and fail as a result of this.