Q: Transmission

asked by on January 09, 2017

I just filled my transmission with fluid it was running great then the check trans light came back on its full it doesn't want to switch in to hear once I hit 65 what is the problem
My car has an automatic transmission.

Transmission Fluid Service $140.08 - $502.73 Get a Quote

This may be a sign of low transmission fluid or a faulty transmission control solenoid. As you know, 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. When this is faulty or not working properly, this can cause a delay in gear shifting or in some cases cause the car to not shift at all. This type of problem is amplified any time the transmission is low on fluid creating a drop in hydraulic pressure. 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 controls 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. I would recommend having a professional from YourMechanic come to your location to diagnose and inspect your transmission.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing


Experienced Mechanic?

Earn up to $70/hr

What others are asking

Car clicks upon startup, won't start.
You should have the battery load tested. It may not have enough power to turn the starter. If the battery is found to be good you should test the starter and make sure you're getting power to the coil when...
Motor replacement.
Hi there. It is hard to say if you need a motor without knowing what occurred. If the engine made any noise or suddenly stopped and will not crank or start then there are some tests that need to be...
Horn keeps on going off
Hello. There are a couple of reasons why your horn keeps going off. It is possible that one of the horn contacts is stuck or making contact in error. It is also possible that there is an issue with your...
Car starts, but dies.
I think you probably have a bad alternator. If you car starts, it's not the ECU. It could be the mass air flow sensor(MAF) but that has already been eliminated. You could have a clogged fuel filter which means it's...
Truck will start but dies 2 seconds later
Hi there. You are on the right track. This sounds like a fuel pump (https://www.yourmechanic.com/services/fuel-pump-replacement) problem. Though there are other things that can cause this, the series of events that you mentioned are the most likely causes. I would test...
Number #1 cylinder misfire?
Hi there. As you already know, replacing components without proper diagnoses can expensive and time consuming without resolution. Assuming, the engine is mechanically sound, good cylinder compression and valve train properly opening and closing, circuit tests need to be performed....
Flickering dashboard lights, total light outage that comes right back on. Burning smell in car.
You may want to find a local repair shop that specializes in electrical issues. While I can't say if you actually had a fuel pump issue, I doubt the fuel pump is related to the lighting issue and burning smell....
Car Won't Start
Hello. From what you describe it would appear that your vehicle is having some sort of malfunction with the security system. It may be possible that the security system is enabled and preventing the vehicle from starting. This may or...
Possible clutch slipping
As you know, the clutch transmits engine power to the gearbox, and allows transmission to be interrupted while a gear is selected to move off from a stationary position, or when gears are changed while the car is moving. Most...

Related articles

Isuzu Certified Pre-Owned (CPO) Car Program
Drivers Drivers who have been shopping for a used Isuzu vehicle may have already considered a Certified Pre-Owned, or CPO, vehicle. CPO programs allow owners of used cars to drive with confidence, knowing that their vehicle has been inspected and...
P0666 OBD-II Trouble Code: PCM/ECM/TCM Internal Temperature Sensor Circuit
P0666 means that a circuit failure has caused a potentially catastrophic overheating condition in a sensor due to defective or shorted control module.
Understanding the Isuzu Oil Life Monitor System and Service Indicator Lights
Car symbols, or dashboard lights, are a car service reminder. The Isuzu Oil Life Monitor system indicates when and what service your car needs.