Shifting problems at high speed

ANSWER : Hi there. Transmission fluid should be flushed every 50,000 miles to help avoid issues like you are experiencing. So, it’s probably a good idea to have your transmission fluid flushed and filter replaced, as the obstruction of debris or worn out fluid can cause the hard to shift issue you’re experiencing.

ANSWER : My guess is that the overdrive relay or solenoid has failed. If either of these parts fail, your Volvo will not shift into overdrive. This is a very common problem on Volvos such as yours. A trained professional, such as one from YourMechanic, will be able to diagnose your shifting issue firsthand to determine if this is indeed the cause.

ANSWER : Hi there. It is very possible that the speed sensor or shift solenoid is the primary source of this type of issue with the first to second shift. However, a worn out torque converter or an obstruction inside the transmission hydraulic lines can also produce similar symptoms. Since you recently had the fluid and filter changed, it would expect the sensors as being the primary culprit. I would suggest having a professional mobile mechanic come to your location to complete a Check Engine Light inspection, as the code you offered is a specific GMC code that indicates a general transmission problem. The detailed CEL inspection will download the OBD-II codes that we need to accurately determine the source.

ANSWER : Hi there. Many electronically controlled transmissions are computer controlled. With that said, the input signals for the engine can have a direct affect on the transmission behavior. Do no rely on scan tool recommendations because it is just that, a recommendation and not a diagnosis. Think of the scan tool you witnessed as a tool to sell parts, nothing more. A capable scan tool provides more than codes; it provides live data to the technician to aid in the diagnosis. When the computer sees an operating condition that is out of specification it sets a code; it does not know what or why, but only that it is out of spec. The code leads the technician to the system that has the fault; it does not diagnose it. Before you do anything, have the battery tested. A bad cell or low state of health can wreak havoc on an electrical system. I suggest having a qualified technician perform an inspection to avoid replacing unnecessary parts. Your Mechanic has several technicians available that can assist you with a check engine light inspection and a car is shifting hard inspection.

ANSWER : What you are describing may be a result of a faulty speed sensor, potentially low transmission fluid or a even a faulty transmission control solenoid. As your vehicle travels down the road, the 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 upshifts and downshifts by sending a signal to one of several shift solenoids. These transmission solenoids have spring-loaded plungers inside them, which are wrapped with wire. When this coil of wire receives an electrical charge from the TCM / ECU, it causes these plungers 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 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. In some cases, the Engine Control Unit (ECU) can control the solenoid’s plunger by turning the ground circuit on and off. When this is not working properly, this can cause a jerking reaction, a delay in shifting or in some cases may cause the transmission to hesitate in shifting gears. I would recommend having a professional from YourMechanic come to your location to diagnose and inspect your transmission.

ANSWER : The blower not working is most likely due to a fault with the blower resistor. When you go to high blower speeds the A/C may disengage the compressor if the cycling switch cycles or the high pressure switch gets over pressurized, shutting the compressor off. The first thing to do is to get the blower working correctly then test the A/C pressures using A/C gauges. If you’d like to get this fixed, consider YourMechanic, as a certified technician can diagnose your A/C issue and fix it accordingly. Good luck.

ANSWER : Hi there. It is possible that your issue is caused by a faulty speed sensor or just an obstruction of transmission fluid that needs to be flushed. It’s probably a good idea to have a professional mechanic come to your location and complete a car is hard to shift inspection so they can determine what is causing this problem and recommend the right repairs.

ANSWER : The oil pump in your transmission is probably worn out. The oil pump produces the hydraulic pressure that the transmission uses to engage the forward clutch. As the transmission warms up and some of the clearances tighten up, there is just enough pressure to make it work, but soon it probably won’t work at all. If you haven’t changed the fluid and filter, you may be able to extend the life of the transmission some with that service, but eventually you will probably need to get an transmission or an overhaul. To get a hands on opinion, you can contact Your Mechanic They can send a technician to your home or office to check out your transmission problem and tell you for sure what it will take to solve your problem.