When experiencing problems with your vehicle, some things are obvious, like a flat tire. Diagnosing other issues can be a bit more tricky. There are a number of different conditions that mimic transmission trouble and can lead an inexperienced technician to misdiagnose and recommend a transmission rebuild.
Protect yourself from this expensive and sometimes unnecessary repair by knowing what symptoms to look for, which ones can lead to misdiagnosis, and what questions to ask at the repair shop.
A faulty speed sensor can no longer transmit the speed of the vehicle to the transmission. When this happens, the transmission will automatically go into limp mode, allowing you to still drive the vehicle, although slowly, until you to reach the repair shop. Other symptoms include the transmission revving higher before shifting gear, engaging into overdrive late or not at all, brakes may feel harder than normal when coasting, the speedometer may behave erratically, or the check engine light may come on periodically.
The solenoid is a major component of the transmission, responsible for shifting gears. This part can be replaced in some vehicles by removing only the pan, avoiding the cost of a full transmission rebuild, or removing and reinstalling the transmission. However, there are certain vehicles that do require full removal of the transmission to access the solenoid.
Similar to the speed sensor, the temperature sensor, if it is reading too hot or cold, will trigger the transmission into limp mode. Other symptoms that could indicate this problem include poor fuel economy, black smoke from the engine, an engine that is overheating, and a check engine light.
Low Fluid Level
If the transmission fluid level is low and/or leaks, it can cause serious problems with gear shifting. If this is not corrected quickly, it can cause mechanical failure of the transmission and become an expensive repair. Any time you suspect a transmission problem, it’s best to have a transmission expert complete a service or flush instead of using a general auto shop. This will help ensure that you get a correct diagnosis for the problem.
Worn Engine Mounts
If an engine mount is worn or damaged, it can allow the engine to move and “slam” against the body of the vehicle when accelerating, making clunking or banging noises. Be aware–some repair shops could say the timing for shifting is off when the transmission really is ok. If the problem isn’t correctly diagnosed and fixed, it can quickly cause a lot of damage to many parts of the vehicle, including the transmission.
An engine misfire can lead to the check engine light turning on. There are many reasons that particular warning light can go on, and one of them is spark plug failure or engine misfire. This can create symptoms similar to a bad transmission, where it shudders during shifting.
Fuel Delivery System
When a vehicle won’t rev past a certain point, it can indicate a damaged fuel delivery system. However, sensors in the vehicle may monitor the accelerator of the pedal instead, leading to a misdiagnosis of transmission failure instead. If you hear a loud electrical clicking or whining when the engine is running, even at idle, chances are excellent the fuel delivery system is the culprit.
Restricted Air Flow
Air flow is critical for proper performance of a vehicle. A failure in the catalytic converter can cause an exhaust system restriction and lack of acceleration. This may be due to a constant rich fuel mixture, or antifreeze entering the combustion chamber. If the converter outlet becomes plugged, it will ultimately lead to a lack of power, causing misdiagnosis of a transmission problem.
If you are in the Denver area and have what seems to be a transmission problem, please contact us at Advanced Transmission Center. We can easily diagnose and make a proper recommendation for repair. Free towing is available if you aren’t able to drive to either of our two locations.