RPM goes up but it doesnt let me go above 20mph. overdrive light was flashing and it displayed "TRANS FAULT."
Yesterday the O/D light was blinking and it was displaying "TRANS FAULT" , today my truck wouldn't go above 10-20mph but the RPM would keep on going up while it stayed at 10-20mph. it stays like that but will drive normal for like a minute then it'll go back to the problem.
My car has 1236850 miles.
My car has an automatic transmission.
Experienced mechanics share their insights in answering this question :
Hi there. Your vehicle has most likely entered a Limp Mode, which tends to happen when a transmission issue is detected by sensors and the ECU. The only way to resolve this issue is to have a professional mechanic complete a check engine light inspection so they can download the stored error codes and hopefully pinpoint the source of this issue.
How to Identify and Fix Common car Problems ?
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Sounds like the transmission module has detected a problem, and prevented the transmission from operating normally (this it to help prevent any more damage to the transmission). You“ want to get this looked at by a repair shop, or transmission shop.
Low transmission fluid will cause the overdrive light to flash. Since the transmission overdrive is controlled by a solenoid, it`s activated by fluid pressure. When fluid pressure is low, the solenoid will be unable to activate the overdrive gear and flash the overdrive light as a warning.
Codes indicating transmission problems fall under the category of Powertrain or “P” codes. If your vehicle is throwing codes and the first three digits are P06, P07, or P09, it almost certainly indicates a tranny or gearbox problem.
Transmission Fluid Temperature Sensor (TFT)
The Transmission Fluid Temperature sensor measures the temperature of the transmission oil (AFT). Its primary function is to inhibit overdrive and converter clutch operation when cold.
If the transmission is shifting fine but will not go into overdrive, then it may have a solenoid failure or a pressure problem. A bad brake light switch can also cause this. I would typically start by checking to see if the brake light works. If they don`t or if they remain on, then I would replace the switch.
The output speed sensor is also known as the vehicle speed sensor in a vehicle. It transmits a signal to the transmission control unit, informing it of the vehicle`s speed. Failure of the speed sensor is a common reason for taking the car to the mechanic.
However, in general, it`s probably not a good idea to tow in overdrive because the transmission could overheat and cause damage.
If your overdrive is working, the engine speed should fall by 500 or more rpm without a reduction in the vehicle`s speed.
Performing a System Reset
Vehicles equipped with a Power button: Press and hold both the Power button (center of the volume knob) and the Seek Right button for 10 seconds. Vehicles not equipped with a Power button: Press and hold both the Volume Down and Seek Right buttons on the steering wheel controls for 10 seconds.
The OBD scanner shows the code P0720 when the PCM detects an Output Speed Sensor Service malfunction. If there is a problem with the output shaft or the circuit, or the engine and input shaft speed are at an RPM that is not in sync with the output shaft speed, the vehicle`s computer stores the error code P0720.
Some error codes specific to a faulty TCM include p codes: P0613, P0700, P0706, etc. Erratic Shifting – The automatic transmission relies on the TCM to shift smoothly. Unless your vehicle has a manual override option, and it is engaged, your car should be shifting effortlessly.
The relay is an electronic part that is located behind the dash, above the brake and gas pedals, and inside of the firewall. Without a functional overdrive relay, the overdrive switch won`t work, and the solenoid won`t activate.
Over time, dirt, debris and other tiny particles can accumulate in the transmission fluid, affecting its fluid properties. This can cause the vehicle to die when you shift into drive or reverse, allow a loss of power, transmission slip, rough shifts or even prevent the vehicle from shifting into gear at all.
Here are the top symptoms that your solenoids aren`t functioning properly: You experience delayed gear shifting and a sense of pulling or slipping when trying to shift between gears. The vehicle will not downshift as you slow down.
The P0720 code is a standard OBD-II trouble code that detects an issue with the output speed sensor circuit. The powertrain control module (PCM) relies on a signal from the output speed sensor, so that it can determine the correct shift strategy and send that information to the transmission.
The P0720 is an OBD code related to the workings and overall condition of the output speed sensor circuit. The Powertrain Control Module (PCM) in this particular circuit works by gathering a signal from the output speed sensor to assess and input the right shift strategy to the car`s transmission.
Removing a wheel speed sensor will disable ABS—and sometimes, stability control. If your car has a yaw sensor, you can unplug that for results. You can also try simply unplugging the ABS module, though that could adversely affect your car`s braking performance.
Occasionally, these sensors can fail or become faulty working intermittently sending inaccurate signals to the ECU. In your case it may be possible that the transmission is receiving a faulty signal from the ABS system.
When there`s no speed signal coming from the sensors, shifting of gears will be a problem because the powertrain control module won`t control them correctly. This will make the transmission not work properly. It will either shift more quickly or roughly than expected.
It`s not bad to drive with overdrive off and does no harm to the transmission. However, you will get worse fuel economy and have more noise at high speeds. There`s really no reason to leave it off unless you need to ascend or descend a steep hill. You can turn overdrive on or off at any time or speed.
Usage. Generally speaking, overdrive is the highest gear in the transmission. Overdrive allows the engine to operate at a lower RPM for a given road speed. This allows the vehicle to achieve better fuel efficiency, and often quieter operation on the highway.
Third gear either locks the transmission in third gear or limits it to the first, second, and third gear ratios.
Technically speaking, a direct drive is more efficient in top gear than an overdrive due to its ability to transmit power directly through the main shaft with minimal parasitic losses.
The GM 4L80E 4-speed overdrive transmission is the ultimate overdrive platform to suit virtually combination that requires the strongest overdrive transmission possible.
Relevant Questions and Answers :
the most relevant questions and answers related to your specific issue
RPM goes up but it doesnt let me go above 20mph. overdrive light was flashing and it displayed "TRANS FAULT."
ANSWER : Hi there. Your vehicle has most likely entered a Limp Mode, which tends to happen when a transmission issue is detected by sensors and the ECU. The only way to resolve this issue is to have a professional mechanic complete a check engine light inspection so they can download the stored error codes and hopefully pinpoint the source of this issue.
Battery light goes on when I start car then turns off, if I rev engine light comes back until rpms go down. Abs goes comes on/off
ANSWER : Batteries can die due to faults in the charging system so ideally a suspected "faulty" battery should be load tested before a decision is made to condemn it. The only exception to this rule is if the battery is already clearly "old" (greater than 5 years) but even then once you put a new battery in, as a replacement for a "dead" battery, you have to comprehensively check out the charging system. Diagnostic Trouble Code P0460 will result in disruption of the dashboard fuel gauge’s ability to accurately report your tank’s fuel levels. The fuel gauge readings may be erratic, or read somewhere off scale. Vehicles equipped with a low fuel warning light feature may also suffer from erratic low fuel warnings in the event of a code P0460. Unless the P0460 code has been reported alongside other trouble code, all of the vehicle’s essential systems should otherwise function normally. I would recommend that you request a check engine light diagnostic to first resolve the fault causing the P0460 code to set. The check gas cap light warning light could be due a faulty gas cap and/or small leaks in the EVAP system.
Abs light, emergency brake light, steering wheel assist light, engine light, EPC light, traction control light
ANSWER : Hello, thank you for writing in. The vehicle does utilize a lot of the same sensors for these systems. Are there any other codes that are coming up when this code appears? If so you will want to take these into consideration when processing the repair and making a diagnosis. The module may be bad, and replacing it should fix the problem. The lights should turn off once the main computer recognizes the new module and the sensors sync up. If you believe the sensors need to be cleaned you may do so. Do as minimal as possible to make sure you are not damaging the sensor or disrupting the wiring inside. A bad connection would make the lights stay on. With so many lights that are effected by the module being illuminated, the module is likely bad or does not have a connection. Check the connection first and then resort to replacing the unit. For more help with these electrical tests, contact our service department.
on a 1970 Lincoln mark iii Interior lights wont turn on and warning lights are very dim and doorlock button makes buzzer go on
ANSWER : Hi there. Although the electrical systems on older vehicles tend to be much simpler in design, in many cases, issues like you’ve described can be very tricky to trace. It could possibly be something as simple as an expose wire creating an electrical short or a faulty relay that is not completing an electrical circuit. I wish we can help you further, but the best advice I can offer is to have one of our mobile mechanics come to your location and complete an electrical problems inspection.
Dashboard lights flash and then go out
ANSWER : Hello there, thank you for asking about your 1987 Oldsmobile Toronado. This is something that would require first hand inspection for complete diagnosis. However, there is a technical service bulletin (TSB) that may pertain to your issue. The TSB is number 92-T-141A and it deals with erratic lighting and instrument cluster operation, as all as "System Problem" message as you’ve described. According to the TSB, this problem is caused by either a short on the data bus or a faulty component on the bus – possibly the body control module or instrument cluster itself. I recommend contacting the professionals at YourMechanic to diagnose your electrical problems and repair your Oldsmobile.
No dash lights, back right tail light is out, no parking lights. Brake lights work though as does head lights.
ANSWER : Hi there. In many cases, when you have electrical problems like you’re describing, it’s caused by multiple electrical component failure. It’s likely that a few electrical relays are not working; especially if you have systems that utilize the same components (such as your brake light and tail lights). I would recommend having a professional mobile mechanic come to your location to complete an electrical problems inspection first, so they can pinpoint what is damaged and recommend the right repairs.
Engine Light and AT light. Car goes into limp mode
ANSWER : Hello. Most of the time this is the result of a transmission failure. It is common for this transmission to have internal pressure problem which will cause these codes. It can also be a voltage problem so I always check that first. I check the voltage going to the transmission and if it is too low I repair that issue which is commonly the ignition switch. If the voltage is fine, then the transmission pressures need to be checked and it will more than likely need to be replaced. I would have a transmission specialist look into this.
My car won’t go past 35mph
ANSWER : Hi there. From the description you provided, your vehicle has problems with the transmission again. You stated it will not shift into 3rd gear again, like before the transmission was rebuilt. If the transmission is again the problem, it should be covered under warranty. It could be a faulty shift solenoid. The shift indicator not reading properly could be a faulty transmission position sensor. If this is an overall lack of performance issue, according to your last statement, then possibly you have a restriction in the exhaust system. I recommend having your vehicle’s problems inspected and diagnosed by a certified technician from YourMechanic.
