What i did was swap a t45 that i had rebuilt to replace the blown out t45 in my 96 4.6. We didnt know that the old speed sensor was a mechanical/electric speed sensor and now its a magnetic/electric speed sensor. I need to find out what it is that i need to do... is there a special plug i can put between the wire plug and sensor, switch to another ecm, or do i have to have it torn apart to fix the problem. Because first gear takes my speedo to 90mph and second takes it to 135mph, and at 3000rpm the revlimiter hits and shuts down the motor... im confused and dont knw what to do about it...
Speed sensor is going to fast!
- Thread starter shawnrodhe
- Start date
just up plug it. I had a gear driven one before I got my new trans and I ran in the same problem as you. Make your self a blocking plate and cover the hole on the trans and be done with it. Thats how mine is ya the speedo doesnt work but that what the tack is for just drive around and pace yourself off other cars to get and idea of mph/rpm.
fshawn50
Member
Just F Y I they kinda frowned upon mod's like you mentioned for that these are "not legal" I won't go into detail but this will affect other readings on your car? Just aword of advice
best to just fix it? hopefully wmburns might have some better advice?
best to just fix it? hopefully wmburns might have some better advice?driving without a speedo is dumb, ghetto, and illegal if it means the mileage doesn't get counted.
But it sounds like the OP has other issues besides the speedo sensor. Rev limiter at 3000 rpms? Has nothing to do with a speed sensor.
You probably need the VSS for your year ECU, as well as the proper speedo gear. I'd think you could take them of the old trans. But I've not done this, only looked up the issue on the internet just now.
But it sounds like the OP has other issues besides the speedo sensor. Rev limiter at 3000 rpms? Has nothing to do with a speed sensor.
You probably need the VSS for your year ECU, as well as the proper speedo gear. I'd think you could take them of the old trans. But I've not done this, only looked up the issue on the internet just now.
Speed sensor
Well i dont want to block it off, thats how i stay outta trouble lol... but before the trans was replaced, i had no rev problems, but they only happen when the speed sensor is plugged in, just no 4th gear, and an annoying bad grinding 3rd gear... well i can have the other rebuild, or put a new main shaft with the right gear in it... if you would have seen the trans fluid out of the old one, you would have liked to mak a pearl flake paint out of it! it was nice...
Well i dont want to block it off, thats how i stay outta trouble lol... but before the trans was replaced, i had no rev problems, but they only happen when the speed sensor is plugged in, just no 4th gear, and an annoying bad grinding 3rd gear... well i can have the other rebuild, or put a new main shaft with the right gear in it... if you would have seen the trans fluid out of the old one, you would have liked to mak a pearl flake paint out of it! it was nice...
wmburns
SN Certified Technician
It is not the rev limiter shutting you down. The PCM thinks the car is going 140+ MPH. It is the car speed limiter shutting the car down.
Would recommend getting fixed for the reasons already mentioned. In addition if not fixed will affect the PCM's ability to control radiator fan speed correctly. Likely will lead to overheating while stuck in traffic. For an auto car, even more important for the PCM to know the car's true speed.
I can say that there is a difference in the sensor between the 1996-1998 and 1999+'s. One uses a Vehicle Speed Sensor (VSS), another uses an Output Shaft Speed Sensor (OSS). Will research.
Salvage yard not likely to be a good option as the salvage yard will not part out a working transmission (will have to buy the whole unit).
>>From Ford Service CD
Output Shaft Speed Sensor
The Output Shaft Speed Sensor (OSS), provides the Powertrain Control Module (PCM) with information about the rotational speed of an output shaft.The (PCM) uses the information to control and diagnose powertrain behavior. In some applications, the sensor is also used as the source of vehicle speed. The sensor may be physically located in different places on the vehicle,depending upon the specific application.The design of each speed sensor is unique and depends on which powertrain control feature uses the infomation generated.
Vehicle Speed Sensor
The vehicle speed sensor (VSS) (Figure 44) is a variable reluctance or Hall-effect sensor that generates a waveform with a frequency that is proportional to the speed of the vehicle. If the vehicle is moving at a relatively low velocity, the sensor produces a signal with a low frequency. As the vehicle velocity increases, the sensor generates a signal with a higher frequency. The PCM uses the frequency signal generated by the VSS (and other inputs) to control such parameters as fuel injection, ignition control, transmission/transaxle shift scheduling and torque converter clutch scheduling.
Would recommend getting fixed for the reasons already mentioned. In addition if not fixed will affect the PCM's ability to control radiator fan speed correctly. Likely will lead to overheating while stuck in traffic. For an auto car, even more important for the PCM to know the car's true speed.
I can say that there is a difference in the sensor between the 1996-1998 and 1999+'s. One uses a Vehicle Speed Sensor (VSS), another uses an Output Shaft Speed Sensor (OSS). Will research.
Salvage yard not likely to be a good option as the salvage yard will not part out a working transmission (will have to buy the whole unit).
>>From Ford Service CD
Output Shaft Speed Sensor
The Output Shaft Speed Sensor (OSS), provides the Powertrain Control Module (PCM) with information about the rotational speed of an output shaft.The (PCM) uses the information to control and diagnose powertrain behavior. In some applications, the sensor is also used as the source of vehicle speed. The sensor may be physically located in different places on the vehicle,depending upon the specific application.The design of each speed sensor is unique and depends on which powertrain control feature uses the infomation generated.
Vehicle Speed Sensor
The vehicle speed sensor (VSS) (Figure 44) is a variable reluctance or Hall-effect sensor that generates a waveform with a frequency that is proportional to the speed of the vehicle. If the vehicle is moving at a relatively low velocity, the sensor produces a signal with a low frequency. As the vehicle velocity increases, the sensor generates a signal with a higher frequency. The PCM uses the frequency signal generated by the VSS (and other inputs) to control such parameters as fuel injection, ignition control, transmission/transaxle shift scheduling and torque converter clutch scheduling.
wmburns
SN Certified Technician
Attempting to research this issue. It appears the difference between the VSS and OSS is more than skin deep.
The VSS is driven via a worm gear.
The OSS uses a tone wheel that works much like the ABS sensor or the crank shaft position sensor. It is a magnetic style that never touches the shaft. Complicating matters for 2004+, Ford switched from 6 tooth tone rings to 24 tooth.
The documentation that I have access to does not give me enough information to positively help. However, it is likely that both VSS gear and the OSS wheel are pressed onto the final drive shaft. Further, these sensors are not part of the tail shaft as would be the case in an automatic transmission.
One source of documentation leads me to believe the sensors are actually in different places in the transmission. However, the diagrams and pictures are for other purposes and do not have the level of detail needed. It is also possible one my documents is for a different model of transmission.
It is likely that you have a bigger issue than first thought. Not sure if the OSS can be removed and a VSS gear installed in its place (I suspect so, just not real simple).
Some pictures of the two transmissions may provide some in sight.
I also looked to see if a Speedcal could be used. It looks like the Speedcal only works with OSS signals. A Speedcal is not needed for the VSS has changes are handled via a plastic gear change.
I haven't found a version of Speedcal that will convert OSS/VSS signals to the other format.
It may be advisable to contact a transmission expert. Perhaps the supplier of the re-built T45.
The VSS is driven via a worm gear.
The OSS uses a tone wheel that works much like the ABS sensor or the crank shaft position sensor. It is a magnetic style that never touches the shaft. Complicating matters for 2004+, Ford switched from 6 tooth tone rings to 24 tooth.
The documentation that I have access to does not give me enough information to positively help. However, it is likely that both VSS gear and the OSS wheel are pressed onto the final drive shaft. Further, these sensors are not part of the tail shaft as would be the case in an automatic transmission.
One source of documentation leads me to believe the sensors are actually in different places in the transmission. However, the diagrams and pictures are for other purposes and do not have the level of detail needed. It is also possible one my documents is for a different model of transmission.
It is likely that you have a bigger issue than first thought. Not sure if the OSS can be removed and a VSS gear installed in its place (I suspect so, just not real simple).
Some pictures of the two transmissions may provide some in sight.
I also looked to see if a Speedcal could be used. It looks like the Speedcal only works with OSS signals. A Speedcal is not needed for the VSS has changes are handled via a plastic gear change.
I haven't found a version of Speedcal that will convert OSS/VSS signals to the other format.
It may be advisable to contact a transmission expert. Perhaps the supplier of the re-built T45.
speed sensor
Thanks for the help, what im going to do is have the transmission pulled again, and have the right shaft installed with the nylon worm gear. i dont want to screw around and piss myself off... Plus now with the sensor unplugged, im having a hesitation in the throttle. I dont need to make it any more expensive than it already is. But luckily the sensor is mounted in the same spot, and the gear ratio is the same as the stock t45.
Thanks for the help, what im going to do is have the transmission pulled again, and have the right shaft installed with the nylon worm gear. i dont want to screw around and piss myself off... Plus now with the sensor unplugged, im having a hesitation in the throttle. I dont need to make it any more expensive than it already is. But luckily the sensor is mounted in the same spot, and the gear ratio is the same as the stock t45.
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