can anyone please tell me where the vehicle speed sensor is. I looked a little and couldnt find it for the life of me. I need help real quick. thank you

 

Hi

Look near the rear of tranny. Elect. harness goes to sensor which goes into tranny. Sensor can be removed.

Good luck...OT

btw....a "Haynes manual" will help alot.

 

I always thought the vehicle speed sensor was the one that threaded into the differential housing. It picks up a signal on the tone ring on the diff. carrier (in the axle assembly) to project the speed of the vehicle & communicate with the ECM to control the ABS.

 

Hold up wait a minute...

First it depends on what year it is and what you are trying to do. Only the 97 and 98's have the VSS, 99 and newer is controlled by PCM and requires reprograming to correct. If it's correcting the speedo, shift points, etc on a 97/98 that is the VSS (vehicle speed sensor) that is located in the driver side rear tail housing of the tranny. It's small sensor near the top held in by one bolt with a harness going to it.

What gearman is referring to is called the ABS speed sensor (in my books). It is on the top of the rear diff. It reads the speed to control the lock-up functions for the ABS.

Both are easy to test or replace.

 

KYFordFreak - you mentioned that 99+ vehicles don't have a VSS. What type of sensor does the ECU use to get feedback on how fast the truck is traveling?

Thanks.

 

Yes, the 99+'s do not have a mechanical VSS, that takes the speed reading. I think the speedo cluster in the 97/98 are a hybrid type (mechanical/electrical). Tamkes it's reading and sends it via a voltage signal.
The 99's and newer are digital/electrical. As for as how they take the reading I am not sure. I would say if you do a search it would be easily found, maybe in the tire and wheel section. I would assume it takes it from the tranny still or maybe the rear diff.

 

Hi

My 99SC with a BD 11/98 has the "VSS" installed in the rear tail shaft of tranny. Yes, remove one bolt and harness to remove.

Now as KY mentioned...got me to thinking... So 99SC "VSS" is electrical/electronic in nature. Old technology...an actual enclosed spinning cable was used to turn speedo. for mph.

I do have the digital "ODO" when in test mode...shows rpms. So to me that indicates this pickup signal goes thru PCM to speedo?
Not really sure? JMO!

Good luck...OT

 

Old Timer
You are right, old tech (pre 97 and maybe before that) is the cable driven speedo. 97 and 98 and I guess some 99's use the VSS and a electrical signal.

Now for the 99+'s it still has to pick the signal up somewhere put it gets sent to PCM. You are right about the digital tach coming from the PCM, too. No sure on how this system works. Can someone help us?

 

For F150 late model 99's and newer.

output shaft sensor (OSS) Located at the Driver's side Tailpiece of the 4R70W/4r100/M5r2 transmissions and used for the Shifting, etc on the Automatic transmission. Also used on the Manual M5R2 transmission. Input is on PCM's Pin #84 a Dark blue with a yellow tracer wire.

Turbine Shaft Speed (TSS) Sensor, used in conjunction with the (OSS) for 4R100 transmissions.

vehicle speed signal (VSS) computed and massaged from the (OSS)signal in the PCM and output is on PCM's pin #68 a Gray with a Black tracer wire. Used for Vehicle's speed control unit, etc.

The Cluster odometer/speedometer readout is multiplex'd on the communications data highway (SCP network) and handled by the microprocessor in the cluster unit.


Transfer Case Speed Sensor is used for the 4-wheel drive vehicles.
Hope this helps out.

 

wfstewart - thanks for the info. To make sure I am understanding correctly, the 99+ use a VSS?

On my '98, I know that the VSS produce an A/C signal. Do you happen to know if the OSS sensor produces an A/C signal as well?

Thanks

 

The resistance of the (OSS) sensor is between 344-759 ohms and it sends a frequency signal (variable reluctance) on this HALL TYPE OSS.
Between the OSS+ and PWR GND the voltage should rise above 5.0 volts and fall below 1.0 volts in a regular cycles

 

I think what he meant is that the vehicles speed is derived from the OSS sensor info by the PCM. It sounds like it's in the same place and may look the same but operate much different.

 

Yes, thats about the size of it.
In my previous post, I mentioned where to pick up the massaged VSS output signal from the PCM.

 

The one mounted on the transmission is the Vehicle Speed Sensor. The ones mounted on the wheels are Wheel Speed Sensors. It sends individual wheel speeds to the Anti Lock Brake System Control Unit to control the Anti Lock Brake System activation.

 

You do know that this thread has been dead for over 7 years?