1998 mercury sable.need to change vss,does this have to be done from underneath vehicle'am a little afraid of breaking exhaust bolts

1997 Mercury Sable LS VSS Vehicle Control Sensor ...

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Jun 1, 2012 - Uploaded by Trevor Harris
I am trying to replace my Vehicle Control Sensor on my 1997Mercury Sable LS 3.0 Liter. Here's the ...

Check the
Vehicle Speed Sensor The vehicle speed sensor (VSS) (Figure 43) 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. That same VSS signal is use for the tachometer as well !

I would check the V S S or v Vehicle Speed Sensor

• OPERATION
• TESTING
• REMOVAL & INSTALLATION

Print

OPERATION

See Figure 1

Fig. Fig. 1: VSS with connector and driven gear
The Vehicle Speed Sensor (VSS) is a magnetic pick-up sensor that sends a signal to the Powertrain Control Module (PCM) and the speedometer. The sensor measures the rotation of the output shaft on the transaxle and sends an AC voltage signal to the PCM which determines the corresponding vehicle speed.

TESTING

1. Disconnect the negative battery cable.
2. Disengage the wiring harness connector from the VSS.
3. Using a Digital Volt-Ohmmeter (DVOM), measure the resistance (ohmmeter function) between the sensor terminals. If the resistance is 190-250 ohms, the sensor is okay.

REMOVAL & INSTALLATION

1. Disconnect the negative battery cable.
2. Raise and support the vehicle.
3. Remove the catalytic converter Y-pipe.
4. Unplug the VSS electrical connector.
5. Remove the VSS protective heat shield.
6. Remove the retaining bolt from the VSS.
7. Lift the VSS out of the transaxle.
8. Remove the driven gear retainer and the drive gear.

To install:

1. Inspect the O-ring on the sensor and replace if necessary.
2. Install the driven gear and the retainer.
3. Place the VSS into the transaxle.
4. Tighten the retaining bolt to 36-53 inch lbs. (4-6 Nm).
5. Install the VSS protective heat shield.
6. Attach the VSS electrical connector.
7. Install the catalytic converter Y-pipe.
8. Lower the vehicle.
9. Connect the negative battery cable.
ehichle speed sensor.

Sounds like he is just going to reseal the pan it is very labor intensive and the price id about right as the exhaust has to be dropped down to access the pan and bolts plus the clean up of the mating services if you get it done demand he install the FELPO OS30717R they fixed the problem with the oem gaskets it cost a little more but well worth the money and no future headaches
johnie G
35yrs ASE Master

Hello wsarah03,

There is a Vehicle Speed Sensor (VSS) mounted on the transaxle, that is a good place to start. The VSS tells the powertrain management system when and how to shift the transmission and also gives the speedometer it's signal.

From your description that the speedometer quit working at the same time I would suspect the a faulty VSS.

Regards,
netvan

You're going to need to replace the harness.

On the transmission.

Removal & Installation 3.0L (Except SHO) To Remove:

1. Disconnect the negative battery cable.
2. Raise and support the vehicle.
3. Remove the catalytic converter Y-pipe.
4. Unplug the vehicle speed sensor VSS electrical connector.
5. Remove the VSS protective heat shield.
6. Remove the retaining bolt from the VSS.
7. Lift the VSS out of the transaxle.
8. Remove the driven gear retainer and the drive gear.

To Install:

1. Inspect the O-ring on the sensor and replace if necessary.
2. Install the driven gear and the retainer.
3. Place the VSS into the transaxle.
4. Tighten the retaining bolt to 36-53 in lbs. (4-6 Nm).
5. Install the VSS protective heat shield.
6. Attach the VSS electrical connector.
7. Install the catalytic converter Y-pipe.
8. Lower the vehicle.
9. Connect the negative battery cable.

This is what it looks like:

VSS with connector and driven gear

Here's the steps on getting to it and replacing it:

Removal & Installation

1. Disconnect the negative battery cable.
   
2. Raise and support the vehicle.
   
3. Remove the catalytic converter Y-pipe.
   
4. Unplug the VSS electrical connector.
   
5. Remove the VSS protective heat shield.
   
6. Remove the retaining bolt from the VSS.
   
7. Lift the VSS out of the transaxle.
   
8. Remove the driven gear retainer and the drive gear.
   

To install:

1. Inspect the O-ring on the sensor and replace if necessary.
   
2. Install the driven gear and the retainer.
   
3. Place the VSS into the transaxle.
   
4. Tighten the retaining bolt to 36-53 inch lbs. (4-6 Nm).
   
5. Install the VSS protective heat shield.
   
6. Attach the VSS electrical connector.
   
7. Install the catalytic converter Y-pipe.
   
8. Lower the vehicle.
   
9. Connect the negative battery cable.
   

first of all, the power steering pump doesn't stop working and then start working usually they are just bad. second of all it shouldn't take 3 hrs to change speed sensor, and last the vss could cause all symptoms, if the car has variable assist steering the speed sensor could effect this

Check the transmission fluid first. it sounds like one of the clutch plates is sticking.

If you shift into second after you've stopped, can you get the car moving?