speed sensor / speedometer drops too zero

[fburke]

1997 Escort


Every now and then while driving my speedometer drops too zero and stops working and it feels like my transmission is slipping. It only last for a few min then drives fine.

Today it did it again however the car drove fine even with the speedometer not working. After a few min my check engine light came on then it started again it only seemed like 1st gear was working it’s wouldn’t up shift. I checked the code and it was for a speed sensor.

I cleared the code and it seems to be ok now. I am just wondering is it just the sensor that needs to be replaced or could it something else in the transmission.

The car has about 118k on it and it’s our second car so I don’t want to put a lot of money into it.

Any suggestions?

[mightymoose_22]

Most likely just the sensor is worn.

[Davescort97]

You might clean the connections on the electrical connectiion to the speed sensor. This might cause it to work sometimes and other times not.

[Sandfobs]

I know that this thread hasn't been replied on since October 1, 2008 but I need to reopen this thread as it is identifying my problem.

1997 Escort


Every now and then while driving my speedometer drops too zero and stops working and it feels like my transmission is slipping. It only last for a few min then drives fine.

Today it did it again however the car drove fine even with the speedometer not working. After a few min my check engine light came on then it started again it only seemed like 1st gear was working it’s wouldn’t up shift. I checked the code and it was for a speed sensor.

I cleared the code and it seems to be ok now. I am just wondering is it just the sensor that needs to be replaced or could it something else in the transmission.

The car has about 118k on it and it’s our second car so I don’t want to put a lot of money into it.

Any suggestions?

My Escort is a 93 escort LX 1.9 litre it's not every now and then while driving my speedometer drops too zero and stops working and it feels like my transmission is slipping in and out of gear and it's everytime I drive it now. This thread talks of a speed sensor and I'm guessing the speed sensor is one of the modules attached to the throttle assembly. I've replaced the entire throttle assembly with the modules and it continues to do the same thing. It's getting very cold out now and I am desperately trying to fix this problem before winter is officially here. Need help.

1993 escort wagon LX 1.9 was sitting for the summer only use it in winter, last fall it died it was the timing belt, did not begin work until a few weeks ago. Work completed. so far replaced timing belt followed the book installation regarding timing marks. Replaced tensioner bolt and tensioner while at it. Replaced battery with new battery clamps. New gas tank, resealed fuel pump (no leaks), replaced disk rotors and pads, muffler change, and replaced alternator.

[Sandfobs]

Still no change in this problem. Speedometer gauge is not working at all now and the gears slip out of gear. Any suggestions greatly needed!!

[Davescort97]

It's all right to post an earlier thread if it is about an oncurring problem and isn't over 3 months old. The VSS (Vehicle Speed Sensor) isn't part of the throttle assembly and modules. It is part of the transmission. You may have to take the battery and tray out to get to it. It has an electrical connection going into it. There are several cables and hoses over the top of the area you want to work on. The wires from the oxygen sensor are clipped to the bracket of the VSS. Locate the oxygen sensor and trace its wires back to the bracket of the VSS in order to find it.

Since you used the first post to describe the problem you are having I'm assuming you have an automatic transmission. If not then the speed sensor wouldn't have anytning to do with the transmission slipping out of gear. Because the speed sensor isn't working the speedometer isn't working either. Because you have no speed registered on the speedometer, the transmission thinks you are stopped or going very slow and won't shift it out of first gear.

You need to replace the VSS, not to be confused with the TSS (Turbine Speed Sensor).

1. Raise and support the vehcle.
2. Disconnect the electrical connector
3. Unclip the heated oxygen sensor (HO2S) wire clip from the VSS bracket.
4. Remove the VSS bolt.
5. Gently pry out the VSS.

Judging from what you have already done you shouldn't have any problems. It's not a big job once you find it. It might be easier to go ahead and buy the part so you can identify what you are going to change. Dave

[Sandfobs]

VSS (Vehicle Speed Sensor) - Napa Auto Parts $120 YIKES !!!

I don't feel comfortable using this method but I contacted a local scrapyard and he said as long as the componant is fine it would be fine to use a scrap one, if it continues then it is not your problem but if it is and this one works it could work forever.

I personally don't like to use scrapyard electrical componants but I believe this is worth a shot to cut the cost and if it fails again at least I know where it is and I will buy the new one then. Opinions would be great. THx Dave you have been a great help.

[Sandfobs]

Update I found another escort at the salvage yard and replaced it with no real problems it started fine but no change speedometer it still reading 0 but it hasn't slipped out of gear it did have trouble getting out of first a few times. (((disappointed)))

[Sandfobs]

I think I will head down to the srapyard and try another one just in case then I suppose I will have to purchase the $100 part

[AzTumbleweed]

Is there a speedo cable or is this all electric? Could be a speedo cable if you have one.

[Selectron]

I don't have a service manual for the '93, so the '95 manual is the closest that I have. According to that, "the VSS rotates a cable and the instrument cluster generates a DC signal and sends the signal to the Powertrain Control Module (PCM)."

In the Engine Controls section of the manual, it also says that the VSS "Generates an AC signal that is proportional to vehicle speed. The PCM uses this speed signal to control fuel injection, ignition timing, etc." (I don't think that's relevant to your problem but I've included it for the sake of completeness).

Under the section for Instrumentation and Warning Systems, if the speedometer is inoperative, it indicates these tests:

=============================

K1 CHECK SPEEDOMETER CABLE


Check the connection between the speedometer cable and the speedometer.

Check the connection between the speedometer cable and the transaxle.

Are the connections in satisfactory condition?

Yes
GO to «K2».

No
REPAIR as required.

=============================

K2 CHECK SPEEDOMETER GEAR


Disconnect the speedometer cable from the transaxle.

Remove the speedometer gear from the transaxle.

Spin the speedometer gear.

Are there any broken teeth on the speedometer gear or is the speedometer gear binding?

Yes
REPLACE the speedometer gear.

No
GO to «K3».

=============================

K3 CHECK SPEEDOMETER


Remove the instrument cluster.

Spin the speedometer head counterclockwise.

Does the speedometer needle move while spinning the speedometer head?

Yes
REPLACE the speedometer cable.

No
REPLACE the speedometer.

=============================

As Tumbleweed said, the problem might be a broken or binding speedo cable. I'd pull the instrument cluster and spin the speedo head. If the needle moves, then I'd fit a new cable.

[Sandfobs]

Wow that's a great post Selectron I am pretty sure there is a cable it is an automatic 93 1.9 litre and I do have the book for it. I will pull the instrument cluster and inspect the speedometer cable. I hope this cable is the problem. Thanks for the posts.

[AzTumbleweed]

It would be easier to first unhook the cable at the transmission. Spin the cable with your fingers and see if the speedo moves. If the cable is broken you should be able to pull half of it out from here.

[Selectron]

Thanks, Tumbleweed, yep that makes sense as he's already familiar with how to access the transmission end of the cable, which is probably easier than pulling the instrument cluster. By the way, Sandfobs, if you do discover that the cable is faulty, the service manual reckons you can replace it without removing the cluster. This is the procedure:

Speedometer Cable


Removal

1. Disconnect the battery ground cable.

2. Disconnect the speedometer cable from the vehicle speed sensor (VSS) by pulling upward on the speedometer cable.

3. Disconnect the speedometer cable from the speedometer head by reaching up behind the instrument cluster and squeezing the speedometer cable retainer.

4. Disconnect the speedometer cable from the clip at the lower corner of the battery tray and remove the speedometer cable from the engine compartment.


Installation

NOTE:
Be sure to connect the speedometer cable to the speedometer head first or it may be difficult to engage the speedometer cable in the speed sensor.

To install, reverse the removal procedure.

Test drive the vehicle to check for proper operation.

[Sandfobs]

I will probably remove the instrument cluster anyhow as I would like to repair or replace the rear defroster anyhow.. I have read in the book the cable should be replaced but installed with white grease. I suppose I can just ask at the shop for white grease but here is my question is there more than one grease that can be used here? I do not want to use the wrong grease for some reason and give myself a big headache.