Where is the speed sensor located . please be very specific.gauge in the speedometer works when it feels like it. i wonder if it's the speed sensor...

The sensor in the differential is for the ABS. Did you replace the sensor for the speedometer in the end of the transmission?
And is the check engine light on ?

Well, a broken speedometer can mean typically one of two things.

First, the actual gauge could be broken. If this is the case, it may be possible to replace just the gauge if you order an OE gauge, but more commonly, the cluster is a complete assembly and must be replaced all at once. The cluster itself, depending on complication may be rather expensive, but the real cost comes in the labor of disassembling the dash to get at the cluster.

The second option is that your vehicle speed sensor is bad or there is a problem on the line to the gauge. This can usually be acquired for a reasonable cost. The problem is in getting to it. It should be either mounted on the transmission case or the rear differential, but sometimes it can be almost inside the transmission and take a considerable amount of time to get to.

Year, brand, model would be helpful. You sure a speedometer cable is broke? If you have a newer car most of them have speed sensor(s). If a speed sensor is not working, it could be the problem with the shifting. Please rate my answer so I get points awarded.

The hesitates and misses is probably a chock problem, especially since when it warms up, it does great.

Since you weren't very specific on your indications, I thought a general troubleshooting guide might be helpful to you. But you might want to look on ebay for a shop maintenance manual for your vehicle if you plan on keeping it for awhile and doing your own maintenance.

This answer is applicable for many BMWs in addition to the one listed below.

Q

The tach and speedo work most of the time, but sometimes work sporadically.

A
Here is a write-up on the initial steps in tracking down a speedometer and/or tachometer problem.
Applies to: E23, E24, E28, E30, E32, E34 with speed sensor units mounted in the differential housing cover.

1) Speedometer - The speed sensor may be faulty. The sensor is mounted in the differential cover. Remove the harness plug and remove the sensor. Clean the sensor and measure the resistance (should be 0.0 Ohms). If there is any resistance higher than 0.0 (zero Ohms), replace the sensor. If the resistance reads correct, reinstall the sensor.

2) The wiring at the connector plug for the speed sensor (in the differential housing) may be faulty and corroded .... pull the boot back from the plug housing and inspect the wires and the pins.

3) The actual speedometer and/or tachometer head may be faulty. It may have a loose connection within it or a cracked circuit board.

4) The speedometer or tachometer head may be loose on the main instrument circuit board (do the gauges change or move if you smack the top of the dash, above the gauges?). Remove the instrument cluster and check the mounting of the speedometer/tachometer to the circuit board. See the attached issues of our Fast Times newsletter for assistance in removing the instrument cluster, on E30 3-series models (see the articles on replacing the PC board and replacing the odometer gears for info on the removal of the instrument cluster).

Fall 2005 Fast Times Winter 2004/2005 Fast Times
DIY E30 PC Boards DIY Odometer Repair


5) The plug that carries the impulse signal into the instrument cluster may have loose contacts. The plug for the speedometer signal is located on the driver's side of the back of the instrument cluster (on the E30 chassis). If you remove the lower dash trim panel (the one above the driver's knees), you can reach up and touch the plug. It is in a vertical position and has up to 26 wires in it. If you wiggle the plug, while driving, and the speedo comes & goes, you have loose contacts in the plug connection.

6) You may have a problem with the service interval PC board and it's NiCad batteries. If your oil change and service interval lights can not be reset (or will not stay reset for an appropriate time period), the PC board is likely faulty. This can affect the various gauges, including the speedometer and tachometer. If the PC board is faulty, I would suggest replacing it (after checking the other areas noted above). See the attached Fast Times newsletter article on replacing the service interval PC board.

In your specific case, I would suspect that you need to replace the service interval PC-board, if your service reminder lights can not be reset or do not stay reset.

Your Jeep doe not have a speedometer cable. The speed is calculated by the PCM ( vehicle computer) by input values that are received from the vehicle speed sensor. This issue is most likely not repairable by the average person without the proper scan tool required to do so.

Hi.

Problem is usually the speed sender failing when speed gets too high. In some case the speed gauge itself is damaged. In Mercury the speed sender is located in the transmission. The part is difficult to test without professional equipment. Repair is done replacing the speed sender. If that does not fix the problem, work on the instrument panel speedo.

Here location of the speed sender:

The Vehicle Speed Sensor located on the Transmission is malfunctioning or the connection is malfunctioning.
It is very easily removed and replaced.
The Vehicle Speed Sensor sends vital information for the Transmission to properly Shift. Because yours is malfunctioning, this lack of information is causing shifting problems.
I do not know if you have a Mechanical or Electrical (Gauges or Digital) Instrument Display. I also do not know if you have a 17 or 19 bolt transmission pan, nor what type of transmission you have (AX4N or AX4S) Nor if you have a Speedometer Cable (Mechanical Instrument will have Gauges=Cable).
The best thing to do is to check the connections of the Vehicle Speed Sensor. Unplug and check both sides of the connection for corrosion/oxidation. You can also take this sensor out of the transmission and clean the interior end; reinstall and recheck operation.
If this does not fix the problem, then remove and replace this snsor.
Take the Sensor with you to the auto parts store to compare the part you receive. You should know what tansmission you have and the number of bolts on the transmission pan, and whether you have an Electronic (Digital) Instrument Panel or Mechanical (Gauges) Instrument Panel on your dash.
Let me know if this helped, or if you have additional information or questions. Feel free to contact me at FixYa.com!

You have a bad "speed sensor". It's located in the transmission. Your speedometer and odometer are not cable controlled, they are electronically controlled by your speed sensor.

Does it hang out at 18-20MPH, regardless of your speed?
Mine did the same thing. The problem was an open circuit inside the gauge itself, and there's no repair for the parts. You'll need to get a replacement speedometer gauge, or simply buy a replacement instrument cluster.


If it's not doing the "20mph" thing, then it's possible that you just need a new engine speed sensor. This is located on the rear of the engine block, and is hard but not impossible to reach and replace.

One way to test is to set the car on cruise control when the speedometer is working. If the speedometer cuts out ,but the cruise is still able to maintain your speed, then the sensor is OK and the problem is the gauge. If the cruise control also cuts out, then the sensor is bad.

you need a new speed sensor located on the gearbox with 2 size ten bolts holding it on and a 3 pin connection going into it! heres a pic http://www.hondacivicrepairs.com/views/honda-civic-speed-sensor.JPG