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post #1 of 10 (permalink) Old 12-10-2003, 04:46 PM Thread Starter
 
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speedometer fluctuations

I have a '95 LX with a 4.6. The speedometer, for some reason keeps doing a wierd fluctuating thing. It will be showing the speed fine, but all of the sudden it will jump about 20 miles over what I'm going, then fall back to what I'm actually doing. I know i'm not actually changing my speed because I can have cruise control on and it will do that, my rpms remain constant, and I can't hear any sort of shifting sounds or engine noises out of the ordinary. Anybody know anything about this that might help? Thanks!
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post #2 of 10 (permalink) Old 12-10-2003, 07:18 PM
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if your speedometer assembly is bad, i have one for sale. let me know.

this belongs in interior.

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post #3 of 10 (permalink) Old 12-10-2003, 08:57 PM
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Someone correct me if i'm wrong. It seems to me that the cruise controll monitors the car's speed from the same sender that the speedo uses. That would tend to point to the speedo meter as being bad (or the circuits between it and where the cruise is read from). Or another thought, have you tried cleaning the connectors on the back of the instrument panel?

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post #4 of 10 (permalink) Old 12-10-2003, 11:41 PM Thread Starter
 
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I'll try pulling my guage cluster this weekend and cleaning the connections. I seem to remember the guy who sold me the car mentioning it, but I didn't notice anything for a while and I pretty much ignored most of what he told me because his knowledge of cars is very lacking. My mistake I guess. Thanks for the help though!
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post #5 of 10 (permalink) Old 12-11-2003, 01:35 AM
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I think it's probably your speedometer assembly. It could be the VSS, but it seems that they usually either work right or not at all. (And sometimes will switch back and forth between the two.)

-------------------

Steve

Owner, 1990 Thunderbird SC, white w/ gray cloth
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post #6 of 10 (permalink) Old 12-11-2003, 10:25 AM
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I'd check both, see if you can find a friend with an MN12 that'll let you borrow their speedo head unit and their VSS to see which one it is before you put yourself through irritation, effort, and expense replacing functioning parts.

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post #7 of 10 (permalink) Old 12-11-2003, 09:46 PM
 
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If it seems to change based on road conditions the counterweight in the needle may have fallen off.
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post #8 of 10 (permalink) Old 12-12-2003, 09:42 AM Thread Starter
 
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Thanks for all the help. I have a couple more questions now though, regarding the replies. What is the VSS, and where is it located? I have a haynes manual, and looked in there but couldn't find anything regarding it. Also if the counterwieght on the speedometer needle has fallen off, would I need a new speedo, or can that be fixed, or is not a major thing and can be ignored? I haven't noticed it having to do with road conditions, but I might just not be noticing them. Thanks!
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post #9 of 10 (permalink) Old 12-12-2003, 09:50 AM
 
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If it's the weight all you need is a new needle assembly.
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post #10 of 10 (permalink) Old 12-13-2003, 01:33 AM
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If you are comfortable with getting under an elevated car and with making mechanical repairs, the VSS is very easy to change. It is located on the left hand side of the transmission, toward the rear. It is held in by only one bolt and there are two wires entering it. You just unplug the connector, remove tthe bolt, and then pull the sensor directly out. You will need to reuse the bolt and bracket that hold it in, and you will swap the plastic gear that is on the VSS but inside the transmission over to the new VSS.

Just be careful (make sure the car is safely elevated and stays put), slide under the driver's side and you will see what you need to do.

Just so you have an idea of what to look for, here is a pic:
http://www.smpcorp.com/buyersguide/images/SC37.jpg



You can see the bracket there. The plastic gear fits on the shaft at the left side of the picture. Simply slip it off the old one, and onto the new one.

By the way, I bought my VSS at www.RockAuto.com for $18.30 plus shipping. It should be pretty cheap at a Ford dealer or a parts store, but I usually find the lowest prices at RockAuto.

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