I have a lazy Speedometer, meaning that the arm is slow to respond to speed changes. It also stops at an inaccurate speed when traveling at a constant rate.


I'd like to fix this myself. I need to know:

What are the names of all the components related to the speedometer (in the engine and in the dash)
What is the most likely suspect for this problem?

and

Whether you know of any places I can find diagrams for disassembly and reassembly of these parts.


Thank you in advance

3/20/2012 2:41:02 PM

does it get stuck at 20mph sometimes?

my speedo in my civic was doing the same. if you search, some say its the VSS gear, but then you'd have a check engine light.

mine just happened to be the speedo itself. took the cluster out and swapped the speedo assembly.

fairly straightforward. 2 screws holding the cover in place. then 2-3 holding the whole gauge cluster in. unplug the connectors and you can take the cluster out. then just disassemble as needed.

i picked up my speedo assembly from craigslist. i searched nationwide since it was small enough to ship.

3/20/2012 3:40:30 PM

Quote :

"does it get stuck at 20mph sometimes?"

I thought this was another honda joke

Thank you for your help!


Yah know... what I really really want to know is the physics behind how the civic's speedometer works.


You have the needle, which is connected by a wire, right? what is that wire connected to on the other end? Is that end where it reads the actual speed? I assume it's connected to an axle or wheel to determine the revolutions per minute and then calculate the speed. Which axle or wheel is it connected? Or are they judging the speed on something completely different?

Excuse the ignorance.

Now that I think about it, the speed would be affected by the circumference of the tire, if they based speed on revolutions per minute

See where I'm confused?

[Edited on March 20, 2012 at 3:48 PM. Reason : .]

3/20/2012 3:45:00 PM

usually read from gear drive in transmission output, and tire diameter does affect the readout because of this - i.e. way bigger tires - speedo reads less than actual speed

[Edited on March 20, 2012 at 4:13 PM. Reason : -]

3/20/2012 4:13:22 PM

A little more specific, please


Is it a digital monitor with magnetic ticking or mechanical/physical read?

3/20/2012 4:26:44 PM

Quote :

"way bigger tires - speedo reads less than actual speed"

Is it adjustable or do you have to change the gauge every time you change the radius of your tire?

3/20/2012 4:37:54 PM

VSS gear.

3/20/2012 6:20:15 PM

I found this gem, hope it will help others reading the thread:

Quote :

"How the VSS works: The ECU, speedo, and cc supply a 5V-10V reference voltage, and the VSS provides a pulsating ground, the rate of which increases with the speed of the transmission. "

3/20/2012 7:12:12 PM

I found the jackpot

Quote :

"The Honda Speed Sensor's main purpose is to transmit speed data to the TCU, ECU, speedometer gauge and the cruise control unit. It is reading the frequency of a bobbin that is attached to upper casing that speeds past the pickup sensor. The bobbin is a cylindrical or spool-shaped coil or insulated wire, usually containing a core of soft iron which becomes magnetic when the wire is traversed by an electrical current. The faster the wheel spins, the faster the frequency the wheel magnet moves past the sensor thus the higher speed reading on your speedometer. The vehicle speed sensor counts the revolutions of the transmission output shaft. For a given vehicle, the Transmission Control Module considers a certain number of revolutions to equal a mile. A defective speed sensor can either set off the "S" light or fail to engage the cruise control, which also can affect other system controls. The result is that the TCU thinks the vehicle is running at zero speed from what it’s actually doing. The first thing you notice is an intermittent speedo reading then followed by a transmission error code after decellerating from a moderately high speed. The error codes will reset after every ignition off/on cycle. http://techauto.awardspace.com/vss.html "

[Edited on March 20, 2012 at 8:03 PM. Reason : .]

3/20/2012 8:01:33 PM

i would go the speedo route first. you may not need to replace it. from what ive read online, if the VSS is gone, a CEL will show.


have you tried hitting the dash and seeing if the speedo jumps around?

3/20/2012 11:28:50 PM

I would rip the stock speedo out, get a 50 dollar GPS, and call it a day.
The added benefit is that your Civic will then be able to exceed the 130mph top speed limit set by your stock speedometer. It should improve your 0-60 time as well, thanks to the removal of resistance due to friction of the speedometer needle.

3/21/2012 4:03:26 AM

I drove my CRX for 3 years using the tach and gear calculations

3/21/2012 11:57:18 AM

Quote :

"I would rip the stock speedo out, get a 50 dollar GPS, and call it a day. "

Wait... you can pass inspection without a working speedometer?

3/21/2012 8:34:08 PM

Your speedo is at 0 anyways when they do the inspection. So why should it matter (yeah try do drive it on but they aren't looking at your speed). As far as I know, you don't have to have it working. Now a messed up speedo could result in a messed up odometer and if you've lost track of miles it may show up as a red flag. Again, a messed up vss can trigger a CEL. And that will fail you.

3/21/2012 9:53:34 PM

Pay attention to the odometer and trip meter? are they gaining mileage normally?
If so, then the fault lies within the speedometer unit itself.
I have a 95 civic that has been doing the wonky speedo thing intermittently for about 3 years now, but the odometer has continued to work normally, even when the speedo sits at 0 for several weeks of driving.
Apparently this is a bit of a known issue on Hondas of this era, also had a 94 accord with the same deal.

I've got an extra speedo that I've decided against putting in mine around here somewhere... I'd be glad to send it to you for the cost of shipping if you want it.

The speedometer function is not checked for during inspection.

3/21/2012 10:39:11 PM

Quote :

"I've got an extra speedo that I've decided against putting in mine around here somewhere... I'd be glad to send it to you for the cost of shipping if you want it. The speedometer function is not checked for during inspection. "

That would be an awesome deal, thank you!

Is it new/used?
Have you tested it?
and are there any cosmetic damages?

lastly, can you upload a picture of the part?

Thanks in advance.

3/22/2012 2:08:11 AM

You're worried about cosmetic damages of a speedo in your '94 civic? Worried about resale value?

3/22/2012 2:19:15 AM

damn this thread reminds me of dealing with craigslist buyers.

WTF. its a 94 civic. we've told you what could be the problem. hoss is pretty much giving you a free speedo. take it. try it. if it doesnt work. FUCK IT.

3/22/2012 1:05:56 PM

Thank you for your concerns.

3/22/2012 1:47:06 PM

Quote :

" thanks to the removal of resistance due to friction of the speedometer needle."

Very true, I put a carbon fiber speedo needle in my 93 accord and gained about .4 seconds on the quarter mile.

3/22/2012 1:50:21 PM

So I've looked all around my garage and junk shed for that damn cluster... it seems to have escaped. Hell, I may have trashed it or something a few years back. If I do find it I'll let ya know.

Also:
Is it new/used?
used

Have you tested it?
nope. but I recall getting good vibes from it.
plus the guy i bought it from pulled it from his wrecked hatch and promised it worked perfectly

and are there any cosmetic damages?
there weren't the last time I saw it. roughly 5 years ago.

lastly, can you upload a picture of the part?
when/if i find it i will be glad to.


That said, It is a shitbox 18 year old civic. don't be too high and mighty here.
The only reason I haven't put the cluster in my 95 is because I got used to driving by RPM/Gear calculations and decided it not worth the very limited effort to swap it out.
Plus, I'm getting proud of my odometer as it reaches 300k

3/27/2012 6:23:53 PM

I will admit that the civic is a P.O.S, but it's a civic that I just bought for <$800 and is worth $2000 and I could probably sell at $3000 if gas prices go to $5 this summer.



I'm just going to go to the local junkyard, craigslist, or ebay to find one. It's not a problem

If you find it in less than 7 days, shoot me a PM



Thank you so much for the generosity, it has been duly noted

3/28/2012 1:02:58 AM

I'll keep you posted.

No disrespect for the civic either-
I know exactly where you're coming from... I had a guy come up and wave $2500 in my face for my ragged out pile a couple of weeks back.
I almost took it, but decided I wouldn't be able to find another equally economical and reliable shitbox for that much.
I would end up spending all that and more on additional fuel expense if I were to drive the Marauder and F350 all year.

Best of luck with your project!

3/28/2012 7:41:46 AM

Quote :

"Again, a messed up vss can trigger a CEL. And that will fail you."

it's a 94. missing lights, horn, bald tires, and wiper blades are all he's on the hook for

3/28/2012 10:28:34 AM