[themist73]

Today while driving my daily route 60 to 65 mph. fairly straight freshly resurfaced road my speedometer just zeroed out a few minutes. Later while still driving it began working again it did it several more times, what's going on? I can't really afford to take it to a shop and I am real hands on I can tackle most things. Is it old school graphite needed in the line? Or could it be a short or fuse issue? Or is it more computer chip? Please HELP! Thank you.

[smoothy]

YOu have an electrical problem... the speedometer is electrically driven. Unless you can read schematics and are familiar with vehicle wiring and familiar with how their computer systems talk to each other... it might be over your head. There is no speedometer cable on these.

[themist73]

Actual I am an amateur electrician in school for HVAC if you can point me in the general direction I can take it from there, and I thank you for your help up to this point.

[KISS]

On some cars there still is a cable to the speedometer which is still mechanical. You can have trouble with where the cable goes into the transmission, so yes, lubercation may do the trick.

Other cars may put the sensor on the transmission and dispense with the mecahnical cable.

In any event, for the engine computer to operate, it has to get pulses. Those pulses may be created at the instrument panel or at the transmission.

It might be a good time to check the transmission fluid.

[smoothy]

Civics and Acuras went to electrically driven speedometers in the mid 90's, forget the exact year.
As was mentioned this uses a VSS (vehicle speed sensor) on the transmission that produces 4 pulses for every 360 degree rotation ( I think by magnetic reluctance) you won't see it if you turn it by hand as that's too slow, yeah... I've tried before that's how I know. I would start with checking and cleaning the electrical contacts on that. Its on top of the transaxle between the starter and firewall. The VSS signal goest to the ECU under the passenge side footwell under a panel on the firewall. It also goes to the instrument cluster. If you can get a copy of the Service manual for your specific series civic it will have all the information you need. If you try to Google up the query (you will have to cut and paste or type the following words into Google

2002 honda civic manual .pdf

And look you will see several downloadable FSM's on the internet. It will have everything you need, including identifying the connectors. Honda actually has very good factory service manuals.

I didn't put any direct links but its self explanitory at that point.


You may need an oscilloscope to check signals, you can't do it with a DVM. I'm giving odds it's a loose or corroded electrical connection. Its possible to have that happen in 8 years particularly if you are in the Northern part of the USA that sees a lot of snow and uses salt.

[CaptainRich]

The speedometer is electro-mechanical in that there is a gear inside the transmission that is converted to an electrical signal (more reliable and easier to route through the vehicle).
That signal is carried to the speedometer and then re-converted into a mechanical signal by way of small servo motors on the Instrument Panel Cluster that move the speedometer needle.
If it is only working intermittently, your problem is most likely the drivers/servo motors are failing. That will most likely require repair or replacement of the cluster.