I have a NB Miata with a non functioning Speedometer and Odometer.
I removed the vehicle speed sensor and re-soldered the wires since I already had it out, however the wires seemed to be intact. After soldering and resealing I hooked a volt meter to it and spun he gear. Voltage was produced, although how much voltage I couldn't tell you since it was a few days ago but it was in line with how fast I spun the gear.
Anyways put the sensor back in and speedo/odo still don't work.
Anyone have any ideas as to where I should look next?
Grounds and continuity. I've seen corrosion on the instrument cluster sockets in the past.
The system runs off frequency, not voltage. FYI.
I took out the instrument cluster last night and cleaned the contacts with contact cleaner they were pretty tarnished but are now shiny. Checked for continuity between the connector to the VSS and the dash connector there was continuity.
Re-installed everything, still didn't work. When I checked for continuity I checked the connector that plugs into the cluster but not on the cluster itself.
Is there somewhere I can check on the cluster itself? I would like to rule out a bad connection then work from there to determine if it is a faulty gauge or a faulty VSS.
Easiest way to check the cluster - do you have a friend with an NB? :)
Where are you located at, DrSmooth?
In reply to WonkoTheSane:
I am near Toronto.
In reply to Keith Tanner:
I get your drift! I don't know anyone with a NB but will ask around at the next race or Auto-x and see if I can dig one up.
Since I am a professional level procrastinator, it has taken a bit for me to get to the bottom of the problem. Hopefully the solution will help someone else.
I borrowed a gauge cluster to rule out the speedometer being dead, speedometer was still not working with the borrowed cluster.
Keith stated that it was a frequency and not voltage being generated by the sensor, so I did some further digging. The signal is some sort of Electro Magnetic Pulse, the frequency of which determines the speedometer reading.
Since there was continuity, I figured the sensor was at fault. I changed the sensor but the gauge was still dead.
The only thing I could think of was somehow, possibly? one or both of the wires had some sort of condition that allowed them to show continuity, yet disrupt the EM Pulse.
I ran a new wires, in this case the wires are orange and yellow at the cluster; orange with blue stripes and yellow with blue stripes at the sensor. Orange w blue corresponds to orange at the gauge, vice versa for yellow.
I changed the orange one first, then took the car for a quick spin. Orange was the culprit, since I had already fished two wires I changed the yellow wire as well.
An interesting thing happened after swapping the wires. I have an aftermarket heads up display connected through the OBD port. Prior to my speedometer malfunction, all the functions worked except the speedometer on the HUD despite my factory speedometer still functioning.
Since changing the wires, the speedometer feature now works on the HUD.
If the NB is anything like my NA, the ECU seems to get its speedo information from the cluster. Mine threw a check-engine light for speed sensor failure when my speedo cable broke.
While almost everything about the NB speedo is different from the NA, this routing of information is the same.
In reply to drsmooth :
Smooth, did you run the wire directly to the cluster from the VSS? I can’t fine a diagram I don’t have to buy that states where the wire runs from there. I keep seeing something about it going through the PCM. I’m having he exact same issue you had. Replaced VSS, no luck. After replacement of VSS, checked speed reading from an obd2 and no speed reading. Very intermittent jumping of the needle to ~10mph was shown on speedo and scanner but no constant speed reading, so I’m assuming it’s not the cluster. I either have another bad brand new sensor, or the wiring is bad. Oddly, car is a 2003 and has 72k miles, is garage kept and stays out of th rain...
