Hi all....
I did the square facia to round dash facia swap this weekend. I have the Tacho and all lights working .
But no SPEEDO
I have checked the cable and it is fine at both ends
Symptoms;
1) The needle sits LOWER than Zero km/h As in all the other (and my other) speedo needles seem to sit on Zero
2) The needle doesn't move at all - it doesn't twitch or jump
3) when spun backwards with the drill it seems to wind backwards

IS the speedo 'unwound' as in has it gone around 1x time already and wont wind further?
OR is there an electrical problem

I suspected the Speed Amplifier that no one knows what/how/why it's for. I have it wired as per the pictures in Techwiki
-red out of tacho conenected to black out of speed amplifier
-black out of speed amplifier to circuit board of dash
-green unused
I thought I'd try a few different combinations of these wires. DO NOT connect green and red without black. - smoke comes out of the speed amplifier!

Any suggestions as to my drama and how to fix appreciated

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The speedometer needs no electrical connection for working. If it works when spun by a drill, then the problem is the cable is not spinning.

The speed amplifier can be removed and discarded. All it does it trigger an emissions control.

i had the same problem just sourced a new speedo and problem was solved, it is possible to fix it as my old one now works after some fiddling.

My speedo sits below zero too. I have yet to drive it and test it but it moves the needle fine when spun. I was told anytime the speedo is sitting below zero like that it means the unit is broken. However i don't believe it to be the case. Djk what did you do to fix it?

Broken? In the sense that it is not normal, but doesn't mean it will fail to work. It can still read normal even if not sitting on zero




As I recall, the stock Datsun speedometer has a small wire that sticks out (nearly invisible) to stop the needle at zero. If the wire is bent or missing, it will go past zero but still work normally.