[SilveronBlu]

My tach seems to be receiving power, because it illuminates in the same way as the spedo when the lights are on, but the needle doesn't work; it just sits there at the bottom of the range. Im curious if anyone has experienced this and/or knows of any common reasons/solutions for this unfortunate problem.

Thanks

Sam

 

[ghnl]

Is the engine running?

That the lights come on just means the lighting circuit is good. That says nothing about the tach circuitry.

Also, it helps to remind us what model year (and color...) Spider we're dealing with. The earlier models have a mechanical tach, later models have an electronic tach.

 

[SilveronBlu]

Sorry, I forgot to mention it's an 84 spider veloce non a/c version. 110k miles, no modifications. And yes, as the previous poster had inquired, the motor is running...

Sam

 

[ghnl]

OK, then your unknown color 1984 Spider would have an electronic tach in the dual pod dash. There should be a trigger wire off the coil for tach function. I believe it is a white wire. Check for its presence and continuity to the tach.

 

[phil c]

sometimes it could be as simple as a corroded fuse..

check the connections.

 

[Tifosi]

unknown color 1984 Spider

Based on a few scattered clues, I'd hazard it's silver w/blue interior, but I could be well off on that

The backlight is a totally seperate circut from the one that makes the needle move.
You can have lights and no tach as easily as you can have tach and no lights.

However, since you do have lights, it suggests that at least the ground wire is connected properly. Have a looksee at the coil -ive terminal to see if there's a standard gauge white wire affixed to it. That would be the signal wire that goes to the tach. (there's a slightly heavier gauge white wire there too, but it deals with the ignition control unit, not the tach)