So today I thought I'd do the large tach / small clock upgrade. Now mostly everything on the cluster is dead!

What is working:

High Beam indicator
turn signal lamps
small clock

Whis isn't working:

Everything else! (tack, odo, speedo, idiot lights, gas/temp)

Since the small clock is working I know that there is 12V getting to tach and hence the cluster.

Anyone know why everything else is dead? This is killing me. And yes, I am sure everything is hooked up correctly and have pulled the dash a few times before.

Greetings Fiver,

Yes you have +12 battery for the clock. Gauge lighting also arrives separately, so you have some backlighting perhaps.

But the switched +12 (and ground) arrives via the three pin connector at the speedo's circuit board -- the nylon edge connector that slides off so easily.

That voltage is not fused, yet the cluster wiring itself is protected by a film circuit link between two of the speedo screws. The place to start would be the nylon connector at the back of the speedo.

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Art Benstein near Baltimore

Thanks Art!! I inspected the little ribbon guy, it looked good and had continuity at both ends. Then I looked at the speedo connector, the contacts seemed a little loose so I tightened up each one by pushing in with a tiny screwdriver. Plugged it back in and like magic everything worked!

You're welcome, Fiver.

Save that technique for your tail lights too. Same connector.
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Art Benstein near Baltimore