Speedometer not working

[Donnyvan]

So i've been looking around on here for quite some time and just can't find the answers. After a sudden cold spell, I went out to my 91 300zx 2+2 na to find the speedo needle pinned at 0. The tach, odometer, and cruise all work fine. I went to a salvage yard and managed to find the exact same cluster I had in my car. Popped it in and same problem as before. Opened up the cluster and all the solder points looked fine and I went as far to check if the stepper motor in the speedometer worked and it does on both my old one and new one. I'm still new to cars but really want to fix this myself. Any help would be greatly appreciated.

[rgregoryb]

I did the same thing, it ended up being the "salvage" speedometer was bad also. If your cruise and odometer work it has to be a bad speedometer.

[DCaff300ZX]

Hmmmm, odd. Seems like you've done your homework and went the right direction so you'll need to look elsewhere probably.
Given the scenario of cold and sudden problem, plus your tests that indicate the two units both test good and look the same, I'd have to consider that the cold caused a odd short or broken wire somewhere that gets very cold- such as under the hood near the fuse box, or even the interior footwell as I've knocked off an odd thing or two getting into our tight little lady wearing boots, or cold weather gear that are bulkier than normal.
Try a careful inspection and continuity tests using the fsm for tests in that area, best possible solution other than an electrical repairman who truly will do just the same, but has more experience and the time due to your money.