So, after replacing all the capacitors, running a jumper wire from a burnt part of the circuit, and resoldering all the joints on the printed circuit board on the cluster of my 1992 volvo 740 wagon, the speedometer still isn't working. It will jump up to 65MPH when I start the car, and then go back to zero. It initially just remained at 0.

I'm wondering if that would be a sign of the sensor on the rear differential messing up? I haven't gotten into that yet.

Second, I came across this on ebay:

Autometer 1796 Old Tyme Black Series Speedometer 0 120 MPH 3 1 8" Dia Mechanical | eBay

It claims the unit is compatible with my make and year, but I'm wondering if anyone has any experience with this brand and if you have to do anything special to install it?

 

The speedo repair is tricky, hit and miss affair--unfortunately sometimes is just doesn't pan out. The dif sensor is rarely at fault.

I don't see how this e bay speedo would work barring major mods. This is cable driven, the '92 Volvo is electric, where do you put the cable? Which cable? It won't fit in the pod, etc. A speedo is a speedo and anything may be adopted but definitely not "plug and play"!

 

Ah, yeah. That's what I was thinking. It didn't really look like the speedo would fit from the picture, and I didn't look at any of the specs.

However, I did look at the speedo sensor on the rear axle. The two wires were completely ripped off. I tried the trick where you turn the vehicle on and tap the two wires together to see if the speedo works. I got nothing.

So, I just intend to get some GPS speedometer that plugs into the cigarette lighter.

If it's not one thing, it's another!

 

Have you considered getting a replacement cluster? and more importantly fixing that sensor?

 

GPS speed is only accurate when traveling in a relatively straight line, and it lags speed changes by 100 feet or more. it also has real problems in heavily urbanized areas when you're surrounded by tall buildings, or in heavy forests with dense tall trees.