Troubleshooting Speedo?
 

I have an 87 911, with the white faced electronic 220mph speedometer.
The speedo stopped working. I disassembled it, found disintegrated odometer gears, and replaced them (c/o OdometerGears, in Newport News, VA). I could rotate the odometer and it worked well.

However, upon reinstalling, the speedo still does not work.

I was told by various members to send it in to various speedo repair places, HOWEVER, they all want over $200 just to play with the unit. I'm thinking that it is possible that the sending unit outside the housing is bad and therefore the $200+ service would be a waste. Or maybe it's the electronic "vienna sausage" piece inside the speedo housing that needs replacement -- certainly not a $200+ expense.

Is there any way for a DIYer to check the electronic features to troubleshoot the speedo?

NOTE: I can buy a GPS speedo, which is far more accurate, and which is exactly matched to the original VDO lettering and numbering styles, etc., for less than $300 -- so I'm just not too keen on sending this old one off for a several hundred dollar checkup.
Would like to know if there is an easy DIY test of the more simple components that I might be able to repair.

Thanks.

Send your speedometer to Specialty Gauge in Manassas Va.!!! See my thread in the 964/993 section.
http://forums.pelicanparts.com/porsche-964-993-technical-forum/775738-993-speemometer-repair.html

Yel,
I'll give Cory a call. I had already called several other places recommended by Pelicaners, and they all told me it would be at least $250 (!), hence my reluctance to send it anywhere for a basic $250 charge.

where you can find the gps speedo that matches the original one?

Try calling this place Home they charged $120 to replace my 2 odometer gears
might be worth giving them a call

There is this thread

Speedometer thread

Raven,
Here is an example: . Auto From Speedhut.

You can play with different combinations of face, mpg/kph symbols, day and night lighting. According to their website, they will also do printing on the face to your specifications. Furthermore, you can also send a jpg picture of your instrument face with a ruler (or other relative object), and they will copy your logo (e.g. "Porsche" or "VDO"), other printing that normally appears on your stock gauge face, number sizes/font/script, etc.

The possibilities seem endless. The website is very interactive and, think of it -- GPS gauge for $251 or so. GPS is the future, and the future is now, in everyone's cell phones -- and the loss of not seeing your mph when driving in reverse is ridiculous, and the POSSIBLE loss of signal when driving thru a tunnel is of no consequence to me. That, and the fact that your speedo will never need to be recalibrated again, for less than the cost of repairing the old one, really has me struggling to think of the cons.

I do not know of the reliability of the GPS speedos, however.

I have not tried this company out, AND I have no affiliation with this company (Disclaimer). However, where there is one company, there certainly are others. Maybe you can do your own internet research and give us a few more possibilities.

I hear that boaters are using GPS speedos universally now.

Rick,
thanks for the link. I've got the speedo out and apart, so I'll check if any components are visually burnt.

Any suggestions on how to check the overall circuit board for functionality??
thanks.