Speedometer troubleshooting

[houseguy4]

First Porsche. Love it! 85.5 944
First post. Help!

Speedometer does not usually work - sometimes it will pop on for a few seconds and seem accurate, then stop working just as suddenly. This is VERY rare.
Odometer does not move either.
Seller said that when his toddler daughter sat in the rear seat, the speedo sometimes worked.

Had a general mechanic look at it, but I don't think he wanted to mess with it.

Before tearing open the dash, how can I troubleshoot the sending unit, the wire, the guage, and anything else?
Any suggestions are appreciated!

[ddbach]

Welcome, Congratulations

Odometer gears are known to have problems. Don't push the trip odometer reset while moving or your odometer is likely to have problems.

Porsche4Life has a great write up w/ pics here Dismantling a Gauge cluster

Others will have more on the speedometer

[Paulyy]

Congrats on your porsche 944.

try giving it a tap above it on the dashboard and see if it starts working, if that works then you have a loose wire. if not your speed sensor might be dirty try cleaning that.

with the odometer. mostlikley your gear is broken in it. like what ddbach states above

[Born2bwild1191]

Welcome! As ddbach said, odometer gears are usually destroyed. It's not too difficult of a job and you can get a gear for it online for 30 bucks. My speedometer would "pop" like that sometimes too, the guys on here told me to take it apart and lube up the cable that plugs into the back of the speedo. If i remember correctly i put a small amount of grease and sprayed a little WD40 in it. I haven't had a problem with it since. Good luck!

[houseguy4]

Thanks for the advice gang! Will give it a try.
I HATE cruising BEHIND people to avoid tickets!