Speedometer not working....


phoenix

GT Owner
Nov 27, 2005
39
Cartersville, Georgia
The other day, when I drove to work in the GT, I noticed the speedometer did not register at all - it sat on zero, but the odometer marked off the 10th of a mile, as I drove. Then at lunch, the speedometer worked soon as I started to move. I did not drive the car again for about a week and the same thing happened - zero & the odometer worked, but later in the day on the way home it still did not work. Only thing is common was both of the days it was cold, but leaving the house - the car had spent the night in a warm carport........any ideas?
 

shelbyelite

PERMANENTLY BANNED
May 10, 2007
1
I had a GT one time that if you started the car WITH the door open, the speedo, etc would not work. if you started it with the door closed, everything worked as it should. Never really figured it out....
 

Kingman

GT Owner
Mark II Lifetime
Aug 11, 2006
4,072
Surf City, USA
I had a GT one time that if you started the car WITH the door open, the speedo, etc would not work. if you started it with the door closed, everything worked as it should. Never really figured it out....

I didn't realize the Brits had a hand in the electrical design!? :slap
 

Spirit

Heritage GT Owner
Mark IV Lifetime
Le Mans 2010 Supporter
I didn't realize the Brits had a hand in the electrical design!? :slap

:lol:lol:lol:lol:lol:lol
 

SFLGT

Well-known member
Dec 29, 2007
205
FtLauderdale,Florida
Phoenix, There are a couple of things that could be the problem. First thing to check is you batter voltage and charging voltage. The gauges are the first thing to react when Bart voltage drops in the GT. I have seen a lot of erratic gauge complaints cased by low batt. charge after cars have sat for awhile. It's very common. If the batt is fully charged and no shorted cell problems or anything like that you most likely just have a sticking speedo and the gauge needs to be replaced. You said that the odometer is working so the cluster control module is working and getting a speed signal. The gauge is a simple 3 wire setup with a 12v wire, speed signal input from the gauge control module and a signal return. Since the gauge does work sometimes there are no broken wires or damaged pins in a connector. I have seen on 2 cars the electrical harness that runs to the gauge control module over top of the steering shaft laying on the shaft and causing it to rub through and cause some problems, bu they we're not intermittent. Would hurt to just look up under your dash over the steering upper shaft and just check to be sure, but I would say you are looking at a speedo replacement.
 

NoTickets

New member
Jan 20, 2008
2
Battery

If it works on one start and not the next, it's the battery. I had the problem with the oil pressure, which is a more exciting problem to have. No that I use a battery charger, no problems. One time the speedo didn't work also.