'86 740 GLE speedometer/tachometer

My odometer stopped working so I removed the cluster and took apart the
speedometer to get to the odometer. The problem with the odometer was what
I suspected,a plastic gear was stipped. I replaced it and put the cluster
back in the car. The car wouldn't start so I switched two wires on the
back of the speedometer and it started. Now the speedometer and tachometer
are not working. I'm thinking that I fried the speedometer sending unit.
Does anyone know if the tachometer would be affected by the speedometer
sending unit?

 

It's easy to put the tach wire on in the wrong place. If you do, then
you can ground the ignition signal, which results in no start. Sounds
like you still have the tach wire in the wrong place, just not as
wrong. The speedometer power, ground and signal are all connected in
the one 3 or 4 pin plug that connects on the bottom edge of the speedo,
so it's hard to connect in such a way as to kill the sender. However,
it's not the greatest system, so the connections can be poor.

--
Mike F.
Thornhill (near Toronto), Ont.

NOTE: new address!!
Replace tt with t (twice!) and remove parentheses to email me directly.
(But I check the newsgroup more often than this email address.)

 

I figured out what I did. I went to the junkyard and got another cluster,
there are 2 connections at the top of the speedometer. When I took the
cluster apart I put the 2 wire on the wrong side. I really screwed up. So
something is definately fried, just don't know what yet. It's obviously
whatever connects to the other end of those 2 wires, just don't know what
yet. Maybe the speedo sending unit. Any ideas?

 

I figured out what I did. I went to the junkyard and got another cluster,
there are 2 connections at the top of the speedometer. When I took the
cluster apart I put the 2 wire on the wrong side. I really screwed up. So
something is definately fried, just don't know what yet. It's obviously
whatever connects to the other end of those 2 wires, just don't know what
yet. Maybe the speedo sending unit. Any ideas?

 

I figured out what I did. I went to the junkyard and got another cluster,
there are 2 connections at the top of the speedometer. When I took the
cluster apart I put the 2 wire on the wrong side. I really screwed up. So
something is definately fried, just don't know what yet. It's obviously
whatever connects to the other end of those 2 wires, just don't know what
yet. Maybe the speedo sending unit. Any ideas?

 

Did you blow the fuse?

 

Checked all the fuses in the dash. When I hook up the wire on the back of
the speedo the car stalls, it won't even start when it's hooked up. I
disconnect the wire and it starts and runs fine.