speedo not working

[y8sey]

my speedo has stopped working ,the mileage and mpg are ok. had it checked by bmw specialist they are saying a new dash pod is needed . has anybody got any other ideas?

[ian332isport]

my speedo has stopped working ,the mileage and mpg are ok. had it checked by bmw specialist they are saying a new dash pod is needed . has anybody got any other ideas?

If the mileage and mpg are both showing okay then it does sound like a problem with the speedo itself. If the speedo sender or wiring were faulty then you would loose both of these as well.

I once had a problem where my Speedo started to get intermittent. Sometimes it would work, other times it was totally dead. I also noticed that it seemed to come back to life when I had the heater on and the car was nice and toasty inside.

I traced the signal all the way from the diff sensor to the back of the instruments, and this proved to be working fine. I pulled the instruments and stripped them down, and had a good signal path all the way to the speedo head itself.

After thoroughly checking it over, I found what appeared to be a dry solder joint on the circuit board on the speedo head. After re-soldering the joint, everything worked fine. I also checked the same joint on another speedo, and it also showed signs of a bad joint.

If you look at the circuit board on the back of the speedo (talking about VDO here, not sure if Motometer is the same), you will see several components soldered to the board. One of these is a silicon chip of some sort. This is under the big coil of wire on the side of the speedo.

In the centre of the chip, are two very wide pins. The wide pin nearest to the edge of the circuit board is quite close to another component (capacitor) that is a small rectangular shape. If you look at the solder joint for this capacitor, you will hopefully see that it looks slightly cracked around the join. You may need a magnifying glass to see it clearly. Even if you can't see a faulty joint, it is always worth heating all the joints with a bit of fresh solder as dry joints are not always visible to the eye.

Mine has been fine ever since.

Cheers,

Ian.

[kevin316i]

Also check the connector on the back of the diff, the wires sometimes break here resulting in the loss of the speedo.

[ian332isport]

Also check the connector on the back of the diff, the wires sometimes break here resulting in the loss of the speedo.

If this was the case, he would also have lost the MPG swingometer and the odometer functions.

Ian.