89 240 DL - no speedo. No fuel or temp guage, no idiot lights
 

Here's a strange one. 89 240 DL.

The following has failed: speedometer, fuel guage, temperature guage and idiot lights. Checked everything. Cannot find problem.

Any ideas?

Have you had your instrument cluster out lately? There is a fuse on the back of the cluster that looks like a flexible plastic circuit board. If that blows, you will get symptoms like you describe.

I thought of that. And there is also a voltage regulator for 10 volts on the instrument cluster too.

If it is that fuse, where do get a replacement?

The alternator is only putting out 11 volts, which would cause insufficient voltage to the guage and lights.

11 volts off the alternator? obviously that won't help anything...have you tried revving the engine up to see if that will 'excite'
the alternator into working normally?

If the battery light is not functioning in your cluster then the alternator will not charge. This may be the cause of the low voltage reading.

You can easily check the fuse using an ohm meter. Just check the resistance between the two screws that attach the fuse to the cluster. Also, there is a u-shaped bare wire that runs from the speedometer circuit board to the main instrument cluster circuit board. This wire provides power to the main circuit board. Check to see that this wire is in place. Check all other connections in the cluster.

And whatever you do, don't connect the red/white wire to anything on the cluster unless you have a tachometer.