My 1989 760 turbo waogn will not start. I checked for spark by grounding a plug and nothing happened. No spark from the coil either, but power is going to both side of the coil. Any help would be appreciated

Yes you should have 12 volt power at both terminals of the coil. In at the + and out to ground Via circuit breaker device from the - to complete the circuit,"Check this wire is not broken or disconnected".the coil terminals are the ends of the primary coil winding that surrounds and energizes the core. The HIGH VOLTAGE spark to the plugs is induced electicity captured by the secondary winding passed on to distributor by the high tension cable and then jumping the plug gap to grounnd.The low voltage 12 volt circuit has to be broken by a circuit breaker "See my previous posting" to collapse the magnenetic field for the spark to occur. It would seem that this is not happenning with your ignition control system,given you are saying that your coil works fine on bench test.
Regards Bill N.Z

Simiplistic, but have you checked the coil wire itself to the distributor?

Hi--did you check and make see that the timing belt isnt broke or not turning--take the oil cap off and have someone crank the motor over while you watch to see the camshaft spinning. If not--timing belt broke or the crankshaft timing belt gear has sheared its keyway--sounds weird--but happened to me a few days after the harmonic balance gave me warning that it was ready to go--everything loosened up and caused the key to shear off. Not a hard repair-did a new timing belt and front seals while doing the harmonic balancer and gear--ok now. Good luck

Might want to replace the coil.

I tested the coil at an auto parts store and it checked out fine. Any other ideas??

When current flows through the low voltage "12 volt" primary windings of the coil it causes the core to become an electic magnet creating a magnetic field. The magnetic field collapses when the circuit is broken,as by circuit breaker points in the distibutor in older ignition systems, and whatever device is used to break the circuit in the electronic system,"Possibly RPM/Crank angle, or Hall sensor! High voltage electricity is then induced into the secondary winding and is passed onto distributor Via high tension wire from centre of the coil.
If your coil is bench testing OK off the car,then it would seem that the cicuit breaker, whatever that may be on your car is not working. There is a ignition power amplifier gizmo that could possibly be involved bolts to the front left inside wheel arch on my 760 GLE V6, just back from washer bottle. May be in the same place on yours. Good gremlin hunting.
Regards Bill N.Z.

Thanks for the hints. I checked the timing belt by turning over the engine and watching the cam - seems to work. Took another look at the coil and with the ignition in the run position, there is power (12 v) to both sides of the coil. Is this normal??