My '88 740 won't start. Turning the ingnition on only gets a single click response, like a bad starter. The dash board ingnition lights illuminate and the trouble happened all of a sudden. Following is what repair checks I have done so far:
1. Checked and charged battery, it is only a year and half old; tried jumping the battery with another vehicle to double check battery, too
2. Cleaned battery terminal posts
3. Replaced corroded positive battery cable connector at battery, this cable was replaced 4 years ago and a recall replacement was done in '96, too
4. checked, cleaned & reseated battery cable grounds to chasis and engine block
5. replaced starter after having it checked under load condition
6. swapped out many circuit board relays with used spares, replacing originals after no response

In the past 5 years some other electrical repairs were made: the distributor plate was replaced, fuel pump relay switch was replaced, replaced turn signal/emerg. flasher steering column switch and had a couple electrical grounds were repaired. Spark plugs replaced in November. But, the distributor cap, rotor and wires have not been replaced since late '99 with 38,000 miles put on car since that time.