I am a new member to this forum so please forgive me if I do something wrong.
I have a 1986 BMW 528e and I have been dealing with an intermittent starting problems like many others for years. Finally the car will not start at all so it gave me a chance to really do some testing.

First of all the car always cranks.
There is no spark.
After hours of reading many threads and performing numerous tests including the spark plugs, coil, cps, cpu, fuel and Main relays and also replacing most of those parts (except for the cpu) over a few years I believe I have found the problem.

There is not enough power coming from the Ignition to the Main relay pin 86.
There is not enough volts coming into pin 86 on the main relay to send enough power to pin 30 to close the bridge that supplies power to the two pin 87s. One of the Pin 87s provides power to the ECU, so the ECU is not receiving power when the ignition is turned on.

I have 12 volts coming into pin 30 before and after turning the ignition to the on position. However pin 86 is only receiving 4 volts when the ignition is in the on position and that is not enough power to close pin 30 bridge that supplies power to my two 87 pins when closed.

To test my theory I jumped pin 30 to both 87 pins and the car did start.
I also hooked up test leads from the relay harness slots and connected them to the pins on the bottom of the relay and when I did this and turned the ignition to the on position pin 86 could not provide enough power to close the bridge between pin 30 to both pins 87 as expected.

However when I disconnect the test lead from slot 86 on the harness (power supply coming from ignition to harness) and connect one end of the test lead directly to the battery and the other end to the bottom of pin 86 on the main relay, then turn on the ignition, pin 30 bridge now closes and provides power to both 87 pins and the car starts.

So being new to all of this and basically being an inexperienced Youtube mechanic, I believe I need to find a different power source for pin 86 on my Main relay that is currently being supplied from the ignition.

I know I can’t connect pin 86 straight to the battery because it would be sending power to ECU 24/7 and I believe running down the battery pretty quick.

Any suggestions as to a good alternative power source for powering pin 86 from the start position? I really want to bypass dealing with the ignition unless I really have to.

Any help would be appreciated and I apologize for making this so wordy.