Hi,
"I have a clicking sound like a relay opening and closing quickly behind the left seat. It sounds like some is tapping Morse code."
"Just randomly stared one day and it happens at idle or while moving always when motor it operating temp not am Start when Engine cold. Have inspected the main relay which was fine no cracks and replaced both 4p relays on the bulkhead just to be safe. The car starts and drives fine but its an annoying sound. There are no codes and no other symptoms just clicking at various RPMs and drive states but nothing else correlates.
I suspect that the relay or wires, connector is not the cause of the problem.
That is definitely strange behavior. That relay should not be operating at low engine outputs. If you confirmed that you don't have some sort of intermittent ground on the red wire between the fuel pump relay and the ECU, then the ECU must be applying errant grounds causing the relay to operate (the ECU connects the red wire to ground to operate the relay). The ECU uses an internal transistor to switch the relay on and off; but when transistors fail they usually stay failed and most commonly as an open circuit. It might be possible that the ECU is getting some erroneous input signals causing the relay to engage and disengage.
There were 3 cases described on Prime.
I'm surprised by the solution:
1. Replacing the alternator
2. Repairing the engine-chassie ground (alternator replacing did not help)
3.Replacing ignition switch (this case probably concerned the Main Relay)
There is a verification procedure written in ETM. He suggests replacing my ECU with a functional one - confirmed from another car. I talked to R1 Motion, our friend from the forum. He has 37820-PBY-N01 Japan spec - mine is 37820-PBY-A01 US spec. It is not a cheap part (and there is no exact match) and the way the fault was solved on Prime means that I did not solve the problem. The common feature in solving the problem was power supply. (Alternator, ground). I noticed that these posts (errors) are from recent years. Our cars are getting old and knowing how to solve the problem can help others in the future. I encourage you to take action... I serve as an example.