Fuel pump relay switches on/off constantly

[Kalergie83]

Hi there.

My mechanic seems to have a problem with the switched ground of AUX6, which he assumes is the fuel pump relay.

When ignition is on, the fuel pump relay appears to switch on and off at a very high frequency (feels like 100hz). As soon as the engine runs, the relay stays on. It also stays on if he applies ground. 

Thank you for your help.

[Adamw]

This would suggest the relay coil has power from the ignition switch but the main ecu power supply is missing.  The ECU will still power up, but it will only be powered by current backfeeding through the aux outputs from other devices that have power.