How to Check a Porsche 944-911 DME Relay
The Porsche 944-911 DME relay contains 2 relays inside its housing.
The 1st relay provides power to the DME. In the 944 Turbo, the primary relay powers the KLR ignition unit.
The 2nd relay provides power to the fuel pump.
Most "non-starting" symptoms can be attributed to a defective DME Relay. This might be caused by broken solder joint inside the relay. This is why if you let the car sit for awhile, after the car (really, the relay) cools down, the car will restart.
One option that you have, if you do not want to buy another DME Relay, is to re-flow ALL the solder points on the board of the relay.
This solution might cure an intermittent starting issue with your Porsche 944 or 911.