The Power Electronics Module (PEM) in the Roadster is cooled by a DC Spal Fan which resides under the rear trunk tub, and fed by 12 volts from the PEM through a plug/socket connection.
Automotive grade connectors are used, not meant to be repeatedly disconnected during annual Preventive Maintenance, or PEM repairs.
Three things play into failures in this vital connection:
- The connectors are marginal or undersized based on current draw
- Pin regression occurs at the 90° bend over time on the PEM plug as the connection is plugged and unplugged
- Female pins on the fan cable socket get splayed with use, opening the connection making it harder to transfer sufficient current to the fan
The common failure mode is burned pins, and an inoperational PEM cooling function, initially throwing PEM cooling errors, and eventually shutting down the car.
We replace both connectors, and modify the PEM printed circuit board mount plug to eliminate pin regression. We also recommend replacement of this plug/socket combination, along with the PEM Cooling Fan, every 5 years.