Georgia Tech’s EcoCAR team had a great Spring Workshop, but the runup to the event was no picnic. For weeks leading up to the EPA testing, team members lost sleep getting the car back to life after two major issues threatened to sideline the vehicle.
First, electrical group members moved the Engine Control Module (ECM) into the new location where it would have less vibration, less wire clutter and less abrasion on the wiring conduit. The work seemed innocuous initially, but when they plugged the connectors back into the ECM and powered up the 12V disconnect, a fused popped, causing the vehicle to lose internal network communications and accessory power.
The team suspected the cause of the issue was wiring, so they spent two weeks stripping the conduits off the wiring harness, inspecting every wire going into the ECM, checking continuity in every pinout of the ECM connectors and reviewing the specification to see if any feature in ECM which would trigger this. They also shipped the ECM to General Motors for an inspection, but GM mentors informed the team that the component had no issues.
At a regular electrical group meeting only a few weeks prior to the Spring Workshop, the group was inspecting the new connectors GM had shipped when team member Carlos Cubero-Ponce ran in holding his laptop. He pointed at the schematic picture and revealed to the team’s shock that there was a simple answer to their electrical issue. The J1 connector was plugged in the wrong direction! Behind the pile of engineering documentations, the team had taken for granted that the connectors cannot be plugged in upside down.
Just days after resolving the ECM issue, Georgia Tech encountered another problem when an input shaft snapped off their 2-Mode transmission during testing. This required the team to replace the entire transmission, but luckily one arrived from GM without a day to spare. The team was able to make the proper adjustments to their vehicle and ship it off to the Spring Workshop just in the nick of time!