Yes, the Tekonsha Plug-In Wiring Adapter, # 3035-P, can be purchased separately from the Tekonsha Primus IQ Brake Controller, # Tk90160.
The OEM harness on your 2009 Lincoln Navigator will be located up under the dash near the center console. There will be a 6-pin connector that mates with the one on the adapter at the end of the harness. view full answer...