Brake Controller Harness for '87-91 Trucks
The rubber grommet near the red sticker passes thru the firewall near the e-brake pedal. A second pigtail harness plugs into the round 3-pin connector and splices to the controller's wiring.
http://www.revbase.com/BBBMotor/Wd/DownloadPdf?id=57184'80-86 similar
