LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Ford >> 1985 >> Cutaway 6.9 1 >> Repair and Diagnosis >> Engine Performance >> System >> Fuel Injection System - 6.9L Diesel >> Operation >> Glow Plug System
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Glow Plug System

Engine starting is aided by an automatic electric glow plug system. Function of this system is to pre-heat the combustion chamber to aid ignition of fuel.

System consists of eight glow plugs, control switch, power relay, "GLOW PLUG" lamp and a wiring harness which incorporates eight fusible wires (one for each glow plug) located between wiring harness and glow plug terminal.

Glow plugs are threaded into each cylinder combustion chamber. Glow plugs are small heaters that assist in cold starting. The glow plug controller and relay cycle 12 volts to these 6 volt heaters, which causes them to heat rapidly. After the engine starts, the glow plugs remain on between 4 and 10 seconds during initial starting cycle.