Glow Plug Test D Test Lamp Cycles Continuously

NOTE: Ford has updated it's Glow Plug Testing procedures please see TSB 88-11-19 in the TECHNICAL SERVICE BULLETIN Section.

Disconnect engine harness connector at control switch. Turn ignition on. Check voltage between control switch connector Pin No. 1 and ground. If voltage is 11 volts or more, turn ignition off and replace control switch. If not, turn ignition off and replace engine harness. Repeat GLOW PLUG SYSTEM TROUBLE SHOOTING and step 4 of GLOW PLUG TEST A .