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Glow Plug Test E Test Lamp Does Not Cycle

NOTE: Ford has updated it's Glow Plug Testing procedures please see TSB 88-11-19 in the TECHNICAL SERVICE BULLETIN Section.
  1. Connect a test lamp between glow plug power relay output and ground. Turn ignition on, but do not start engine. If test lamp lights, proceed to step 2. If test lamp does not light, for coolant temperatures of 140° F (60° C) or above, condition is normal. For coolant temperatures below 140° F (60°C), turn ignition off, wait 5 minutes, and turn ignition back on. If lamp lights, proceed to step 2. If lamp does not light, perform GLOW PLUG TEST C.
  2. Turn ignition off. Disconnect chassis harness from glow plug power relay. Disconnect engine harness from control switch and all glow plugs. Check resistance between control switch connector Pin 4 and glow plug relay power output. If resistance is less than 1 ohm, go to step 4. If resistance is 1 ohm or more, proceed to step 3.
  3. Turn ignition off. Disconnect chassis harness from engine harness. Check resistance between chassis harness and glow plug power relay output. If resistance is less than 1 ohm, replace engine harness. If more than 1 ohm, replace fusible link(s) or repair chassis harness. Repeat GLOW PLUG SYSTEM TROUBLE SHOOTING  .
  4. With ignition off, check resistance between control switch connector Pin 5 and ground. If resistance is less than 1 ohm, proceed to step 5. If not, repair engine harness ground connection or replace harness. Repeat GLOW PLUG SYSTEM TROUBLE SHOOTING  .
  5. With ignition off, disconnect engine harness at control switch. Connect all other leads. Check resistance between control switch Pin 6 and ground. If resistance is 2.5 ohms or more, replace control switch. If not, replace power relay. Repeat GLOW PLUG SYSTEM TROUBLE SHOOTING  and step 4 of GLOW PLUG TEST A  .
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