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Glow Plug Test C Test Lamp Does Not Light

NOTE: Ford has updated it's Glow Plug Testing procedures please see TSB 88-11-19 in the TECHNICAL SERVICE BULLETIN Section.
  1. Ensure that ignition has been off for at least 1 minute, then turn ignition on. If "GLOW PLUG" dash light comes on, perform GLOW PLUG TEST E  . If not, for engine at normal operating temperature, condition is normal. For coolant temperatures below normal, turn ignition off, wait 2 minutes, and turn ignition back on. If light comes on, perform GLOW PLUG TEST E  . If light does not come on, proceed to step 2.
  2. Check batteries for sufficient charge. Batteries should be able to crank engine. If charge is ok, proceed to step 3. If charge is low, charge or replace batteries as necessary and repeat GLOW PLUG SYSTEM TROUBLE SHOOTING  .
  3. Turn ignition off. Wait at least 1 minute, then connect test lamp between power relay output and ground. Turn ignition on. If test lamp comes on but dash light does not, repeat GLOW PLUG LAMP TROUBLE SHOOTING  , step 3. If test lamp does not light, proceed to step 4.
  4. Check fusible link from ignition switch to control switch. If fusible link is ok, go to step 8. If fusible link is not ok, proceed to step 5.
  5. Replace fusible link and repeat GLOW PLUG SYSTEM TROUBLE SHOOTING  . If fuse blows, proceed to step 6. If fuse does not blow and system operates correctly, testing is complete. If fuse does not blow and system still does not operate correctly, go to step 8.
  6. Remove signal lead from power relay. Replace fusible link. Turn ignition on and then off. If fuse blows, proceed to step 7. If fuse does not blow, replace power relay and repeat GLOW PLUG SYSTEM TROUBLE SHOOTING  .
  7. Disconnect chassis harness from engine harness. Replace fusible link. Turn ignition on and then off. If fuse blows, repair chassis wiring harness and repeat GLOW PLUG SYSTEM TROUBLE SHOOTING  . If fuse does not blow, proceed to step 8.
  8. Turn ignition off. Reconnect all leads (including power relay signal lead). Wait at least 1 minute and turn ignition back on. Check voltage between power relay signal lead and ground. If voltage is at least 11 volts, proceed to step 9. If less than 11 volts, go to step 10.
  9. With ignition off, check voltage between power relay input terminal and ground. If voltage is at least 11 volts, check power relay ground connection or replace relay. If voltage is below 11 volts, charge or replace batteries and/or repair wiring from batteries to power relay. Repeat GLOW PLUG SYSTEM TROUBLE SHOOTING  .
  10. With ignition off, disconnect power relay signal lead and engine harness at control switch. Check resistance between control switch connector Pin No. 6 and power relay signal lead. If resistance is less than 1 ohm, go to step 12. If not, proceed to step 11.
  11. With ignition off, disconnect chassis harness from engine harness. Disconnect power relay signal lead. Check resistance between chassis side wiring connector terminal No. 6 and power signal lead. If resistance is less than 1 ohm, replace engine harness. If not, repair or replace chassis wiring. Repeat GLOW PLUG SYSTEM TROUBLE SHOOTING  .
  12. Remove engine harness connector to control switch and turn ignition on. Check voltage between control switch connector Pin No. 3 and ground. If voltage is 11 volts or greater, replace glow plug control switch and repeat GLOW PLUG SYSTEM TROUBLE SHOOTING  . If voltage is less than 11 volts, proceed to step 13.
  13. Turn ignition off. Disconnect chassis harness from engine harness, Turn ignition back on. Check voltage at Pin No. 3 on chassis side of connector. If voltage is 11 volts or greater, replace engine harness. If not, repair or replace chassis wiring. Repeat GLOW PLUG SYSTEM TROUBLE SHOOTING  .
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