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Home >> Jeep >> 1998 >> Wrangler Sahara, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes - Engine Performance >> Self-Diagnostic Tests >> Test NTC-29A: Checking Fuel Heater Relay
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Test NTC-29A: Checking Fuel Heater Relay

NOTE: This test applies to vehicles equipped with diesel engine only. For connector terminal identification, see CONNECTOR IDENTIFICATION . For component location and wiring diagram, see WIRING DIAGRAMS article.
NOTE: To hear click in next step, it may be necessary to remove and install relay several times.
  1. Turn ignition on. While listening for relay to click, remove fuel heater relay. If relay clicks, go to step 5)  . If relay does not click, go to next step.
  2. Inspect fuel heater relay connector and terminals for damage. Repair connector and terminals as necessary and perform TEST VER-2A: ROAD TEST VERIFICATION . If connector and terminals are okay, go to next step.
  3. Using an external voltmeter, check voltage on fuel heater relay connector, fused ignition switch output circuit (Light Green/Black wire). If voltage is 10 volts or less, repair open fused ignition switch output circuit and perform TEST VER-2A: ROAD TEST VERIFICATION . If voltage is more than 10 volts, go to next step.
  4. Turn ignition off. Using an external ohmmeter, check resistance of fuel heater relay connector, ground circuit (Black/Tan wire). If resistance is more than 5 ohms, repair open ground circuit and perform TEST VER-2A: ROAD TEST VERIFICATION . If resistance is 5 ohms or less, replace fuel heater relay an perform TEST VER-2A: ROAD TEST VERIFICATION .
  5. Turn ignition off. Disconnect fuel heater connector. Inspect connector and terminals for damage. Repair connector and terminals as necessary and perform TEST VER-2A: ROAD TEST VERIFICATION . If connector and terminals are okay, go to next step.
  6. Using an external ohmmeter, check resistance of fuel heater connector, ground circuit (Black/Tan wire). If resistance is 5 ohms or more, repair open ground circuit and perform TEST VER-2A: ROAD TEST VERIFICATION . If resistance is less than 5 ohms, go to next step.
  7. Turn ignition on. Using an external voltmeter, check voltage on fuel heater relay connector, fused B+ circuit (Red/Tan wire). If voltage is less than 10 volts, repair open fused B+ circuit and perform TEST VER-2A: ROAD TEST VERIFICATION . If voltage is less than 10 volts, go to next step.
  8. Turn ignition off. Using an external ohmmeter, check resistance of fuel heater relay output circuit (Red/Black wire) between fuel heater relay connector and fuel heater connector. If resistance is more than 5 ohms, repair open fuel heater relay output circuit and perform TEST VER-2A: ROAD TEST VERIFICATION . If resistance is 5 ohms or less, go to next step.
  9. Disconnect fuel heater element connector. Inspect connector and terminals for damage. Repair connector and terminals as necessary and perform TEST VER-2A: ROAD TEST VERIFICATION . If connector and terminals are okay, go to next step.
    NOTE: Ensure fuel heater element temperature is less than 40°F (4.4°C).
  10. Reconnect fuel heater element connector. Using an external ohmmeter, check resistance across fuel heater connector terminals (component side). If resistance is 5 ohms or less, fuel heater is operating properly. Test passed. If resistance is more than 5 ohms, replace fuel heater and perform TEST VER-2A: ROAD TEST VERIFICATION .
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