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Test NTC-27A: Checking Radiator Fan Operation

NOTE: Perform TEST NTC-1A: NO TROUBLE CODES (NTC) TESTS  before proceeding.
  1. Using scan tool, actuate low speed radiator fan relay. Observe radiator fan. If radiator fan actuated, go to step  6. If radiator fan did not actuate, go to next step.
  2. Turn ignition off. Disconnect radiator fan motor connector. Turn ignition on. Using a 12-volt test light, check voltage on fused B+ circuit at low speed radiator fan relay connector. See LOW SPEED RADIATOR FAN RELAY CONNECTOR WIRE IDENTIFICATION  table. If test light is brightly illuminated, go to next step. If test light is not brightly illuminated, repair open fused B+ circuit. Perform TEST VER-2A: ROAD TEST VERIFICATION .
  3. Using a jumper wire, connect fused B+ circuit and low speed radiator fan relay output circuit at low speed radiator fan relay connector. See LOW SPEED RADIATOR FAN RELAY CONNECTOR WIRE IDENTIFICATION  table. Observe radiator fan. If radiator fan does not actuate, go to next step. If radiator fan actuated, replace low speed radiator fan relay. Perform TEST VER-2A: ROAD TEST VERIFICATION .
  4. Disconnect radiator fan motor connector. Using a 12-volt test light, check low speed radiator fan relay output circuit at radiator fan motor connector (harness side). See RADIATOR FAN MOTOR CONNECTOR WIRE IDENTIFICATION  table. If test light is brightly illuminated, go to next step. If test light is not brightly illuminated, repair open low speed radiator fan relay output circuit. Perform TEST VER-2A: ROAD TEST VERIFICATION .
  5. Using a DVOM, check resistance of both ground circuits between radiator fan motor connector (harness side) and ground. See RADIATOR FAN MOTOR CONNECTOR WIRE IDENTIFICATION  table. If resistance is less than 5 ohms on both ground circuits, replace radiator fan motor. Perform TEST VER-2A: ROAD TEST VERIFICATION . If resistance is 5 ohms or more on both ground circuits, repair open ground circuit. Perform TEST VER-2A: ROAD TEST VERIFICATION .
  6. Using scan tool, actuate high speed radiator fan relay. Observe radiator fan. If radiator fan actuated, radiator fan is operating properly. Test is complete. If radiator fan did not actuate, go to next step.
  7. Turn ignition off. Disconnect high speed radiator fan relay. Using a 12-volt test light, check voltage on fused B+ circuit at high speed radiator fan relay connector. See HIGH SPEED RADIATOR FAN RELAY CONNECTOR WIRE IDENTIFICATION  table. If test light is brightly illuminated, go to next step. If test light is not brightly illuminated, repair open fused B+ circuit. Perform TEST VER-2A: ROAD TEST VERIFICATION .
  8. Using a jumper wire, connect fused B+ circuit and high speed radiator fan relay output circuit at high speed radiator fan relay connector. See HIGH SPEED RADIATOR FAN RELAY CONNECTOR WIRE IDENTIFICATION  table. Observe radiator fan. If radiator fan does not actuate, go to next step. If radiator fan actuated, replace high speed radiator fan relay. Perform TEST VER-2A: ROAD TEST VERIFICATION .
  9. Disconnect radiator fan motor connector. Using a 12-volt test light, check high speed radiator fan relay output circuit at radiator fan motor connector (harness side). See RADIATOR FAN MOTOR CONNECTOR WIRE IDENTIFICATION  table. If test light is brightly illuminated, go to next step. If test light is not brightly illuminated, repair open high speed radiator fan relay output circuit. Perform TEST VER-2A: ROAD TEST VERIFICATION .
  10. Using a DVOM, check resistance of both ground circuits between radiator fan motor connector (harness side) and ground. See RADIATOR FAN MOTOR CONNECTOR WIRE IDENTIFICATION  table. If resistance is less than 5 ohms on both ground circuits, replace radiator fan motor. Perform TEST VER-2A: ROAD TEST VERIFICATION . If resistance is 5 ohms or more on both ground circuits, repair open ground circuit. Perform TEST VER-2A: ROAD TEST VERIFICATION .
LOW SPEED RADIATOR FAN RELAY CONNECTOR WIRE IDENTIFICATION

Application Wire Color
Terminal A
Fused Ignition Switch Output Circuit Light Green/Black
Terminal B
Fused B+ Circuit Red/Light Green
Terminal C
Low Speed Rad Fan Control Circuit Dark Blue/Pink
Terminal D
Low Speed Rad Fan Output Circuit Tan
RADIATOR FAN MOTOR CONNECTOR WIRE IDENTIFICATION

Application Wire Color
Low Speed Radiator Fan Relay Output Circuit Tan
High Speed Radiator Fan Relay Output Circuit Light Green
Ground Circuit (1) Black
(1) Both Black wires in connector are ground circuits.
HIGH SPEED RADIATOR FAN RELAY CONNECTOR WIRE IDENTIFICATION

Application Wire Color
Terminal A
Fused Ignition Switch Output Circuit Light Green/Black
Terminal B
Fused B+ Circuit Red/Brown
Terminal C
High Speed Rad Fan Control Circuit Dark Blue/Light Green
Terminal D
High Speed Rad Fan Output Circuit Yellow
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