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Low Coolant Indicator Inoperative (Commercial)

  1. Turn ignition switch to RUN position. Disconnect coolant level sender harness connector. Connect a fused jumper wire between Yellow/Black wire terminal at coolant level sender connector and ground. If low coolant indicator lights, go to step 4). If low coolant indicator does not light, go to next step.
  2. Disconnect instrument cluster harness connector. Connect a test light between harness connector terminal No. 32 (Pink wire) and ground. If test light lights, go to next step. If test light does not light, repair open in Pink wire.
  3. Using a fused jumper wire, backprobe instrument cluster connector terminal No. 4 (Yellow/Black wire) to ground. If low coolant indicator does not light, check bulb. If bulb is okay, replace instrument cluster. If low coolant indicator lights, repair open in Yellow/Black wire.
  4. Connect self-powered test light from coolant level switch harness connector Black wire terminal and ground. If test light lights, replace coolant level sender. If test light does not light, repair open in Black wire.


  1. Turn ignition switch to RUN position. Remove coolant level sender, but leave harness connector connected. Using test light, backprobe Black wire terminal at harness connector to battery power. If test light lights, go to next step. If test light does not light, repair open in Black wire.
  2. Using test light, backprobe Dark Green wire terminal at harness connector to battery power. If test light lights, go to next step. If test light does not light, replace coolant level sender.
  3. Using test light, backprobe instrument cluster harness connector terminal No. 4 (Yellow/Black wire) to battery power. If test light lights, go to next step. If test light does not light, repair open in Yellow/Black wire.
  4. Using test light, backprobe instrument cluster harness connector terminal No. 32 (Pink wire) to ground. If test light lights, repair and/or replace instrument cluster. If test light does not light, repair open in Pink wire.
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