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Home >> Geo >> 1990 >> Tracker Base, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System/Component Tests >> Emission Systems & Sub-Systems >> Positive Temperature Coefficient (PTC) Heater >> System Check (A/T)

System Check (A/T)

  1. With engine coolant at approximately room temperature, turn ignition off and disconnect electrical connection at PTC heater, located between throttle body and intake manifold.
  2. Turn ignition on. Using test light connected to ground, backprobe Light Green/Red wire of PTC heater relay connector. Relay is the front relay located at right rear corner of engine compartment, in front of battery.
  3. If no voltage is present, check for open in Light Green/Red wire between relay and control relay. Control relay is located under left side of instrument panel near kick panel and fuse block.
  4. If voltage exists, use test light connected to ground and backprobe White/Black wire of electrical connector at PTC heater relay. If no voltage is present, check for open in White/Black wire between relay and main fuse box 30-amp fusible link. If voltage is present, proceed to step 5).
  5. Turn ignition off. Disconnect coolant temperature sensor located on right side of engine behind coolant hose. Turn ignition on. Using test light connected to ground, backprobe White/Green wire of electrical connector at PTC heater relay.
  6. If no voltage is present, check for open in White/Green wire between relay and ECM Yellow connector terminal No. 10 or faulty ECM. The ECM is located under left side of instrument panel near kick panel.
    NOTE: PTC relay and ECM control wire may be White/Blue on some models. To assist in terminal and wire identification, see appropriate wiring diagram in WIRING DIAGRAMS.
  7. If voltage was present, use test light connected to ground and backprobe PTC heater White/Blue wire of electrical connector at PTC heater relay. If no voltage was present, replace relay. If voltage was present, check for defective connections at relay or defective PTC heater assembly.
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