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ESC Performance Check

NOTE: Perform these checks only after checking other causes of engine detonation, such as ignition timing, MAP, lack of EGR, or engine overheating.
  1. Connect tachometer to engine and run at fast idle speed (about 1500 RPM). Place shift lever in "P" (auto. trans.) or Neutral (man. trans.). With engine at normal operating temperature, tap engine block in area of detonation sensor. If engine RPM drops, system is operating properly.
  2. If RPM did not drop, disconnect ESC controller and check for RPM change. If no change in RPM, proceed to step 5. If RPM drops, run engine at 2000 RPM. Connect a digital voltmeter between ESC harness connector terminals "E" and "D". On the A.C. scale, reading should not be higher than .08 volts.
  3. If voltage reading is correct, problem is a faulty ESC connection or ESC controller. If voltage is not correct, check for an open in wire from ESC controller connector terminal "D" to ground.
  4. Repair if an open is found. If no open is found, check for an open or a poor connection between detonation sensor and ESC controller connector terminal "E". If circuit is okay, replace the detonation sensor.
  5. If no change in RPM in step 2, inspect "CHECK ENGINE" light. If light is on, problem is most likely a faulty ESC controller or detonation sensor. If light is off, turn ignition switch "ON" (engine not running) and check voltage from ground to ESC terminal "C".
  6. If voltage is under 2 volts, replace ECM. If voltage is over 2 volts, repair short in wire from ESC terminal "C" to ECM terminal "L".
NOTE: A knock sensor-to-controller wire that is routed too close to spark plug wires may cause retarded timing due to a false signal.
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