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ESC Performance Check

NOTE: Perform these checks only after checking ignition timing, MAP, EGR operation or if engine overheats.
  1. Connect tachometer to engine. Place shift lever in "P" (auto. trans.) or NEUTRAL (man. trans.). Run engine at fast idle (about 1500 RPM). With engine at normal operating temperature, tap engine block in area of detonation sensor. If RPM drops, system is operating properly.
  2. If RPM did not drop, disconnect ESC controller (located in engine compartment) and check for RPM change. If no change in RPM, proceed to step 5). If RPM drops, run engine at 2000 RPM. Unplug controller harness. Connect a digital voltmeter between ESC harness connector terminals "E" and "D". Voltage should not exceed 0.08 volts on the AC scale.
  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. 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 to "ON" position (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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