ESC Performance Check

NOTE: Perform these checks only after checking other causes of engine detonation, such as ignition timing, lack of EGR, or engine temperature.

Run engine at fast idle speed and place shift lever in "PARK" (auto, trans.) or "NEUTRAL" (man. trans.). Note timing change as exhaust manifold is tapped with a plastic hammer. If timing is retarded, system is operating properly.
If timing is not retarded, disconnect detonation sensor. Connect a jumper to detonation sensor connector terminal, forming jumper into a loop on top of distributor (or hold it along a spark plug wire). Note timing.
If timing is not retarded, reconnect detonation sensor. Disconnect ESC controller connector and attach ohmmeter leads to terminals "B" and "K" of connector. Resistance should be 175-375 ohms. If resistance is OK, replace ESC controller. If not OK, repair ESC harness.
If in step 2), timing was retarded when jumper loop was placed over distributor, connect ohmmeter leads to detonation sensor. Resistance should read 175-375 ohms. If not, replace sensor.
If resistance is correct, reconnect detonation sensor. Disconnect ESC controller connector. Touch ohmmeter leads to terminals "B" and "K" of connector. Resistance should again read 175-375 ohms. If OK, replace sensor. If not OK, check for an open in wires to terminals "B" and "K". If wires are OK, repair sensor connection. If wires are defective, replace or repair harness.