Note On Intermittents
With engine running, manipulate oxygen sensor, ECM wiring, and connectors while observing ECM parameter ED33. If fault is induced, ED33 will jump to greater than .63 volt, and ECON status light will go on. Manipulate circuit No. 413 ground to engine, and look for a loose ground eyelet or ground eyelet installed at wrong location. If oxygen sensor circuit is okay or lean engine operation is suspected, perform DFI SYSTEM CHECK.