Scan Tool Does Not Communicate With Class 2 Data Line

Remove the scan tool from the Data Link Connector (DLC). Disconnect the Powertrain Control Module (PCM). Test for an open or short to ground in the power circuit(s) to the PCM. See PCM POWER & GROUND CHECK in SYSTEM COMPONENT TESTING - 2.2L article or PCM POWER & GROUND CHECK in SYSTEM COMPONENT TESTING - 2.4L article in ENGINE PERFORMANCE. If there is no fault in the power or ground circuits, go to next step. If there is any fault, repair and perform data link communications system check. See DATA LINK COMMUNICATIONS SYSTEM CHECK .
Test for an open in the ground circuit(s) to the PCM. See PCM POWER & GROUND CHECK in SYSTEM COMPONENT TESTING - 2.2L article or PCM POWER & GROUND CHECK in SYSTEM COMPONENT TESTING - 2.4L article in ENGINE PERFORMANCE. If there is no fault in the power or ground circuits, go to next step. If there is any fault, repair and perform data link communications system check. See DATA LINK COMMUNICATIONS SYSTEM CHECK .
Test for an open, short to ground or short to battery between terminal No. 2 of the DLC and connector C1 terminal No. 59 of the PCM with a DVOM. See Figure . If there is no fault in the circuit, go to next step. If there is any fault, repair and perform data link communications system check. See DATA LINK COMMUNICATIONS SYSTEM CHECK .
Replace the PCM. See POWERTRAIN CONTROL MODULE (PCM) under COMPUTERIZED ENGINE CONTROLS in REMOVAL, OVERHAUL & INSTALLATION - 2.2L article or POWERTRAIN CONTROL MODULE (PCM) under COMPUTERIZED ENGINE CONTROLS in REMOVAL, OVERHAUL & INSTALLATION - 2.4L article in ENGINE PERFORMANCE. Perform data link communications system check. See DATA LINK COMMUNICATIONS SYSTEM CHECK .