DTC P1676: Fuel Injectors Open Or Short Circuit

Inspect fuse No. 16B in dashboard fuse block and replace if necessary. See Figure. Connect TECH 2 scan tool to Data Link Connector (DLC). Turn ignition on. Select ACTIVATE: FUEL INJECTORS. Operate each injector one at a time and listen for a ticking sound from each injector. If only one injector can not be heard, go to next step. If no injectors can be heard at all, check for faulty circuit between fuse No. 16B and spliced crimp connection J34 located in engine wiring harness (Green/Red wire). See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. For DTC P0300 and P1300, go to step 4. For DTC P0340, go to step 3 of DTC P0340 diagnostic procedure. Otherwise, go to step 7.
Disconnect harness connector from suspect fuel injector. Connect SST 86 11 857 test light (see Figure) or equivalent between fuel injector harness connector terminal No. 1 (Green/Red wire) and ground. See Figure. If test light illuminates, go to next step. If test light does not illuminate, check for faulty circuit between suspect fuel injector harness connector terminal No. 1 and spliced crimp connection J34. Repair as necessary. For DTC P0300 and P1300, go to step 4. For DTC P0340, go to step 3 of DTC P0340 diagnostic procedure. Otherwise, go to step 7.
Connect both test light leads to fuel injector harness connector terminals No. 1 and 2. Use scan tool to select ACTIVATE: FUEL INJECTOR. If test light does not illuminate, repair faulty circuit between pertinent fuel injector harness connector terminal No. 2 and following ECM harness connector terminal:
- Cylinder No. 1: terminal No. 45 (Green/Black wire).
- Cylinder No. 2: terminal No. 44 (Green/White wire).
- Cylinder No. 3: terminal No. 67 (Purple/White wire).
- Cylinder No. 4: terminal No. 68 (Grey/White wire).
See Figure for ECM location. See Figure. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light does illuminate, replace faulty fuel injector. See FUEL INJECTORS under FUEL SYSTEM in REMOVAL, OVERHAUL & INSTALLATION article. Repair as necessary. For DTC P0300 and P1300, go to next step. For DTC P0340, go to step 3 of DTC P0340 diagnostic procedure. Otherwise, go to step 7.
Use scan tool to select ACTIVATE: RESET MISFIRE AND KNOCK COUNTERS. Test drive vehicle and monitor current readings for MISFIRE CYL 1-4. During test drive, duplicate previously noted freeze frame values for ENGINE SPEED, AIR MASS/COMBUSTION and COOLANT TEMPERATURE. If any misfire/knock counters are incrementing continuously, problem is still present. If no counters are incrementing continuously, for DTC P1300, go to next step. Otherwise, clear DTCs.
NOTE: A few misfires are acceptable as long as counter is not incrementing at a continuous rate.
Use scan tool to check if DTC P0420 has been stored. If DTC P0420 is present, go to next step. If DTC P0420 is not present, test drive vehicle at varying speeds for 5 minutes under the following conditions: do not allow engine to idle for more than 40 seconds, and do not allow engine to brake vehicle with released brake pedal for more than 10 seconds. Afterwards, test drive vehicle on level ground for 1 minute between 43-56 MPH. Check scan tool display for diagnostic status of DTCs. If scan tool display reads OK, clear all system DTCs. If scan tool reads NOT READY, back up to INITIATING DIAGNOSTICS and recheck DTC status. If scan tool displays DTC P1300, go to next step.
Replace catalytic converter and use scan tool to clear all system DTCs.
Use scan tool to clear all system DTCs. Drive vehicle for 5 minutes under varying loads and engine RPM. Recheck for any stored DTCs. If P1676 is present, substitute known good ECM and retest system. See ENGINE CONTROL MODULE (ECM) under COMPUTERIZED ENGINE CONTROLS in REMOVAL, OVERHAUL & INSTALLATION article.