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Check Engine Light On, Led Won't Flash Code (2.1L)

  1. Turn ignition on. If CHECK ENGINE light stays on after 2 seconds, go to step 2). If CHECK ENGINE light turns off, problem is intermittent. Test drive vehicle. Check for loose wires and connections at thermostat housing and main relay connector. Check ECU fuse at underhood fuse/relay block and fuse No. 12 at fuse/relay block, behind left side of dash.
  2. Check if LED is flashing code(s). If LED is flashing codes, repair trouble codes. If LED won't flash code(s), try starting engine. If engine does not start, go to next step. If engine starts, go to step 8).
  3. Remove and inspect ECU (10A) fuse in underhood fuse/relay block. Replace as necessary. If fuse is okay, inspect fuse No. 12 (10A) at fuse/relay block, behind left side of dash. Replace as necessary. If fuse is okay, go to next step.
  4. Turn ignition on. Individually disconnect 3-wire connector at MAP, TPS and EGR valve lift sensors while observing CHECK ENGINE light. If CHECK engine light goes off, replace sensor causing light to go off when disconnected. If CHECK ENGINE light stays on, go to next step.
  5. Turn ignition off. Connect ECU Test Harness (07999-PD6000A ). Disconnect ECU connector "D" from ECU, not main wire harness. Using an ohmmeter, check continuity between body ground and terminals D19 and D20. If continuity does not exist, go to step 6). If continuity exists, check short to ground in Red/White wire or Yellow/White wire between ECU terminals D19 and D20 and MAP, TPS and EGR valve lift sensors.
  6. Reconnect all connectors. Reconnect connector "D" to ECU. Turn ignition on. Using a voltmeter, measure voltage between ECU terminals A26 (-) and B1 (+) and between terminals A26 (-) and A25 (+).
  7. If battery voltage is present at these terminals, substitute a known good ECU, and recheck. If symptom goes away, replace original ECU. If battery voltage is not present, repair open in Yellow/Black wire between ECU terminals A25 and B1 and main relay. Check main relay and wiring connectors at main relay.
  8. Using a voltmeter, measure voltage between Brown (+) and Green/White (-) wires on service check connector. If 5 volts are not present, repair short to ground in Brown wire between ECU terminal D4 and service check connector. If 5 volts are present, go to next step.
  9. Turn ignition off. Disconnect ECU "A" connector. Turn ignition on. If CHECK ENGINE light illuminates, repair short to ground in Yellow/Red wire between ECU terminal A13 and CHECK ENGINE light. If CHECK ENGINE light does not illuminate, go to next step.
  10. Substitute a known good ECU, and recheck. If CHECK ENGINE light illuminates or symptom goes away, replace original ECU.
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