Diagnosis & Repair Procedure
NOTE:
For better performance and results of this diagnostic procedure, usage of appropriate wiring diagram is recommended. See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS
article in ELECTRICAL.
NOTE:
Perform all voltage and resistance tests using a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance, unless stated otherwise in test procedure. Use an ohmmeter to isolate wiring harness shorts or opens.
- If engine system check has been performed, go to next step. If engine system check has not been performed, perform A-4: ENGINE SYSTEM CHECK under SYSTEM TESTS, then go to next step.
- Turn ignition switch to LOCK position. Locate ECM 26-pin harness connector C51-3 under instrument panel, behind glove box. See Figure . Turn ignition switch to ON position. Backprobe and measure voltage between ECM harness connector C51-3 terminals No. 8 (Red/White wire) and No. 14 (White/Red wire). See Figure . Voltage should be 0.2 volt or more with ignition in ON position, and 4.6 volts or less with engine running at idle speed. If voltage readings are not as specified, go to next step. If voltage readings are as specified, problem is intermittent. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES article. After repair, repeatDTC CONFIRMATION TEST .
- Turn ignition switch to LOCK position. Disconnect MAP sensor 3-pin harness connector C58, located on air intake plenum. See Figure . Check MAP sensor and harness connector terminals for corrosion or poor connection. If connector terminals are faulty, repair as necessary and repeat DTC CONFIRMATION TEST . If connector terminals are okay, perform MAP sensor component test. See MANIFOLD ABSOLUTE PRESSURE SENSOR under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING article. If MAP sensor is faulty, replace MAP sensor. See MANIFOLD ABSOLUTE PRESSURE SENSOR under ENGINE SENSORS & SWITCHES in REMOVAL & INSTALLATION article. After repair, repeatDTC CONFIRMATION TEST . If MAP sensor is okay, check Red/White wire, Blue/White wire and White/Red wire for open or short circuit between ECM and MAP sensor. If short or open circuit is found, repair as necessary and repeatDTC CONFIRMATION TEST . If short or open circuit is not found, substitute ECM with a known good unit and repeat DTC CONFIRMATION TEST .