Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSPLYMOUTH1994SUNDANCE BASE, 2D HATCHBACK, 2.2 D, AUTOMATICREPAIR AND DIAGNOSISENGINE PERFORMANCETESTING & DIAGNOSISENGINE CONTROLS - TESTS W/CODES - 2.5L TBISELF-DIAGNOSTIC TESTSTEST TC-7A - O2S STAYS AT CENTER (DTC 21)
1994 Plymouth Sundance Base, 2D Hatchback, 2.2 D, Automatic
Test TC-7A - O2S Stays At Center (DTC 21)
1994 Plymouth Sundance Base, 2D Hatchback, 2.2 D, AutomaticSECTION Test TC-7A - O2S Stays At Center (DTC 21)
NOTE:
For circuit and connector terminal identification, see CONNECTOR IDENTIFICATION TABLE. For wiring diagrams, see WIRING DIAGRAMS
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- Start engine. Allow engine to run until normal operating temperature is reached. Using DRB, set engine speed to 1500 RPM. Using DRB, read oxygen sensor state. If oxygen sensor is locked at center, go to step 4). If oxygen sensor is not locked at center, wiggle oxygen sensor connector and wiring harness while watching DRB display.
- If oxygen sensor was locked at center at any time, inspect all related wiring and connectors and repair as necessary. Perform TEST VER-2 . If oxygen sensor was not locked at center at any time, condition required to set trouble code is not present at this time. The O2S STAYS AT CENTER trouble code sets if oxygen sensor output voltage stays at .5 volt for 1.5 minutes with engine temperature more than 170°F (77°C) and engine running for 2 minutes. Possible causes are: open oxygen sensor circuit or oxygen sensor failure. Go to next step.
- Inspect all related wiring and connectors and repair as necessary. Perform TEST VER-2. If no problems were found with wiring and connectors, see INACTIVE TROUBLE CODE CONDITION. Perform TEST VER-2.
- Disconnect oxygen sensor connector. Put DRB in ohmmeter mode. Using DRB, check resistance of Black/Light Blue wire at oxygen sensor connector harness side. If resistance is more than 5 ohms, repair open in Black/Light Blue wire. Perform TEST VER-2.
- If resistance is less than 5 ohms, connect a jumper wire between oxygen sensor Black/Dark Green wire (Dark Green/White on Dakota) and battery positive terminal. Using DRB, read oxygen sensor voltage. If voltage is more than one volt, replace oxygen sensor. Perform TEST VER-2 .
- If oxygen sensor voltage is less than one volt, turn ignition off. Disconnect Powertrain Control Module (PCM) connector. Disconnect jumper wire between oxygen sensor Black/Dark Green wire (Dark Green/White wire on Dakota) and battery positive terminal.
- Using an external ohmmeter, check resistance of oxygen sensor Black/Dark Green wire (Dark Green/White wire on Dakota) between oxygen sensor connector harness side and PCM connector terminal No. 41. If resistance is less than 5 ohms, replace PCM. Perform TEST VER-2. If resistance is more than 5 ohms, repair open in Black/Dark Green wire (Dark Green/White wire on Dakota). Perform TEST VER-2.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.