Powertrain Controls - ECM/PCM

DTC 17 Chart:

Heated Oxygen Sensor Circuit:

CIRCUIT DESCRIPTION
The PCM supplies a voltage of about 0.45 volt between terminals "F14" and "F13". (If measured with a 10 megohm digital voltmeter, this may read as low as 0.32 volt). The front oxygen sensor varies the voltage within a range of about 1 volt if the exhaust is rich, down through about 0.10 volt if the exhaust is lean. The sensor is like an open circuit and produces no voltage when it is below 360.5°C (680.9°F). An open or cold front oxygen sensor causes "Open Loop" operation.

DTC 17 WILL SET WHEN
- No DTC(s) 14, 15,21,22,26,27 and 119.
- Engine is running.
- Greater than 800 RPM.
- Engine temperature is within operating range, above 82.5°C (180.5°F).
- Front HO2S (Bank 2) voltage is steady between 0.3 and 0.6 volt.
- Throttle switch open.
- -Throttle angle is between 5.4° and 25°.
- All above conditions must be present for at least 64 seconds. Action Taken (PCM WILL DEFAULT TO):
- With a current DTC 17 set, the PCM will illuminate the Malfunction Indicator Lamp (MIL) (Service Engine Soon).
- Uses Bank 1 HO2S for fuel control (to maintain "Closed Loop" operation). DTC 17 Will Clear When: The fault no longer exists.

DTC CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.

1. Voltage on Tech 1 PCM data parameter should fluctuate above 0.6 volt and below 0.3 volt. If voltage remains above 0.6 volt, check CKT 412 for a short to voltage. If voltage remains below 0.3 volt, check CKT 412 for a short to ground.
2. Measuring voltage with a voltmeter will isolate a sensor/wiring problem from a PCM problem. If voltage fluctuates above 0.6 volt and below 0.3 volt, the fault is with the PCM. If voltage remains below 0.3 volt, check CKT 412 for a short to ground or CKT 413 for a short to voltage. If voltage remains above 0.6 volt, check CKT 412 for a short to voltage. If voltage remains between 0.3 volt and 0.6 volt, check CKT 412 and CKT 413 for an open.

DIAGNOSTIC AIDS
An intermittent may be caused by a poor wire connection, rubbed through wire insulation, or a wire broken inside the insulation.
Check for:

Poor connection or damaged harness
Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connections or damaged harness. Intermittent Test - With Tech 1, scan rear HO2S signal voltage while moving related connectors and harnesses, with engine running at part throttle in "Closed Loop." If the failure is induced, the HO2S signal voltage will change from its normal fluctuating voltage to a fixed voltage around 450 mV.