Information Sensors

ENGINE COOLANT TEMPERATURE (ECT) SENSOR
Diagnostic Trouble Codes (DTC) 14 or 15 indicates a failure in the engine coolant temperature sensor circuit.
Most scan tools display engine temperature in degrees centigrade. After engine is started, the temperature should rise steadily to about 90° C then stabilize when thermostat opens.
Powertrain Controls - ECM/PCM
DTC 15

MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR
Diagnostic Trouble Codes (DTC) 33 or 34 indicates a failure in the MAP sensor circuit.
Powertrain Controls - ECM/PCM
Powertrain Controls - ECM/PCM
Also, if there is no DTC and to check the MAP sensor, refer to MANIFOLD ABSOLUTE PRESSURE OUTPUT CHECK.
MAP Sensor Output Diagnosis

OXYGEN SENSOR (O2S)
Diagnostic Trouble Code (DTC) 13 indicates an open in the Oxygen Sensor (O2S) circuit. DTC 44 indicates a low voltage in the Oxygen Sensor (O2S) circuit. DTC 45 indicates a high voltage in the Oxygen Sensor (O2S) circuit. If a DTC is set, the engine will always run in the "Open Loop" mode. On heated oxygen sensors value will drop lower towards 0 as the sensor heater inside the sensor warms up.
Normal scan voltage varies between 100 mV to 999 mV (0.1 and 1.0 volt) while in "Closed Loop." DTC 13 sets in one minute if voltage remains between 0.35 and 0.55 volt, but the system will go "Open Loop" in about 15 seconds.
DTC 13
Using the scan tool, observe the long term fuel trim values at different RPM and air flow conditions to determine when DTC 44 or DTC 45 may have been set. If the condition for DTC 44 exists, the long term fuel trim values will be around 150. If the condition for DTC 45 exists, the long term fuel trim values will be around 115.
Powertrain Controls - ECM/PCM
Powertrain Controls - ECM/PCM
If the heated oxygen sensor pigtail wiring, connector or terminal is damaged, the entire oxygen sensor assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In order for the sensor to function properly, it must have provided to it a clean air reference. This clean air reference is obtained by way of the oxygen sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degraded oxygen sensor performance.

THROTTLE POSITION (TP) SENSOR
When a Diagnostic Trouble Codes (DTC) 21 or 22 is set, the Powertrain Control Module (PCM) will use an artificial value for throttle position and some engine performance will return.
A broken TP sensor can cause intermittent bursts of fuel from the injector(s) and an unstable idle because the PCM thinks the throttle is moving.
A scan tool reads throttle position in volts and should read about 0.60 volt with the throttle closed, ignition "ON" or at idle. Voltage should increase at a steady rate as throttle is moved toward Wide Open Throttle (WOT).
Scan TP signal while depressing accelerator pedal with engine stopped and ignition "ON." Display should vary from below 0.85 volt (850 mV) when throttle was closed, to over 4.5 volts (4500 mV) when throttle is held at wide open throttle position.
Powertrain Controls - ECM/PCM
Powertrain Controls - ECM/PCM

TP Sensor Output
This check should be performed when TP sensor attaching parts have been replaced. A TECH 1 scan tool can be used to read the TP signal output voltage, or:
1. Connect digital voltmeter J 39200 or equivalent, from TP sensor connector terminal "B" (BLK wire) to terminal "C" (DK BLU wire). Jumpers for terminal access can be made using terminals "1214836" and "12014837".
2. With ignition "ON," engine stopped, the TP sensor voltage should be less than 0.85 volt if more than 0.85 volt verify free throttle movement. If still more than 1.25 volts, replace TP sensor.
3. Remove the voltmeter and jumpers, reconnect the TP sensor connector to the sensor.

VEHICLE SPEED SENSOR (VSS)
The vehicle speed sensor circuit diagnosis is in TRANSMISSIONS AND CONTROL SYSTEMS. Scan tool reading should closely match speedometer readings, with the drive wheels turning.