The throttle position (TP) sensor is used by the powertrain control module (PCM) in order to determine the throttle plate angle for various engine management systems. The TP sensor is a potentiometer type sensor with 3 circuits:
• | A 5-volt reference circuit |
• | A low reference circuit |
• | A signal circuit |
Rotation of the TP sensor rotor from the closed throttle position to the wide open throttle (WOT) position provides the PCM with a signal voltage from less than 1.0 volt to more than 4 volts through the TP sensor signal circuit. If the PCM detects an intermittent excessively low signal voltage, this diagnostic trouble code (DTC) will set.
• | The ignition is ON. |
• | DTCs P1635 or P1639 are not set. |
The TP sensor intermittently indicates a throttle position signal of less than 0.15 volt.
• | The control module stores the DTC information into memory when the diagnostic runs and fails. |
• | The malfunction indicator lamp (MIL) will not illuminate. |
• | The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records. |
• | The driver information center, if equipped, may display a message. |
• | A current DTC Last Test Failed clears when the diagnostic runs and passes. |
• | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic. |
• | Clear the DTC with a scan tool. |
The number below refers to the step number on the diagnostic table.
Step | Action | Yes | No |
---|---|---|---|
Schematic Reference: Engine Controls Schematics | |||
1 | Did you perform the Diagnostic System Check-Engine Controls? | Go to Step 2 | |
2 |
Did you find and correct the condition? | Go to Step 8 | Go to Step 3 |
3 |
Did you find and correct the condition? | Go to Step 8 | Go to Step 4 |
4 | Inspect for faulty connections at the TP sensor harness connector. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 8 | Go to Step 5 |
5 | Inspect for faulty connections at the harness connector of the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 8 | Go to Step 6 |
Did you record a MAX value of OL or record a MIN value of 0 ohms in either test? | Go to Step 7 | Go to Intermittent Conditions | |
7 | Replace the TP sensor. Refer to Throttle Position Sensor Replacement . Did you complete the replacement? | Go to Step 8 | -- |
8 |
Did the DTC fail this ignition | Go to Step 2 | Go to Step 9 |
9 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | System OK |