Circuit Description
The Throttle Position (TP) Sensor provides a voltage signal which changes relative to the throttle blade angle.
The TP sensor signal voltage varies from about 0.5 volt at idle to about 4.5 volts at Wide Open Throttle (WOT). The TP sensor signal is used by the TCM for most of the TCM control outputs.
Each time the voltage drops below 1.25 volts and stops, the TCM assumes this value as the 0 throttle angle. The TCM measures the percent throttle from this point on.
Conditions for Setting the DTC
| • | The engine is running. |
| • | TP Sensor Signal is less than 0.2 volts for greater than 1 second. |
Action Taken When the DTC Sets
Important:: The scan tool will not indicate a default value.
| • | The TCM does not illuminate the MIL. |
| • | The TCM commands maximum line pressure. |
| • | The TCM uses 35% TP as a default. |
| • | The TCM inhibits 4th gear if in hot mode. |
| • | DTC 22 is stored in TCM history. |
Conditions for Clearing the DTC
| • | A scan tool can clear the DTC from TCM history. |
| • | The TCM cancels the DTC default actions when the fault no longer exists and the ignition is OFF long enough in order to power down the TCM. |
Diagnostic Aids
The scan tool reads the throttle position in volts. The TP should read about 0.45 to 0.85 volt with the throttle closed and the ignition switch turned ON or at idle. The voltage should increase at a steady rate as the throttle is moved toward the Wide Open Throttle (WOT).
An open or short to ground in the 5 volt reference circuit or the TP sensor signal circuit results in a DTC 22.
Scan the TP sensor while depressing the accelerator pedal with the engine stopped and the ignition ON. The display should vary from below 1.25 volts (1250 mV) when the throttle was closed, to over 4.5 volts (4500 mV) when the throttle is held at the Wide Open Throttle (WOT) position.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
If the TP signal measures less than 0.2 volt, then the fault exists.
-
This test simulates the DTC 21 (high voltage). If the VCM recognizes the high signal voltage, the VCM and the wiring harness are okay.
-
This test simulates a high signal voltage in order to check for an open in the TP signal circuit.
-
This step checks the 5 volt reference circuit for an open, short to ground, or a poor connection, or a faulty TCM.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 |
Important:: Before clearing the DTC's, use the Scan Tool in order to record the freeze frame and the failure records for reference because the Clear Info function loses the data. Was the On-Board Diagnostic (OBD) System Check performed? | -- | ||
Does the Scan Tool display a TP signal less than the specified value? | 0.2 V | |||
Does the Scan Tool display a TP signal greater than the specified value? | 4.0 V | |||
Probe the TP sensor signal circuit with a test lamp connected to the B +. Does the Scan Tool display a throttle position signal greater than the specified value? | 4.0 V | |||
5 | The DTC is intermittent. If no additional DTC's are stored, refer to the Diagnostic Aids. If additional DTC's are stored, refer to those tables. Are any additional DTC's set? | -- | Go to The Applicable DTC Table | |
Check for an open In the 5 volt reference circuit. Refer to General Electrical Diagnosis . Was an open condition found? | -- | |||
7 | Check the 5 volt reference for a short to the ground. Refer to General Electrical Diagnosis . Was a short to ground condition found? | -- | ||
8 | Check the TP sensor signal circuit for an open. Refer to General Electrical Diagnosis . Was an open condition found? | -- | ||
9 | Check the TP sensor signal circuit for a short to the ground. Refer to General Electrical Diagnosis . Was a short to ground condition found? | -- | ||
10 | Check for a faulty connection at the TCM. Was a condition found? | -- | ||
11 | Repair the circuit as necessary. Refer to Wiring Repairs . Is the repair complete? | -- | -- | |
12 | Replace the faulty TP sensor. Refer to Throttle Position Sensor Replacement . Is the replacement complete? | -- | -- | |
13 |
Important:: If the TCM is faulty, re-use the PROM (Mem-cal). Refer to DTC 51 PROM Error TCM Replacement. Replace the TCM. Is the replacement complete? | -- | -- | |
14 |
Is the Scan Tool TP sensor voltage greater than the specified value? | 0.2 V | System OK |
