Circuit Description
The commanded throttle position (TP), based on accelerator pedal position (APP) and possibly other limiting factors, is compared to the actual throttle position. The TP values should be within a calibrated range of each other. The throttle actuator control (TAC) module monitors the commanded and actual throttle position. This DTC sets if the TAC module detects the condition and send the message to the powertrain control module (PCM) across serial data.
Conditions for Running the DTC
| • | The ignition is in the crank or run position. |
| • | DTC P1518 is not present. |
Conditions for Setting the DTC
The TAC module detects that the commanded and actual throttle positions are not within a calibrated range of each other or the TAC module cannot determine throttle position or both TP sensors are invalid.
Action Taken When the DTC Sets
| • | The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails. |
| • | The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. |
| • | 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 emission related diagnostic. |
| • | Clear the MIL and the DTC with a scan tool. |
Diagnostic Aids
Inspect for the following:
Important: Verify that the starting and charging systems are operating properly. Low system voltage causes this DTC to set.
If you Do NOT find any trouble, check for mechanical conditions or for binding that may be temperature related. Components may not move freely in extreme heat or cold due to the presence of contaminants or ice formation.
If the condition is intermittent, refer to Intermittent Conditions .
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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If the TP indicated angle does not follow the movement of the throttle blade, and the TP sensor DTCs are not set, there is a mechanical condition with the throttle shaft or the TP sensor. Replace the throttle body assembly. Re-install the air inlet duct after repairs are completed.
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When the PCM detects a condition within the electronic throttle control (ETC) system other DTCs may set due to the many redundant tests run continuously on this system. Locating and repairing 1 individual condition may correct more than 1 DTC. Keep this in mind when reviewing captured DTC info.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |
2 |
Important: If you came from 1 of the following DTC tables continue with this table and go to step 3. Is DTC P1120, P1220 or P1221 set? | -- | Go to Step 3 | |
Does the TP sensor 1 and 2 angle increase to near the specified value as the pedal is depressed and decrease as the pedal is released? | 100% | Go to Diagnostic Aids | Go to Step 4 | |
4 |
Does the voltage measure within the specified values? | 7.5-8.5 V | Go to Step 15 | Go to Step 5 |
5 | Measure the voltage on each throttle actuator circuit , motor high and motor low, using a DMM that is connected to a good ground. Is any voltage present? | -- | Go to Step 9 | Go to Step 6 |
6 | Test for an open in each throttle actuator circuit , motor high and motor low. Refer to Circuit Testing in Wiring Systems. Did you find a condition? | -- | Go to Step 10 | Go to Step 7 |
7 |
Did you find a condition? | -- | Go to Step 11 | Go to Step 8 |
8 | Test for continuity between each throttle actuator circuit , motor high and motor low, and all other circuits in the TAC module connector. Refer to Circuit Testing in Wiring Systems. Is continuity indicated? | -- | Go to Step 12 | Go to Step 13 |
9 | Test for a short to voltage on the affected throttle actuator circuit. Refer to Circuit Testing in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 14 |
10 | Repair the open or high resistance on the affected throttle actuator circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 17 | -- |
11 | Repair the short to ground on the affected throttle actuator circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 17 | -- |
12 | Repair the circuits that are shorted together. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 17 | -- |
13 | Inspect for poor connections at the TAC module. 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 17 | Go to Step 14 |
14 | Replace the TAC module. Refer to Accelerator Pedal Position Sensor Replacement . Did you complete the replacement? | -- | Go to Step 17 | -- |
15 | Inspect for poor connections at the TAC. 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 17 | Go to Step 16 |
16 | Replace the throttle body of the TAC assembly. Refer to Throttle Body Assembly Replacement . Did you complete the replacement? | -- | Go to Step 17 | -- |
17 |
Does the DTC run, and pass? | -- | Go to Step 18 | Go to Step 2 |
With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | ||
