The commanded throttle position is compared to the actual throttle position. Both values should be within a calibrated range of each other. The engine control module (ECM) continuously monitors the commanded and actual throttle positions. If the ECM detects that the difference in these values are greater than the calibrated range, DTC 1516 will set.
This diagnostic procedure supports the following DTC:
DTC P1516 Throttle Actuator Control (TAC) Module Throttle Actuator Position Performance
• | The ignition is ON. |
• | The ignition voltage is greater than 8 volts. |
• | The system is not in Battery Saver Mode. |
• | The engine is running. |
• | DTC P0068 is not set. |
• | DTC P1516 runs continuously when the above conditions are met. |
The difference between the predicted and the actual throttle position is more than a calibrated amount for more than 0.5 second.
• | 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 and/or the Failure Records. |
• | The control module commands the TAC system to operate in the Reduced Engine Power mode. |
• | A message center or an indicator displays Reduced Engine Power. |
• | Under certain conditions the control module commands the engine OFF. |
• | 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. |
The numbers below refer to the step numbers on the diagnostic table.
The throttle valve is spring loaded in a slightly open position and should move in either direction without binding. The throttle valve should always be under spring pressure.
When the ignition is turned ON, the ECM operates the throttle control motor to verify the integrity of the system prior to start-up. This can be seen by the momentary flash of the test lamp as the ignition is turned ON.
Step | Action | Yes | No | ||||||
---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Controls Connector End Views or Engine Control Module Connector End Views | |||||||||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | |||||||
2 | Are DTCs P0120, P0220, P2120, P2125, P2135, P2138, P1275 and P1280 also set? | Go to Step 3 | |||||||
3 |
Important: The throttle angle and pedal angle may not correspond during this procedure.
Does the TP sensor 1 and 2 angle parameters increase as the pedal is applied and decrease as the pedal is released? | Go to Step 4 | Go to Step 5 | ||||||
4 |
Did the DTC fail this ignition? | Go to Step 5 | Go to Testing for Intermittent Conditions and Poor Connections | ||||||
5 |
Does the test lamp illuminate on both sides of the fuse? | Go to Step 6 | Go to Step 16 | ||||||
6 |
Does the test lamp illuminate on both sides of the fuse? | Go to Step 22 | Go to Step 7 | ||||||
7 |
Does the test lamp illuminate? | Go to Step 8 | Go to Step 23 | ||||||
Did you find any of these conditions with the throttle body? | Go to Step 24 | Go to Step 9 | |||||||
9 |
Important: The test lamp may momentarily flash when testing these circuits. This is considered normal.
Did the test lamp illuminate and remain illuminated on either circuit? | Go to Step 13 | Go to Step 10 | ||||||
10 |
Important: The test lamp may momentarily flash when testing these circuits. This is considered normal. Probe the TAC motor control 1 and 2 circuits with the test lamp connected to battery positive. Did the test lamp illuminate and remain illuminated on either circuit? | Go to Step 14 | Go to Step 11 | ||||||
Does the test lamp flash ON and then turn OFF? | Go to Step 12 | Go to Step 15 | |||||||
12 |
Does the test lamp flash ON and then OFF? | Go to Step 18 | Go to Step 15 | ||||||
13 |
Does the test lamp illuminate? | Go to Step 20 | Go to Step 19 | ||||||
14 |
Does the test lamp illuminate? | Go to Step 21 | Go to Step 19 | ||||||
15 |
Did you find and correct the condition? | Go to Step 26 | Go to Step 19 | ||||||
16 | Test the ETC ignition 1 voltage circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 26 | Go to Step 17 | ||||||
17 | Test the motor control 1 circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 26 | Go to Step 24 | ||||||
18 | Test for a poor connection or terminal tension at the throttle body connector. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 26 | Go to Step 24 | ||||||
19 | Test for a poor connection or terminal tension at the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 26 | Go to Step 22 | ||||||
20 | Repair the short to voltage on the circuit where the test lamp remained illuminated. Refer to Wiring Repairs s. Did you complete the repair? | Go to Step 26 | -- | ||||||
21 | Repair the short to ground on the circuit where the test lamp remained illuminated. Refer to Wiring Repairs . Did you complete the repair? | Go to Step 26 | -- | ||||||
22 | Repair the short to voltage on the ETC ignition 1 voltage circuit. Refer to Wiring Repairs . Did you complete the repair? | Go to Step 26 | -- | ||||||
23 | Repair the open or the high resistance in the ignition 1 voltage circuit. Refer to Wiring Repairs . Did you complete the repair? | Go to Step 26 | -- | ||||||
24 | Replace the throttle body assembly. Refer to Throttle Body Assembly Replacement . Did you complete the replacement? | Go to Step 26 | -- | ||||||
25 | Replace the ECM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | Go to Step 26 | -- | ||||||
26 |
Did the DTC fail this ignition? | Go to Step 2 | Go to Step 27 | ||||||
27 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | System OK |