Circuit Description
The throttle position (TP) sensor is mounted on the throttle body assembly. The sensor is actually two individual TP sensors within one housing. Two separate signal, low reference, and 5 volt reference circuits are used to connect the TP sensor assembly to the throttle actuator control (TAC) module. The 2 sensors have opposite functionality. The TP sensor 1 signal voltage is pulled up to reference voltage as the throttle opens, from below 1.0 volt at closed throttle to above 3.5 volts at wide open throttle (WOT). The TP sensor 2 signal voltage is pulled down to low reference from around 3.8 volts at closed throttle to below 1.0 volt at WOT. TP sensor 1 and APP sensor 1 share a 5-volt reference circuit that are connected within the TAC module. TP sensor 2 and APP sensor 2 share a 5-volt reference circuit that are connected within the TAC module. If an out of range condition is detected with the TP sensor 2, this diagnostic trouble code (DTC) will set and the Reduced Engine Power message will be displayed.
Conditions for Running the DTC
| • | DTC P1518 are not set. |
| • | The ignition switch in the crank or run position. |
| • | The ignition voltage is greater than 5.23 volts. |
Conditions for Setting the DTC
| • | The TP sensor 2 voltage is less than 0.13 volts or greater than 4.87 volts. |
| • | All above conditions are present for less than 1 second. |
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 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. |
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 the TAC module connectors for signs of water intrusion. When this occurs, multiple DTCs could be set with no circuit or component conditions found during diagnostic testing. |
| • | When the TAC module detects a condition within the TAC system, more than one TAC system related DTC may set. This is due to the many redundant tests run continuously on this system. Locating and repairing one individual condition may correct more than one DTC. Disconnecting components during testing may set additional DTCs. Keep this in mind when reviewing the stored information, Capture Info. |
| • | If this DTC is determined to be intermittent, refer to Intermittent Conditions . |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Powertrain Control Module Connector End Views or Engine Controls Connector End Views | ||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |
2 |
Is the TP sensor 2 voltage within the specified range? | 0.28-0.81 V | Go to Step 3 | Go to Step 7 |
3 |
Is the TP sensor 2 voltage parameter more than the specified value? | 4.60 V | Go to Step 7 | Go to Step 4 |
4 |
Did you find and correct the condition? | -- | Go to Step 30 | Go to Step 5 |
5 |
Did you find and correct the condition? | -- | Go to Step 30 | Go to Step 6 |
6 |
Does the scan tool indicate this DTC failed this ignition? | -- | Go to Step 25 | Go to Diagnostic Aids |
7 |
Is the voltage within the specified range? | 3.94-6.06 V | Go to Step 12 | Go to Step 8 |
8 |
Did you find and correct the condition? | -- | Go to Step 30 | Go to Step 9 |
9 | Test the TP sensor 2 signal circuit for an open or high resistance with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 30 | Go to Step 10 |
10 | Test the TP sensor 2 signal circuit for a short to ground with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 30 | Go to Step 11 |
11 |
Did you find and correct the condition? | -- | Go to Step 30 | Go to Step 26 |
12 | Measure the voltage from the TP sensor 2, 5-volt reference circuit to a good ground with a DMM. Refer to Circuit Testing in Wiring Systems. Is the voltage within the specified range? | 4.54-5.21 V | Go to Step 22 | Go to Step 13 |
13 | Is the voltage more than the specified value? | 5.21 V | Go to Step 14 | Go to Step 16 |
14 |
Did you find and correct the condition? | -- | Go to Step 30 | Go to Step 15 |
15 |
Did you find and correct the condition? | -- | Go to Step 30 | Go to Step 20 |
16 | Disconnect the APP sensor. Is the voltage less than the specified value? | 4.54 V | Go to Step 17 | Go to Step 28 |
17 |
Did you find and correct the condition? | -- | Go to Step 30 | Go to Step 18 |
18 | Test the TP sensor 2, 5-volt reference circuit for a short to ground with a DMM. Did you find and correct the condition? | -- | Go to Step 30 | Go to Step 19 |
19 | Test the APP sensor 2, 5-volt reference circuit for a short to ground with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 30 | Go to Step 21 |
20 | Test for a short between the TP sensor 2, 5-volt reference circuit and all other TAC module circuits with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 30 | Go to Step 21 |
21 | Test for a short between the APP sensor 2, 5-volt reference circuit and all other TAC module circuits with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 30 | Go to Step 26 |
22 |
Is the TP sensor 2 parameter near the specified value? | 0 V | Go to Step 24 | Go to Step 23 |
23 |
Did you find and correct the condition? | -- | Go to Step 30 | Go to Step 26 |
24 | Inspect for an intermittent and for a poor connection at the throttle body harness connector. Refer to Testing for Intermittent Conditions and Poor Connections and Repairing Connector Terminals in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 30 | Go to Step 27 |
25 | Inspect for an intermittent and for a poor connection at the APP sensor harness connector. Refer to Testing for Intermittent Conditions and Poor Connections and Repairing Connector Terminals in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 30 | Go to Step 28 |
26 | Inspect for an intermittent and for a poor connection at the TAC module harness connector. Refer to Testing for Intermittent Conditions and Poor Connections and Repairing Connector Terminals in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 30 | Go to Step 29 |
27 | Replace the throttle body assembly. Refer to Throttle Body Assembly Replacement . Did you complete the replacement? | -- | Go to Step 30 | -- |
28 | Replace the APP sensor. Refer to Accelerator Pedal Position Sensor Replacement . Did you complete the replacement? | -- | Go to Step 30 | -- |
29 | Replace the TAC module. Refer to Electronic Throttle Actuator Control Module Replacement . Did you complete the replacement? | -- | Go to Step 30 | -- |
30 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 31 |
Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | ||
