Circuit Description
The throttle position (TP) sensor is mounted on the throttle body assembly. The sensor is actually 2 individual TP sensors within 1 housing. Two separate signal circuits, low reference circuits, and 5-volt reference circuits are used in order 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 when the throttle opens, from below 1 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 volt at WOT. TP sensor 1 and APP sensor 1 share a 5-volt reference circuit that is connected within the TAC module. TP sensor 2 and APP sensor 2 share a 5-volt reference circuit that is connected within the TAC module. If an out of range condition is detected with the TP sensor 1, this DTC will set and the Reduced Engine Power message will be displayed.
Conditions for Running the DTC
| • | DTC P1518 is not set. |
| • | The ignition switch is in the crank or the run position. |
| • | The ignition voltage is greater than 5.23 volts. |
Conditions for Setting the DTC
| • | The TP sensor 1 signal voltage is less than 0.13 volts or greater than 4.87 volts. |
| • | The above condition is 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 number below refers to the step number on the diagnostic table.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic References: 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 |
Does the scan tool indicate that the TP sensor 1 voltage is within the specified values? | 0.13-0.67 V | Go to Step 5 | Go to Step 3 |
3 |
Is the TP sensor 2 voltage within the specified range? | 0.28-0.81 V | Go to Step 9 | Go to Step 4 |
4 | Is DTC P1518 also set? | -- | Go to Step 9 | |
5 | Open the throttle blade to wide open throttle (WOT) by hand while observing the TP sensor 1 voltage parameter on the scan tool. Does the scan tool indicate that the TP sensor 1 voltage is within the specified values? | 4.09-4.87 V | Go to Step 4 | Go to Step 9 |
6 |
Did you find and correct the condition? | -- | Go to Step 32 | Go to Step 7 |
7 |
Did you find and correct the condition? | -- | Go to Step 32 | Go to Step 8 |
8 |
Does the scan tool indicate this DTC failed this ignition? | -- | Go to Step 27 | Go to Diagnostic Aids |
9 |
Does the DMM indicate voltage within the specified values? | 3.94-6.06 V | Go to Step 14 | Go to Step 10 |
10 |
Did you find and correct the condition? | -- | Go to Step 32 | Go to Step 11 |
11 | Test the TP sensor 1 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 32 | Go to Step 12 |
12 | Test the TP sensor 1 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 32 | Go to Step 13 |
13 |
Did you find and correct the condition? | -- | Go to Step 32 | Go to Step 28 |
14 | Test the TP sensor 1 5-volt reference circuit for voltage with a DMM. Does the DMM indicate voltage within the specified values? | 3.94-6.06 V | Go to Step 24 | Go to Step 15 |
15 | Does the DMM indicate voltage greater than the specified value? | 6.06 V | Go to Step 16 | Go to Step 18 |
16 |
Did you find and correct the condition? | -- | Go to Step 32 | Go to Step 17 |
17 |
Did you find and correct the condition? | -- | Go to Step 32 | Go to Step 22 |
18 | Disconnect the APP sensor. Does the DMM indicate voltage less than the specified value? | 3.94 V | Go to Step 19 | Go to Step 30 |
19 |
Did you find and correct the condition? | -- | Go to Step 32 | Go to Step 20 |
20 | Test the TP sensor 1 5-volt reference circuit for a short to ground with a DMM. Did you find and correct the condition? | -- | Go to Step 32 | Go to Step 21 |
21 | Test the APP sensor 1 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 32 | Go to Step 22 |
22 | Test for a short between the TP sensor 1 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 32 | Go to Step 23 |
23 | Test for a short between the APP sensor 1 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 32 | Go to Step 28 |
24 |
Does the scan tool indicate voltage near the specified value? | 0 V | Go to Step 26 | Go to Step 25 |
25 |
Did you find and correct the condition? | -- | Go to Step 32 | Go to Step 28 |
26 | Inspect for poor 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 32 | Go to Step 29 |
27 | Inspect for poor connections at the APP module 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 32 | Go to Step 30 |
28 | Inspect for a poor connection at the TAC module 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 32 | Go to Step 31 |
29 | Replace the throttle body assembly. Refer to Throttle Body Assembly Replacement . Did you complete the replacement? | -- | Go to Step 32 | -- |
30 | Replace the APP sensor. Refer to Accelerator Pedal Position Sensor Replacement . Did you complete the replacement? | -- | Go to Step 32 | -- |
31 | Replace the TAC module. Refer to Electronic Throttle Actuator Control Module Replacement . Did you complete the replacement? | -- | Go to Step 32 | -- |
32 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 33 |
Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | ||
