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 accelerator pedal position (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 DTC will set and the Reduced Engine Power message will be displayed.
Conditions for Running the DTC
| • | DTCs P1517 or P1518 are not set. |
| • | The ignition is 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 of the above conditions exist 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.
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Using a test lamp reduces the amount of current fed into the signal circuit. The scan tool should display the maximum value for this parameter, 5 volts, even though the actual voltage is higher.
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The TP 2 sensor and the APP 2 sensor share a common 5-volt reference. The 5-volt reference circuits are connected internally within the TAC module. Disconnecting the TAC module will isolate the 5-volt reference circuits.
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The TP sensor 2 and the APP sensor 2 share a common 5-volt reference. A short to voltage on the APP sensor 2 5-volt reference circuit will affect the TP sensor 2 5-volt reference circuit.
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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.
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 | Are DTCs P1515, P1516, or P1518 also set? | -- | Go to Step 3 | |
3 |
Does the scan tool indicate TP sensor 2 voltage within the specified values? | 4.3-4.8 V | Go to Step 4 | Go to Step 7 |
4 | Open the throttle blade to WOT by hand while observing the TP sensor 2 voltage parameter on the scan tool. Does the scan tool indicate TP sensor 2 voltage within the specified values? | 0.13-1 V | Go to Step 5 | Go to Step 7 |
5 |
Did you find and correct the condition? | -- | Go to Step 33 | Go to Step 6 |
6 |
Does the scan tool indicate this DTC failed this ignition? | -- | Go to Step 26 | Go to Diagnostic Aids |
7 | Use a scan tool, in order to observe the TP sensor 2 voltage parameter. Does the scan tool indicate TP sensor 2 voltage at the specified value? | 5 V | Go to Step 8 | Go to Step 12 |
8 | Disconnect the TP sensor harness connector. Does the scan tool indicate TP sensor 2 voltage at the specified value? | 0 V | Go to Step 9 | Go to Step 13 |
9 |
Does the DMM indicate voltage near the specified value? | 5 V | Go to Step 10 | Go to Step 18 |
10 | With a DMM connected between the TP sensor 1 low reference circuit and the TP sensor 2 low reference circuit at the TP sensor harness connector, test for resistance Does the DMM indicate resistance within the specified values? | 0-5 ohms | Go to Step 14 | Go to Step 11 |
11 |
Did you find and correct the condition? | -- | Go to Step 33 | Go to Step 30 |
Does the scan tool indicate TP sensor 2 voltage near the specified value? | 5 V | Go to Step 20 | Go to Step 15 | |
13 |
Did you find and correct the condition? | -- | Go to Step 33 | Go to Step 17 |
14 |
Did you find and correct the condition? | -- | Go to Step 33 | Go to Step 24 |
15 |
Did you find and correct the condition? | -- | Go to Step 33 | Go to Step 16 |
16 | Use a DMM in order to test the TP sensor 2 signal circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 33 | Go to Step 17 |
17 | Use a DMM in order to test for a short between the TP sensor 2 signal circuit and all other TAC module circuits. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to step 33 | Go to Step 30 |
Did you find and correct the condition? | -- | Go to step 33 | Go to Step 19 | |
Did you find and correct the condition? | -- | Go to step 33 | Go to Step 24 | |
20 |
Did you find and correct the condition? | -- | Go to Step 33 | Go to Step 21 |
21 | Use a DMM in order to test the TP sensor 2, 5-volt reference circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 33 | Go to Step 22 |
22 |
Did you find and correct the condition? | -- | Go to Step 33 | Go to Step 23 |
23 | Use a DMM in order to test the APP sensor 2, 5-volt reference circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 33 | Go to Step 24 |
24 | Use a DMM in order to test the TP sensor 2, 5-volt reference circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 33 | Go to Step 25 |
25 | Use a DMM in order to test for a short between the TP sensor 2, 5-volt reference circuit and all other TAC module circuits. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 33 | Go to Step 26 |
26 | Use a DMM in order to test for a short between the APP sensor 2, 5-volt reference circuit and all other TAC module circuits. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 33 | Go to Step 27 |
27 | Use a DMM in order to test the TP sensor 2 signal circuit for high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 33 | Go to Step 28 |
28 | Use a DMM in order to test the TP sensor 2 low reference circuit for resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 33 | Go to Step 29 |
29 | 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 33 | Go to Step 31 |
30 | Inspect for poor connections 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 33 | Go to Step 32 |
31 |
Important: The throttle body and the throttle position sensor assembly should be replaced as a unit. Driveability concerns may result if either is replaced individually. Replace the throttle body assembly. Refer to Throttle Body Assembly Replacement . Did you complete the replacement? | -- | Go to Step 33 | -- |
32 | Replace the TAC module. Refer to Electronic Throttle Actuator Control Module Replacement . Did you complete the replacement? | -- | Go to Step 33 | -- |
33 |
Does the DTC run and pass? | -- | Go to Step 34 | Go to Step 2 |
With a scan tool, observe the stored information, Capture Info. Does the scan tool indicate any DTCs that you have not diagnosed? | -- | System OK | ||
