DTC P1271 Without RPO CTF
| Table 1: | APP Sensor Position Table |
Circuit Description
The accelerator pedal position (APP) sensor is mounted on the accelerator pedal control assembly. The sensor is made up of 3 individual sensors within 1 housing. Three separate signal, low reference, and 5-volt reference circuits are used in order to interface the APP sensor with the engine control module (ECM). Each sensor has a unique functionality to determine pedal position as shown in the table below. The ECM uses the APP sensor to determine the amount of acceleration or deceleration desired by the person driving the vehicle via fuel injector control. This DTC sets if the ECM determines an out of range condition with the APP sensor.
APP Sensor | Actual Pedal Position | % Depressed as Observed on a Scan Tool | Voltage as Observed on a Scan Tool |
|---|---|---|---|
1 | Pedal at rest | 0 | .52 - .80 |
1 | Pedal at full travel | 100 | 2.12 - 2.78 |
2 | Pedal at rest | 0 | 4.25 - 4.53 |
2 | Pedal at full travel | 100 | 2.24 - 2.93 |
3 | Pedal at rest | 0 | 3.95 - 4.13 |
3 | Pedal at full travel | 100 | 2.69 - 3.16 |
Conditions for Running the DTC
| • | The ignition switch is in the crank or run position. |
| • | The ignition voltage is between 7-16 volts. |
Conditions for Setting the DTC
| • | The APP sensor 1 and APP sensor 2 are more than 10 percent out of range of each other. |
| • | All of the above conditions present for less than 1 second. |
Action Taken When the DTC Sets
| • | The control module stores the DTC information into memory when the diagnostic runs and fails. |
| • | The malfunction indicator lamp (MIL) will not illuminate. |
| • | If one or more APP sensor DTCs are set for a single APP sensor, the control module will use the remaining 2 APP sensors to calculate throttle response. |
| • | If certain multiple APP sensor DTCs are set for more than one APP sensor, the following occurs: |
| - | The control module commands Reduced Engine Power mode. |
| - | The APP indicated angle is limited to a predetermined value to limit the amount of throttle control. |
| • | If all 3 APP sensors are out of range, the APP indicated angle is limited to 0 percent. The control module only allows the engine to idle. |
Conditions for Clearing the DTC
| • | A current DTC Last Test Failed clears when the diagnostic runs and passes. |
| • | Clear the DTC with a scan tool. |
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 |
Does the DTC fail this ignition? | -- | Go to Step 4 | Go to Step 3 |
3 |
Did this DTC fail this ignition, during the above test ? | -- | Go to Step 4 | Go to Intermittent Conditions |
4 | Is DTC P1272 also set? | -- | Go to Step 6 | Go to Step 5 |
5 | Is DTC P1273 also set? | -- | Go to Step 9 | -- |
6 |
Does the test lamp illuminate? | -- | Go to Step 7 | Go to Step 13 |
7 | With a test lamp connected to ground, test for voltage at the APP sensor 2 signal circuit Does the test lamp illuminate? | -- | Go to Step 8 | Go to Step 14 |
8 | Connect a test lamp between the APP sensor 2, 5-volt reference circuit and the APP sensor 2 low reference circuit. Does the test lamp illuminate? | -- | Go to Step 18 | Go to Step 15 |
9 |
Does the test lamp illuminate? | -- | Go to Step 10 | Go to Step 16 |
10 | Connect the test lamp between the APP sensor 1, 5-volt reference circuit and the APP sensor 1 low reference circuit. Does the test lamp illuminate? | -- | Go to Step 11 | Go to Step 17 |
11 |
Does the scan tool indicate voltage at the specified value? | 5 V | Go to Step 18 | Go to Step 12 |
12 |
Did you find and correct the condition? | -- | Go to Step 22 | Go to Step 20 |
13 |
Did you find and correct the condition? | -- | Go to Step 22 | Go to Step 20 |
14 |
Did you find and correct the condition? | -- | Go to Step 22 | Go to Step 20 |
15 |
Did you find and correct the condition? | -- | Go to Step 22 | Go to Step 20 |
16 |
Did you find and correct the condition? | -- | Go to Step 22 | Go to Step 20 |
17 |
Did you find and correct the condition? | -- | Go to Step 22 | Go to Step 20 |
18 | Inspect for poor connections at the harness connector of the APP sensor. 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 22 | Go to Step 19 |
19 | Replace the APP sensor assembly. Did you complete the replacement? | -- | Go to Step 22 | -- |
20 | Inspect for poor connections at the harness connector of the ECM. 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 22 | Go to Step 21 |
21 | Replace the ECM. Refer to Engine Control Module Replacement/Restore Fuel Rate Data . Did you complete the replacement? | -- | Go to Step 22 | -- |
22 |
Does the DTC run and pass? | -- | Go to Step 23 | Go to Step 2 |
23 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | |
DTC P1271 With RPO CTF
| Table 1: | APP Sensor Position Table |
Circuit Description
The accelerator pedal position (APP) sensor is mounted on the accelerator pedal assembly. The sensor is made up of 3 individual sensors within one housing.
The accelerator pedal position sensor 1, sensor 2, and sensor 3 are potentiometer type sensors, each with the following circuits:
| • | A 5-volt reference circuit |
| • | A low reference circuit |
| • | A signal circuit |
The engine control module (ECM) provides the APP sensors a 5-volt reference circuit and a low reference circuit. The APP sensors then provide the ECM signal voltages proportional to pedal movement. The APP sensor 1 signal voltage is low at rest and increases as the pedal is depressed. The APP sensor 2 signal voltage is high at rest and decreases as the pedal is depressed. The APP sensor 3 signal voltage is high at rest and decreases as the pedal is depressed.
When the ECM detects that the APP sensor 1 signal and the APP sensor 2 signal circuits are out of the correlation, DTC will set.
Conditions for Running the DTC
The ignition is ON.
Conditions for Setting the DTC
The APP sensor 1 and APP sensor 2 are more than 10 percent out of range of each other.
Action Taken When the DTC Sets
| • | The ECM illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails. |
| • | The ECM records the operating conditions at the time the diagnostic fails. The ECM stores this information in the Failure Records. |
| • | If all 3 APP sensors are out of range, the APP indicated angle is limited to 0 percent. The ECM only allows the engine to idle. |
Conditions for Clearing the DTC
| • | A current DTC, Last Test Failed, clears when the diagnostic runs and passes. |
| • | Clear the MIL and the DTC with a scan tool. |
APP Sensor | Actual Pedal Position | % Depressed as Observed on a Scan Tool | Voltage as Observed on a Scan Tool |
|---|---|---|---|
1 | Pedal at rest | 0 | 0.52-0.80 |
1 | Pedal at full travel | 100 | 2.38-2.66 |
2 | Pedal at rest | 0 | 4.20-4.48 |
2 | Pedal at full travel | 100 | 2.34-2.62 |
3 | Pedal at rest | 0 | 3.92-4.09 |
3 | Pedal at full travel | 100 | 2.79-2.96 |
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 |
Does the DTC fail this ignition? | -- | Go to Step 4 | Go to Step 3 |
3 |
Does the DTC fail this ignition? | -- | Go to Step 4 | Go to Intermittent Conditions |
4 | Is DTC P0641, P0651, P1646, P1287 or P1288 also set? | -- | Go to Step 5 | |
5 | Is DTC P1272 also set? | -- | Go to Step 7 | Go to Step 6 |
6 | Is DTC P1273 also set? | -- | Go to Step 10 | -- |
7 |
Does the test lamp illuminate? | -- | Go to Step 8 | Go to Step 14 |
8 | With a test lamp connected to ground, test for voltage at the APP sensor 2 signal circuit. Does the test lamp illuminate? | -- | Go to Step 9 | Go to Step 15 |
9 | Connect a test lamp between the APP sensor 2, 5-volt reference circuit and the APP sensor 2 low reference circuit. Does the test lamp illuminate? | -- | Go to Step 19 | Go to Step 16 |
10 |
Does the test lamp illuminate? | -- | Go to Step 11 | Go to Step 17 |
11 | Connect the test lamp between the APP sensor 1, 5-volt reference circuit and the APP sensor 1 low reference circuit. Does the test lamp illuminate? | -- | Go to Step 12 | Go to Step 18 |
12 |
Does the scan tool indicate voltage at the specified value? | 5 V | Go to Step 19 | Go to Step 13 |
13 |
Did you find and correct the condition? | -- | Go to Step 23 | Go to Step 21 |
14 |
Did you find and correct the condition? | -- | Go to Step 23 | Go to Step 21 |
15 |
Did you find and correct the condition? | -- | Go to Step 23 | Go to Step 21 |
16 |
Did you find and correct the condition? | -- | Go to Step 23 | Go to Step 21 |
17 |
Did you find and correct the condition? | -- | Go to Step 23 | Go to Step 21 |
18 |
Did you find and correct the condition? | -- | Go to Step 23 | Go to Step 21 |
19 | Inspect for poor connections at the harness connector of the APP sensor. Did you find and correct the condition? | -- | Go to Step 23 | Go to Step 20 |
20 | Replace the APP sensor assembly. Refer to Accelerator Pedal Position Sensor Replacement . Did you complete the replacement? | -- | Go to Step 23 | -- |
21 | Inspect for poor connections at the harness connector of the ECM. Did you find and correct the condition? | -- | Go to Step 23 | Go to Step 22 |
22 |
Important: The replacement ECM must be programmed. Replace the ECM. Refer to Engine Control Module Replacement/Restore Fuel Rate Data . Did you complete the replacement? | -- | Go to Step 23 | -- |
23 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 24 |
24 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |
