Circuit Description
The accelerator pedal position (APP) sensor is mounted on the accelerator pedal control assembly. The sensor is made up of 2 individual sensors within one housing. Two 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. 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 a fault with the APP sensor.
Conditions for Setting the DTC
| • | The APP 1 or 2 voltage is more than 4.8 volts for 1 second. |
| OR |
| • | The APP 1 or 2 voltage is less than 0.5 volts for 1 second. |
| OR |
| • | The difference between APP 1 and APP 2 is more than 0.2 volts. |
| AND |
| The voltage at intermediate throttle for APP 1 or 2 is within 0.05 volts of idle voltage. |
Action Taken When the DTC Sets
| • | The ECM will illuminate the malfunction indicator lamp (MIL) the first time the fault is detected. |
| • | When one sensor is normal, backup by normal sensor. |
| • | When both sensors are faulty, the APP is fixed at 20 percent. |
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. |
DTC 0024 can be cleared by using the Clear Info on the scan tool or by using the Diag Clear Switch.
Diagnostic Aids
Inspect for the following conditions:
| • | Poor connection at the ECM |
| Inspect the harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal-to-wire connection. |
| • | Damaged harness |
| Inspect the wiring harness for damage, shorts to ground, shorts to battery, and open circuits. If the harness appears to be OK, observe the APP sensor display on the scan tool while moving connectors and wiring harnesses related to the APP sensor. A change in the APP sensor scan tool display will indicate the location of the fault. |
| • | Poor acceleration |
| • | No accelerator response |
| • | 1,200 RPM fixed |
Step | Action | Value | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||||||||||
1 | Does DTC 0024 set while the ignition is ON or the engine is running? | -- | Go to Step 2 | Go to Diagnostic Aids | ||||||||
2 | Measure the voltage between the following points:
Does the voltage measure outside of the specified range? | At idle 0.95-1.05 V at WOT 4.5 V (Max) | Go to Step 3 | Go to Step 4 | ||||||||
3 |
Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 15 | ||||||||
4 | Measure the voltage between pin number 41 and pin number 42 at the ECM connector C2. Does the voltage measure less than the specified value? | 0.2 V | Go to Step 6 | Go to Step 5 | ||||||||
5 | Does the APP sensor voltage change when the accelerator pedal is depressed? | -- | System OK | Go to Step 13 | ||||||||
6 | Measure the voltage between pin number 41 and pin number 42 at the ECM when the accelerator pedal is operated from idle to wide open throttle (WOT). Does the voltage measure less than the specified value? | 0.2 V | Go to Step 7 | Go to Step 17 | ||||||||
7 |
Does the voltage measure within the specified range? | 4-6 V | Go to Step 11 | Go to Step 8 | ||||||||
8 |
Does the resistance measure less than the specified value? | 2 ohms | Go to Step 9 | Go to Step 18 | ||||||||
9 | Measure resistance of the following points on the APP sensor harness:
Does the resistance measure more than the specified value? | 10 M ohms | Go to Step 10 | Go to Step 18 | ||||||||
10 |
Do both voltages measure within the specified range? | 4-6 V | Go to Step 20 | Go to Step 19 | ||||||||
11 |
Does the resistance measure less than the specified value? | 2 ohms | Go to Step 12 | Go to Step 18 | ||||||||
12 | Measure resistance at the following points:
Do both resistances measure more than the specified value? | 10 M ohms | Go to Step 16 | Go to Step 18 | ||||||||
13 | Readjust the APP sensor. Did you find and correct the condition? | -- | Go to Step 21 | Go to Step 16 | ||||||||
14 | Clear all DTCs. Does DTC 0024 reset? | -- | Go to Step 19 | System OK | ||||||||
15 | Repair/readjust the wiring harness or APP sensor. Did you complete the action? | -- | Go to Step 21 | -- | ||||||||
16 |
Does DTC 0024 reset? | -- | Go to Step 20 | System OK | ||||||||
17 | Repair the APP sensor wiring harness connecting condition or replace the APP sensor. Did you complete the action? | -- | Go to Step 21 | -- | ||||||||
18 | Repair/replace the APP sensor wiring harness. Did you complete the action? | -- | Go to Step 21 | -- | ||||||||
19 | Replace the ECM. Refer to Engine Control Module Replacement/Restore Fuel Rate Data . Did you complete the replacement? | -- | Go to Step 21 | -- | ||||||||
20 |
Important: After replacing the APP, adjust the voltage at idle position. Replace the APP sensor. Did you complete the replacement? | -- | Go to Step 21 | Go to Step 14 | ||||||||
21 | Clear the DTCs. Does DTC 0024 reset? | -- | Go to Step 2 | System OK | ||||||||
