Circuit Description
The throttle position (TP) sensor provides a voltage signal that changes relative to the throttle opening. The TP sensor signal voltage varies from about 0.35 volt at idle to over 4.65 volts at wide open throttle (WOT).
The TP sensor signal is used by the ECU for fuel trim and diagnostic functions.
The ECU monitors the MAP and RPM and determines if the TP angle is within a predetermined operational window. If the TP sensor falls outside this window, DTC 26 will be set.
This is a type B DTC.
Conditions for Setting the DTC
The following conditions will set the DTC:
| • | The vehicle is in the CNG operation mode. |
| • | The engine is running. |
| • | The manifold pressure is less than 45 kPa. |
| • | None of the following DTCs are active: 14, 15, 16, 21, 22, 23, 25, 32, 33, 34, 41, 42, 44, 45, 51, 52, 53, 55, 56 or 58, AND |
| • | The TP angle is greater than the following specified percentages at the given RPM for at least two seconds: |
| - | TP angle is greater than 30% at 500 RPM |
| - | TP angle is greater than 40% at 1500 RPM |
| - | TP angle is greater than 50% at 2000 RPM |
| - | TP angle is greater than 60% at 3000 RPM |
| - | TP angle is greater than 70% at 3500 RPM |
| - | TP angle is greater than 80% at 4000 RPM |
| - | TP angle is greater than 90% at 4600 RPM |
Action Taken When the DTC Sets
The ECU sets DTC 26 after two consecutive ignition cycles with the fault active.
Conditions for Clearing the MIL/DTC
The ECU turns the MIL OFF after three consecutive driving trips without a fault condition present. A DTC will clear if no fault conditions have been detected for 40 warm-up cycles (coolant temperature has risen 72°F (40°C) from the start-up coolant temperature and the engine coolant temperature exceeds 160°F (70°C) during that same ignition cycle) or the code clearing procedure has been used.
Diagnostic Aids
Always diagnose ANY PCM codes that are present before beginning this diagnostic procedure.
A scan tool displays the throttle position in volts. It should display 0.20 volt to 0.90 volt with the throttle closed and the ignition ON or the engine idling. The voltage should increase at a steady rate as the throttle is moved toward Wide Open Throttle (WOT). Also, the scan tool displays the throttle angle percentage where 0% = closed and 100% = WOT.
A TP sensor that is stuck will attempt an auto zero every time that the engine runs. The TP sensor will not display as high a percentage when the sensor has auto zeroed at a higher than normal voltage.
A normal TP sensor that displays 0 percent will not display higher than 1 volt and is possibly stuck. Inspect the condition of the connector and the sensor terminals for moisture or corrosion. Clean or replace the connector or the terminals as necessary. If corrosion is found, inspect the condition of the connector seal. Repair or replace the seal as necessary.
If the DTC is intermittent, refer to Intermittent Conditions .
Test Description
The number(s) below refer to the step number(s) on the diagnostic table.
-
The TP sensor has an auto zeroing feature. If the voltage reading is within the range of about 0.2 to 0.9 volt, the ECU/PCM uses that value as a closed throttle. If the reading is out of the auto zero range at closed throttle, inspect for a binding throttle or a damaged linkage. If the throttle and the linkage are OK, continue with the diagnosis.
-
With the TP sensor disconnected, the TP sensor voltage should go low if the ECU/PCM and the wiring are OK.
-
An inaccurate or sticking MAP sensor may cause a DTC 26 to set and should be inspected carefully.
-
By disconnecting connector C018, this isolates the ECU and the wiring from the PCM. This will help to determine where the fault may exist.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the AF Powertrain OBD System Check performed? | -- | Go to Step 2 | Go to Alternative Fuels (AF) Powertrain On Board (OBD) System Check |
Does the TP angle value increase steadily to greater than the first specified value and does the TP angle value decrease steadily to less than the second specified value? | 98% 1% | Go to Step 3 | Go to Step 4 | |
3 |
The fuel indicator light will remain OFF due to the removal of the CNG system fuse. Did DTC P0121 run and pass? | -- | Go to Step 7 | Go to DTC P0121 TP Sensor Performance in Engine Controls - 2.2L in the J Platform Service Manual |
4 | Does the scan tool display a TP voltage below the specified value with the throttle closed? | 0.80 V | Go to Step 6 | Go to Step 5 |
Does the scan tool display the TP sensor voltage less than the specified value? | 0.5 V | Go to Step 12 | Go to Step 15 | |
6 | Probe the 5 volt reference circuit at the TP sensor connector with a DVOM connected to ground. Does the DVOM display a voltage near the specified value? | 5.0 V | Go to Step 11 | Go to Step 10 |
7 |
Is there continuity? | -- | Go to Step 8 | Go to Step 13 |
Was a problem found? | -- | Go to Step 13 | Go to Step 9 | |
9 | The DTC is intermittent. If no additional DTCs are set, refer to Diagnostic Aids. If additional DTCs are set, refer to those tables. Are any additional DTCs set? | -- | Go to the applicable DTC table | Go to Diagnostic Aids |
10 | Inspect the TP sensor 5 volt reference circuit for a short to ground or a short to voltage. Was a problem found? | -- | Go to Step 13 | Go to Step 19 |
11 |
Was a problem found? | 0.4 ohms | Go to Step 13 | Go to Step 12 |
12 | Inspect for faulty connections at the TP sensor. Was a problem found? | -- | Go to Step 13 | Go to Step 14 |
13 | Repair the circuit as necessary. Refer to Wiring Repairs in Engine Controls - 2.2L in the J Platform Service Manual. Is the repair complete? | -- | Go to Step 20 | -- |
14 | Replace the TP sensor. Refer to TP Sensor Replacement in Engine Controls - 2.2L in the J Platform Service Manual. Is the replacement complete? | -- | Go to Step 20 | -- |
Does the scan tool display the TP sensor voltage less than the specified value? | 0.5 V | Go to Step 16 | Go to Step 18 | |
16 |
Was a repair made? | -- | Go to Step 20 | Go to Step 17 |
17 | Replace the ECU. Refer to Engine Control Unit Replacement . Is the action complete? | -- | Go to Step 20 | -- |
18 |
Was a repair made? | -- | Go to Step 20 | Go to Step 19 |
19 |
Important: If the PCM is faulty, reprogram the PCM. Refer to PCM Replacement/Programming in Engine Controls - 2.2L in the J Platform Service Manual. Is the action complete? | -- | Go to Step 20 | -- |
20 |
Did the diagnostic run and pass? | -- | Go to Step 21 | Go to Step 2 |
21 | Are any DTCs displayed that have not been diagnosed? | -- | Go to the applicable DTC table | System OK |
