Circuit Description
The PCM supplies a 5V reference and a ground to the sensor. The TP sensor sends a voltage signal back to the PCM relative to throttle blade opening. The TP sensor signal voltage will vary from 0.2 V at closed throttle to over 4.5 V at wide open throttle. The TP sensor is one the most important sensor in the control of fuel delivery.
Conditions for Setting the DTC
| • | Engine is running. |
| • | TP sensor voltage is greater than 3.9 V for 5 seconds. |
| • | MAP is less than 60 kPa. |
| Engine speed is less than 1500 RPM. |
| • | DTCs P0107 or P0108 not set. |
| OR |
| • | TP sensor voltage is greater than 4.8V. |
| • | DTCs P0107 or P0108 not set. |
Action Taken When the DTC Sets
| • | The Malfunction Indicator Lamp (MIL) illuminates. |
| • | The PCM records the operating conditions at the time the diagnostic fails. This information will be stored in The Freeze Frame and Failure Records buffers stores this information. |
| • | A history DTC is stored. |
| • | The TP angle will default to 0% when the vehicle speed is less than 2 mph. The TP angle defaults to 10% when the vehicle speed is greater than 2 mph. The scan tool shows the defaulted value. |
Conditions for Clearing the MIL/DTC
| • | The malfunction indicator lamp (MIL) will turn OFF after 3 consecutive ignition cycles in which the diagnostic runs without a fault. |
| • | A history DTC will clear after 40 consecutive warm up cycles without a fault. |
| • | Use a scan tool to clear the DTCs. |
Diagnostic Aids
| • | With the ignition ON and the throttle at closed position, the voltage should read between 0.20 V and 0.90 V and increase steadily to over 4.5 V at wide open throttle. |
| • | Check the connectors for proper mating. Replace as necessary. Repair as necessary. |
Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table.
-
The Powertrain OBD System Check prompts the technician to complete some basic checks and store the freeze frame and failure records data on the scan tool if applicable. This creates an electronic copy of the data taken when the malfunction occurred. The information is then stored in the scan tool for later reference.
-
With the throttle closed, the TP sensor voltage should read less than 0.90V. If the TP sensor voltage does not read less than 0.90V check for a binding or sticking throttle cable.
-
With the TP sensor electrical terminal disconnected, the TP sensor voltage should less than 0.2 volts if the PCM and wiring are OK.
-
Probing the ground circuit with a test light checks the circuit for high resistance which will cause a DTC P0123 to set.
-
A shorted 5.0 volt reference circuit will also set additional DTCs.
-
Replacement PCMs must be reprogrammed and the crankshaft position system variation procedure must be preformed. Refer to the latest Isuzu Technical Communication System (ITCS) information for programming procedures and also refer to the Powertrain Control Module (PCM) .
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | Go to | ||
Is the TP sensor voltage greater than the specified value? | 1.0V | |||
3 |
Is the TP sensor voltage greater than the specified value? | 3.9V | ||
Disconnect the TP sensor electrical connector. Is the TP sensor voltage less than the specified value? | 0.2V | |||
Connect a test light to B+ and probe the TP sensor ground circuit at the TP sensor harness connector. Does the test light illuminate? | -- | |||
6 | Check the TP sensor signal circuit for a short to voltage and repair as necessary. Was a repair necessary? | -- | ||
Check the TP sensor 5 volt reference circuit for a short to B+ and repair as necessary. Was a repair necessary? | -- | |||
8 | Check the TP sensor electrical connector for poor connection and replace the terminals as necessary. Was a repair necessary? | -- | ||
9 | Check the TP sensor ground circuit for a open and repair as necessary. Was a repair necessary? | -- | ||
10 | Replace the TP sensor. Refer to Throttle Position Sensor Replacement . Is the action complete? | -- | -- | |
Check for poor connections at the PCM . If connections are OK, replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Is the action complete? | -- | -- | ||
12 |
Does the scan tool indicate that the diagnostic ran and passed? | -- | ||
13 | Check if any additional DTCs are set. Are any additional DTCs displayed that have not been diagnosed? | -- | Go to applicable DTC table | System OK |
