Circuit Description
The powertrain control module (PCM) uses the fuel level input in order to calculate the expected vapor pressures within the fuel system. These vapor pressures vary as the fuel level changes. The vapor pressure is critical in determining if the Evaporative Emissions system is operating properly. The PCM also uses the fuel level in order to determine if the fuel level is too high or too low to be able to accurately detect EVAP system malfunction.
Conditions for Setting the DTC
The fuel level has not changed more than 1.6% (4 counts) in 120 miles.
Action Taken When the DTC Sets
| • | The PCM records the operating conditions at the time the diagnostic fails. The Failure Records buffers will store this information. |
| • | A History DTC is stored. |
| • | The fuel tank level defaults to 40 percent. |
Conditions for Clearing the DTC
| • | A History DTC clears after 40 consecutive warm up cycles without a fault. |
| • | Use a scan tool to clear the DTCs. |
Diagnostic Aids
| • | An intermittent problem may be caused by the following conditions: |
| - | Poor electrical connection |
| - | Rubbed through wire insulation |
| - | A wire that is broken inside the wire insulation |
| • | Any circuitry, that is suspected as causing the intermittent complaint, should be thoroughly checked for the following conditions: |
| - | Backed out terminals |
| - | Improper mating |
| - | Broken locks |
| - | Improperly formed or damaged terminals |
| - | Poor terminal to wire connection |
Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table.
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The Powertrain OBD System Check prompts the technician to complete some basic checks and store the Freeze Frame Data and the Failure records on the scan tool if applicable. This creates an electronic copy of the data taken when the malfunction occurred. This information on the scan tool can be referred to later.
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Before replacing the PCM, check terminals for improper mating, broken locks, or physical damage to the wiring harness. Replacement PCMs must be reprogrammed and the crankshaft position system variation procedure must be performed. Refer to the latest Isuzu Technical Communication System (ITCS) information for programming procedures and also refer to the Crankshaft Position System Variation Learn .
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | |||
2 |
Are DTC P0462 or P0463 set? | -- | Go to DTC P0462 Fuel Level Sensor Circuit Low Voltage or | |
3 |
Does scan tool indicate specified level? | 100% | ||
4 | Jumper the Fuel Level Sensor ground circuit to the Fuel Level Sensor signal circuit. The scan tool should read specified value. Does the scan tool display specified value? | 0% | ||
5 | Check the Fuel Level sensor signal circuit for a short to ground. Repair if malfunction was found. Was a malfunction found? | -- | ||
6 | Connect a test light to B+ and probe the Fuel Level sensor ground circuit. The test light should illuminate. Does the test light illuminate? | -- | ||
7 | Check for an open or malfunctioning connections on the Fuel Level sensor signal circuit and repair if malfunction was found. Was a malfunction found? | -- | ||
8 | Check for an open or malfunctioning ground circuit electrical connection at the PCM and repair if malfunction was found. Was a malfunction found? | |||
Replace the PCM. Refer to Powertrain Control Module Replacement . Is the action complete? | -- | -- | ||
10 | Check for an open or malfunctioning connections at the Fuel Level Sensor and repair if malfunction was found. Was a malfunction found? | -- | ||
11 | Replace the Fuel Level Sensor. Refer to Fuel Level Sensor Replacement . Is the action complete? | -- | -- | |
12 |
Does the scan tool indicate that this diagnostic ran and passed? | -- | ||
13 | Check if any additional DTCs are set. Are any DTCs displayed that have not been diagnosed? | -- | Go to Applicable DTC Table | System OK |
