PACCAR MX (2004 Emissions) Fault Code: P1678 PCI ECU – Software Error
SET CONDITIONS:
Programmed data in the ECU not correct.
DIAGNOSTIC CONDITION:
This diagnostic runs during start-up of the PCI ECU.
RESET CONDITION:
This DTC changes to inactive when the fault is no longer detected.
POSSIBLE CAUSES:
Software fault
ADDITIONAL INFORMATION:
1. The PCI ECU does not start up.
2. Engine cannot be started.
PACCAR MX (2004 Emissions) Fault Code: P1679 PCI ECU – Internal Error
SET CONDITIONS:
Programmed data in the ECU not correct.
DIAGNOSTIC CONDITION:
This diagnostic runs during start-up of the PCI ECU.
RESET CONDITION:
This DTC changes to inactive when the fault is no longer detected.
POSSIBLE CAUSES:
Software fault
ADDITIONAL INFORMATION:
1. The PCI ECU does not start up.
2. Engine cannot be started.
PACCAR MX (2004 Emissions) Fault Code: P1681 PCI ECU – Software Error
SET CONDITIONS:
Programmed data in the ECU not correct.
DIAGNOSTIC CONDITION:
This diagnostic runs during start-up of the PCI ECU.
RESET CONDITION:
This DTC changes to inactive when the fault is no longer detected.
POSSIBLE CAUSES:
Software fault
ADDITIONAL INFORMATION:
1. The PCI ECU does not start up.
2. Engine cannot be started.
PACCAR MX (2004 Emissions) Fault Code: P1682 Engine Oil Level – Current Too Low or Open Circuit on ECU (D420) Pin (B35)
CORRESPONDING OBD READINESS MONITOR:
None
REPAIR VERIFICATION:
1. Clear all DTCs.
2. Test drive or operate the vehicle to meet the diagnostic conditions and set conditions.
3. Did the DTC come back?
– No, repair successful
– Yes, repair unsuccessful
PACCAR MX (2004 Emissions) Fault Code: P1687 Starter Motor – Voltage Too High or Short Circuit to Supply on ECU (D420) Pin (B16)
SET CONDITIONS:
This DTC is set when the ECU detects a higher voltage than expected on the signal or control circuit of the ECU.
DIAGNOSTIC CONDITION:
The diagnostic runs continuously when the ignition is keyed on.
CORRESPONDING OBD READINESS MONITOR:
None
RESET CONDITION:
The DTC changes to inactive after the diagnostic runs and passes.
REPAIR VERIFICATION:
1. Clear all DTCs.
2. Test drive or operate the vehicle to meet the diagnostic conditions and set conditions.
3. Did the DTC come back?
– No, repair successful
– Yes, repair unsuccessful
POSSIBLE CAUSES:
1. The sensor or actuator signal wiring has a short circuit to supply.
2. A malfunction of the sensor or actuator
PACCAR MX (2004 Emissions) Fault Code: P1688 Starter Motor – Voltage Too Low or Short Circuit to Ground on ECU (D420) Pin (B16)
SET CONDITIONS:
This DTC is set when the ECU detects a lower voltage than expected on the signal or control circuit of the ECU.
DIAGNOSTIC CONDITION:
The diagnostic runs continuously when the ignition is keyed on.
CORRESPONDING OBD READINESS MONITOR:
None
RESET CONDITION:
The DTC changes to inactive after the diagnostic runs and passes.
REPAIR VERIFICATION:
1. Clear all DTCs.
2. Test drive or operate the vehicle to meet the diagnostic conditions and set conditions.
3. Did the DTC come back?
– No, repair successful
– Yes, repair unsuccessful
POSSIBLE CAUSES:
1. The sensor or actuator signal wiring is interrupted.
2. The sensor or actuator signal wiring has a short circuit to ground.
3. A malfunction in the power supply of the sensor or actuator
4. A malfunction of the sensor or actuator
ADDITIONAL INFORMATION:
Multiple voltage-too-low sensor-related DTCs may indicate a malfunction within one of the 5-V sensor power supply circuits of the PCI ECU.
PACCAR MX (2004 Emissions) Fault Code: P1693 Cold Starting Aid – Voltage Too High or Short Circuit to Supply on ECU (D420) Pin (C72) or Pin (C49)
SET CONDITIONS:
This DTC is set when the ECU detects a higher voltage than expected on the signal or control circuit of the ECU.
DIAGNOSTIC CONDITION:
The diagnostic runs continuously when the ignition is keyed on.
CORRESPONDING OBD READINESS MONITOR:
None
RESET CONDITION:
The DTC changes to inactive after the diagnostic runs and passes.
REPAIR VERIFICATION:
1. Clear all DTCs.
2. Test drive or operate the vehicle to meet the diagnostic conditions and set conditions.
3. Did the DTC come back?
– No, repair successful
– Yes, repair unsuccessful
POSSIBLE CAUSES:
1. The sensor or actuator signal wiring has a short circuit to supply.
2. A malfunction of the sensor or actuator
PACCAR MX (2004 Emissions) Fault Code: P1694 Cold Starting Aid – Voltage Too Low or Short Circuit to Ground on ECU (D420) Pin (C72) or Pin (C49)
SET CONDITIONS:
This DTC is set when the ECU detects a lower voltage than expected on the signal or control circuit of the ECU.
DIAGNOSTIC CONDITION:
The diagnostic runs continuously when the ignition is keyed on.
CORRESPONDING OBD READINESS MONITOR:
None
RESET CONDITION:
The DTC changes to inactive after the diagnostic runs and passes.
REPAIR VERIFICATION:
1. Clear all DTCs.
2. Test drive or operate the vehicle to meet the diagnostic conditions and set conditions.
3. Did the DTC come back?
– No, repair successful
– Yes, repair unsuccessful
POSSIBLE CAUSES:
1. The sensor or actuator signal wiring is interrupted.
2. The sensor or actuator signal wiring has a short circuit to ground.
3. A malfunction in the power supply of the sensor or actuator
4. A malfunction of the sensor or actuator
ADDITIONAL INFORMATION:
Multiple sensor related voltage-too-low DTCs can indicate a malfunction within a 5-V sensor power supply circuit of the PCI ECU.
PACCAR MX (2004 Emissions) Fault Code: P1698 PCI ECU 5V Sensor Supply – Voltage Too Low or Short Circuit to Ground
SET CONDITIONS:
The PCI ECU (D420) detects that the internal ‘5V power supply 4’ voltage is too low.
DIAGNOSTIC CONDITION:
This diagnostic runs continuously when the ignition is on.
CORRESPONDING OBD READINESS MONITOR:
None
RESET CONDITION:
This DTC changes to inactive when the fault is no longer detected.
REPAIR VERIFICATION:
1. Clear all DTCs.
2. Test drive or operate the vehicle to meet the diagnostic conditions and set conditions.
3. Did the DTC come back?
– No, repair successful
– Yes, repair unsuccessful
POSSIBLE CAUSES:
Defective PCI ECU (D420)
ADDITIONAL INFORMATION:
1. Various 5V engine sensors receive their power supply through one of the 5V power supply groups from the PCI ECU (D420).
2. When this DTC is active, all sensors connected to ‘5V power supply 4’ will be out of operation.
PACCAR MX (2004 Emissions) Fault Code: P1699 PCI ECU 5V Sensor Supply – Voltage Too High or Short Circuit to Supply
SET CONDITIONS:
The PCI ECU (D420) detects that the internal ‘5V power supply 4’ voltage is too high.
DIAGNOSTIC CONDITION:
This diagnostic runs continuously when the ignition is on.
CORRESPONDING OBD READINESS MONITOR:
None
RESET CONDITION:
This DTC changes to inactive when the fault is no longer detected.
REPAIR VERIFICATION:
1. Clear all DTCs.
2. Test drive or operate the vehicle to meet the diagnostic conditions and set conditions.
3. Did the DTC come back?
– No, repair successful
– Yes, repair unsuccessful
POSSIBLE CAUSES:
Defective PCI ECU (D420)
ADDITIONAL INFORMATION:
1. Various 5V engine sensors receive their power supply through one of the 5V power supply groups from the PCI ECU (D420).
2. When this DTC is active, all sensors connected to ‘5V power supply 4’ will be out of operation.