Paccar

PACCAR MX (2004 Emissions) Fault Code: P0666 Internal ECU Temperature – Data Erratic, Intermittent or Incorrect, at Ignition On

SET CONDITIONS:
The PCI ECU (D420) detects that the measured internal ECU temperature differs more than 3?C [5.4?F] from the average of other temperature sensors on the engine for more than 5 seconds (after the ignition has been keyed off for at least 8 hours).

DIAGNOSTIC CONDITION:
This diagnostic runs:
1. When the ignition has been keyed off continuously for at least 8 hours
2. Difference between the coolant temperature and ambient temperature is less than 15?C [27?F]
3. Ambient temperature is more than -20?C [-4?F]

CORRESPONDING OBD READINESS MONITOR:
None

RESET CONDITION:
The 8-hour ignition off diagnostic consists of three separate steps:
1. The vehicle ignition may NOT be keyed on or engine started for 8 to 10 consecutive hours (ideal situation would be overnight).

2. After the 8-10 consecutive hours, key on the ignition (NO engine start) and wait for 10 seconds to allow the system to power-up and the diagnostics to run.

3. Start the engine and let it idle for 2 minutes. 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? (Can be pending, inactive or active)
– No, repair successful
– Yes, repair unsuccessful

POSSIBLE CAUSES:
Faulty temperature sensor, internally in ECU. If the fault recurs, replace the ECU.

ADDITIONAL INFORMATION:
1. The PCI ECU temperature is monitored by an internal temperature sensor in the printed circuit board. This temperature sensor is not serviceable.

2. For this diagnostic, the internal PCI ECU temperature sensor reading is compared with an average of other temperature sensors on the engine after the ignition has been keyed off for at least 8 hours.

PACCAR MX (2004 Emissions) Fault Code: P0668 Internal ECU Temperature – Internal Error

SET CONDITIONS:
The temperature measured by the internal ECU temperature sensor is out of range 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:
Faulty temperature sensor, internally in ECU. Clear the fault with the diagnostic service tool. If the fault reoccurs after ignition on, replace the ECU.

ADDITIONAL INFORMATION:
The PCI ECU temperature is monitored by an internal temperature sensor in the printed circuit board. This temperature sensor is not serviceable.

PACCAR MX (2004 Emissions) Fault Code: P0669 Internal ECU Temperature – Internal Error

SET CONDITIONS:
The temperature measured by the internal ECU temperature sensor is out of range 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:
Faulty temperature sensor, internally in ECU. Clear the fault with the diagnostic service tool. If the fault reoccurs after ignition on, replace the ECU.

ADDITIONAL INFORMATION:
The PCI ECU temperature is monitored by an internal temperature sensor in the printed circuit board. This temperature sensor is not serviceable.

PACCAR MX (2004 Emissions) Fault Code: P0685 PCI ECU – Short Circuit to Ground on ECU (D420) Pin (B3)

SET CONDITIONS:
The PCI ECU (D420) detects a short circuit to ground on pin (B03).

DIAGNOSTIC CONDITION:
This diagnostic runs when the ignition is keyed on and off.

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:
Short circuit to ground in the circuit of ECU pin B3.

ADDITIONAL INFORMATION:
The PCI ECU (D420) activates and deactivates its own main power by energizing relay (3).

When the ignition is:
1. Switched on, power supply is supplied to ECU pin B1. The ECU activates the relay (3) by switching ECU pin B3 to ground, and power supply is available on ECU pins B60/B61/B62.

2. Switched off, power supply is removed from ECU pin B1. The ECU performs different tasks, like storing data, and subsequently deactivates the relay (3) by removing the ground from ECU pin B3. The power supply is then removed from ECU pins B60/B61/B62.

Depending on the OEM electrical system architecture, it is possible that the PCI ECU remains powered on when the ignition is keyed off with this DTC active.

PACCAR MX (2004 Emissions) Fault Code: P0691 Electronically Controlled Fan – Voltage Too Low or Short Circuit to Ground on ECU (D420) Pin (C74)

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: P0692 Electronically Controlled Fan – Voltage Too High or Short Circuit to Supply on ECU (D420) Pin (C74)

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: P0698 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 1’ 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:
Issues within the ‘5V power supply 1’ with:
1. Sensor wiring
2. Sensor malfunction

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 1’ will be out of operation.

PACCAR MX (2004 Emissions) Fault Code: P0699 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 1’ 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:
Issues within the ‘5V power supply 1’ with:
1. Sensor wiring
2. Sensor malfunction

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 1’ will be out of operation.

PACCAR MX (2004 Emissions) Fault Code: P06AD Internal ECU Temperature – Internal Error

SET CONDITIONS:
The injector driver temperature measured by the internal ECU temperature sensor is out of range 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:
1. Faulty temperature sensor, internally in ECU.
2. Clear the fault with the diagnostic service tool. If the fault reoccurs after ignition on, replace the ECU.

ADDITIONAL INFORMATION:
The PCI ECU injector driver temperature is monitored by an internal temperature sensor on the printed circuit board. This temperature sensor is not serviceable.