Paccar

PACCAR MX (2004 Emissions) Fault Code: P1062 Cruise Control Switches – Data Erratic, Intermittent, or Incorrect

SET CONDITIONS:
The PCI ECU (D420) detects that both the cruise control set(+) switch and the res(-) switch are active at the same time.

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:
Mechanical failure or damage to the cruise control switches

PACCAR MX (2004 Emissions) Fault Code: P1086 Common Rail Fuel Pressure – Increase Too Slow

SET CONDITIONS:
The PCI ECU (D420) detects that the actual rail pressure is below 150 bar [2176 psi] for more than 5 seconds.

DIAGNOSTIC CONDITION:
This diagnostic runs when the rail pressure operating state is: Filling rail (during starting).

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:
A leaking injector sealing ring.

This DTC is mostly the result of a fuel system-related issue for which another fuel system-related DTC is stored Troubleshoot these DTCs first

If no fuel system related DTCs are present:
1. Air present in the fuel system. If the fuel system or parts of it have been emptied during maintenance or repair, this DTC may become active temporarily after the engine is started. If the DTC stays inactive when the engine is running, no further investigation is necessary.
2. Fuel gelling at very low ambient temperatures.
3. An external or internal leakage on the high-pressure fuel system components

ADDITIONAL INFORMATION:
1. The rail pressure is closed-loop controlled. A comparison is made between the requested and actual rail pressure measured by the common rail pressure sensor.

2. The actual rail pressure is measured in the common rail by the common rail pressure sensor (F854)

3. P1086 only indicates that the rail pressure is insufficient during cranking. It is mostly the result of a fuel system related issue for which another fuel system-related DTC is stored. Therefore always check if another fuel-system related DTC was stored on the diagnostic service tool session report just before P1086 was stored. The driver’s complaint and malfunction point of time can help indicate a related DTC. Start investigating these DTCs first.

PACCAR MX (2004 Emissions) Fault Code: P1087 Fuel Pressure – Data Valid but Too Low, Moderately Severe

SET CONDITIONS:
The PCI ECU (D420) detects that the fuel pressure is too low for more than 50 seconds.

DIAGNOSTIC CONDITION:
This diagnostic runs when the engine has been running for more than 200 seconds.

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 fuel pressure control valve Restriction in the fuel supply or low performance of the fuel lift pump.

ADDITIONAL INFORMATION:
The low pressure fuel pressure is measured by the fuel pressure sensor (F801).

PACCAR MX (2004 Emissions) Fault Code: P1088 Common Rail Fuel Pressure – Data Valid but Too High

SET CONDITIONS:
The PCI ECU (D420) detects that the measured rail pressure is more than 2840 bar [41191 psi].

DIAGNOSTIC CONDITION:
This diagnostic runs when the rail pressure operating state is: Release valve only.

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:
Common rail pressure release valve failure (stuck in the closed position)

ADDITIONAL INFORMATION:
1. This DTC becomes active in combination with other fuel system related DTCs. Troubleshoot these faults first.

2. The rail pressure is measured in the common rail by the common rail pressure sensor (F854).

3. When this DTC is active:
– The engine torque is reduced.
– The engine runs in engine mode: Protection.
– The engine runs in rail pressure control state: Release valve only.
– The maximum rail pressure is limited to 1300 bar.

PACCAR MX (2004 Emissions) Fault Code: P1089 Common Rail Fuel Pressure – Data Valid but Too High

SET CONDITIONS:
The PCI ECU (D420) detects that the measured rail pressure is more than 2840 bar [41191 psi].

DIAGNOSTIC CONDITION:
This diagnostic runs when the rail pressure operating state is: Pump unit only or Rail discharge.

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 common rail pump unit

ADDITIONAL INFORMATION:
1. The rail pressure is measured in the common rail by the common rail pressure sensor (F854).

2. When this DTC is active:
– The engine torque is reduced.
– The engine runs in protection mode.
– The engine runs in rail pressure control state: Release valve only.
– The maximum rail pressure is limited to 1300 bar.

PACCAR MX (2004 Emissions) Fault Code: P1090 Common Rail Fuel Pressure – Data Valid but Too High

SET CONDITIONS:
The PCI ECU (D420) detects that the measured rail pressure is more than 2840 bar [41191 psi].

DIAGNOSTIC CONDITION:
This diagnostic runs when the rail pressure operating state is: Filling rail or Dumping.

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 common rail pressure sensor

ADDITIONAL INFORMATION:
1. The rail pressure is measured in the common rail by the common rail pressure sensor (F854).

2. When this DTC is active:
– The engine torque is reduced.
– The engine runs in protection mode.
– The engine runs in rail pressure control state: Release valve only.
– The maximum rail pressure is limited to 1300 bar.

PACCAR MX (2004 Emissions) Fault Code: P1091 Common Rail Fuel Pressure – Data Erratic, Intermittent or Incorrect

SET CONDITIONS:
The PCI ECU (D420) detects that the controlled common rail pressure release valve current differs too much from the learned current during an autonomous test.

DIAGNOSTIC CONDITION:
This diagnostic runs every 30 minutes of engine operation when the following conditions are met for longer than 5 seconds:
1. The engine has been running for more than 30 minutes and
2. During a fuel injection cutoff event and
3. Engine speed is between 1200 and 1600 rpm

IMPORTANT: If the autonomous test passes it is repeated every 30 minutes. If the test fails it is repeated every 5 minutes. If the test fails 3 times subsequently this DTC becomes active.

CORRESPONDING OBD READINESS MONITOR:
Fuel system monitor

RESET CONDITION:
This DTC changes to inactive after the ignition is keyed off for at least 15 seconds and keyed on again.

REPAIR VERIFICATION:
1. Clear all DTCs.
2. Test drive or operate the vehicle to meet the following conditions:
– Corresponding readiness monitor displays ‘Ready’
– Diagnostic conditions are met
– Set conditions are met
3. Did the DTC come back?
– No, repair successful
– Yes, repair unsuccessful

POSSIBLE CAUSES:
1. Common rail pressure release valve leakage

2. Only if a new or different common rail pressure release valve has been installed recently: the “Reset common rail pressure release valve” procedure with the diagnostic service tool was not performed. Investigate whether the reset was performed in the past before performing it again. Resetting the common rail pressure release valve without further investigation of the DTC can lead to recurrence of the DTC.

ADDITIONAL INFORMATION:
1. For this diagnostic the common rail pressure sensor (F854) is checked via an autonomous test. During this test, the rail pressure operating state is: RELEASE VALVE ONLY. The rail pressure is controlled by the common rail pressure release valve (L094) during a fuel cutoff event. The PCI ECU controls the common rail pressure release valve with the learned current to reach a rail pressure of 1500 bar. This is compared with the common rail pressure sensor reading.

2. The current to control the common rail pressure release valve (L094) is learned in the PCI ECU memory. This learned current is determined shortly after the vehicle has left the factory or when the common rail pressure release valve is reset by the diagnostic service tool. During the learning process the diagnostics for the DTC is disabled. The status of learning process and the current cannot be read with the diagnostic service tool.

3. It is possible that the engine does not run anymore when this DTC is active.

4. When this DTC is active:
– The engine torque is reduced.
– The engine runs in protection mode.
– The maximum rail pressure is limited to 1300 bar.

PACCAR MX (2004 Emissions) Fault Code: P109C Common Rail Pressure Release Valve – Current Too Low or Open Circuit on ECU (D420) Pin (C4)

POSSIBLE CAUSES:
No repairs are necessary.

ADDITIONAL INFORMATION:
Do not troubleshoot this DTC.

PACCAR MX (2004 Emissions) Fault Code: P109D Common Rail Pressure Release Valve – Current Too High on ECU (D420) Pin (C4)

DIAGNOSTIC CONDITION:
This diagnostic runs continuously when the ignition is on.

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

ADDITIONAL INFORMATION:
When this DTC is active:
1. The engine torque is reduced.
2. The engine runs in protection mode.
3. The rail pressure control is in the limp-home function.
4. The rail pressure is limited to approximately 800 bar.