Paccar

PACCAR MX (2004 Emissions) Fault Code: U1857 Humidity Sensor Software Verification – Incorrect

SET CONDITIONS:
The PCI ECU detects that no or an incorrect calibration verification number (CVN) is received from the humidity sensor.

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

CORRESPONDING OBD READINESS MONITOR:
None

RESET CONDITION:
This DTC changes to inactive after the ignition is keyed off for at least 15 seconds and keyed on again, and 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:
1. No or intermittent CAN communication with the humidity sensor. Check:
– Humidity sensor power supply
– E-CAN communication
2. Incorrect type of humidity sensor installed
3. Faulty humidity sensor

ADDITIONAL INFORMATION:
When the ignition is keyed on, the PCI ECU (D420) queries the humidity sensor (F852) for a calibration verification number (CVN).

CVN is the calibration verification number and is the result of a check performed on the software values stored in emission-related ECUs (OBD legislation).

PACCAR MX (2004 Emissions) Fault Code: U1858 A Fault Exists With the DECECU 11 CVN Calculation

SET CONDITIONS:
This DTC is set when a CAN message is received correctly, but the content (signal value or status) is not available.

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

RESET CONDITION:
The DTC changes to inactive after the diagnostic runs and passes.

POSSIBLE CAUSES:
A malfunction in the system from which the message originates.

PACCAR MX (2004 Emissions) Fault Code: U185A CAN – Message (A1DEFI) Time-Out from Aftertreatment System

SET CONDITIONS:
This DTC is set when the repetition rate of the received CAN message is lower than expected or when the message is not received at all.

DIAGNOSTIC CONDITION:
The diagnostic runs continuously when the ignition is keyed on or when the engine is running.

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. Wiring issues (interruption or contact resistance)
2. Defective components
3. Incorrect software configuration

PACCAR MX (2004 Emissions) Fault Code: U185C CAN Communication – Message (A1DEFI) Out of Range, DEF Property from Aftertreatment System

SET CONDITIONS:
This DTC is set when a CAN message is received correctly, but the content (signal value or status) is out of the expected range.

DIAGNOSTIC CONDITION:
The diagnostic runs continuously when the ignition is keyed on or when the engine is running.

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. A corrupt or empty CAN message
2. A malfunction in the system from which the message originates

ADDITIONAL INFORMATION:
1. A ‘message out of range’ DTC is activated by the receiving ECU but indicates a malfunction within another system which communicates with this ECU.
2. The cause of the DTC must be sought in the system from which it originates.

Example:
1. [ECU 1] detects an incorrect or missing signal from [sensor A].
2. [ECU 1] sets [DTC 1] (In this specific case, an open circuit DTC).
3. [ECU 1] constantly informs [ECU 2] about the status of [sensor A] via CAN messages.
4. Since the data received from the sensor is not available or not plausible, an ’empty’ CAN message is sent from [ECU 1] to [ECU 2].
5. [ECU 2] interprets the empty message as being out of the expected range and sets the ‘out of range DTC’ [DTC 2].

PACCAR MX (2004 Emissions) Fault Code: U185E CAN – Message (EPSI) Time-Out from Aftertreatment System

SET CONDITIONS:
This DTC is set when the repetition rate of the received CAN message is lower than expected or when the message is not received at all.

DIAGNOSTIC CONDITION:
The diagnostic runs continuously when the ignition is keyed on or when the engine is running.

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. Wiring issues (interruption or contact resistance)
2. Defective components
3. Incorrect software configuration

PACCAR MX (2004 Emissions) Fault Code: U185F CAN Communication – Message (EPSI) Out of Range, PM Sensor from Aftertreatment System

SET CONDITIONS:
This DTC is set when a CAN message is received correctly, but the content (signal value or status) is out of the expected range.

DIAGNOSTIC CONDITION:
The diagnostic runs continuously when the ignition is keyed on or when the engine is running.

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. A corrupt or empty CAN message
2. A malfunction in the system from which the message originates

ADDITIONAL INFORMATION:
1. A ‘message out of range’ DTC is activated by the receiving ECU but indicates a malfunction within another system which communicates with this ECU.
2. The cause of the DTC must be sought in the system from which it originates.

Example:
1. [ECU 1] detects an incorrect or missing signal from [sensor A].
2. [ECU 1] sets [DTC 1] (In this specific case, an open circuit DTC).
3. [ECU 1] constantly informs [ECU 2] about the status of [sensor A] via CAN messages.
4. Since the data received from the sensor is not available or not plausible, an ’empty’ CAN message is sent from [ECU 1] to [ECU 2].
5. [ECU 2] interprets the empty message as being out of the expected range and sets the ‘out of range DTC’ [DTC 2].

PACCAR MX (2004 Emissions) Fault Code: U186F CAN Communication – Message (PROPB_SW) Not Available, Variable Speed Limiter Set Switch from Steering Wheel Switches

SET CONDITIONS:
This DTC is set when a CAN message is received correctly, but the content (signal value or status) is not available.

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:
A malfunction in the system from which the message originates