Troubleshooting

(Table 91, contd)
Diagnostic Trouble Codes for the Engine Pressure Sensors
J1939
Code
Description
Notes
3251-4 Particulate Trap Differen-
tial Pressure : Voltage Be-
low Normal
The ECM detects that the signal voltage from the DPF differential pressure sensor is less than 0.2 VDC
for 1.8 seconds.
The ECM will use the default value for the DPF differential pressure while this code is active. The de-
fault value is −0.1 kPa (−0.01 psi).
If equipped, the warning lamp will flash. The engine will be derated.
102-20 Engine Intake Manifold
#1 Pressure : Data Drifted
High
The ECM detects the following conditions:
The intake manifold pressure is greater than 7 kPa (1 psi) above the barometric pressure for at least 5
seconds.
The engine is not cranking.
The battery voltage is greater than 10 VDC.
The engine will be derated.
102-21 Engine Intake Manifold
#1 Pressure : Data Drifted
Low
The ECM detects the following conditions:
The intake manifold pressure is greater than 7 kPa (1 psi) below the barometric pressure for at least 5
seconds.
The engine is not cranking.
The battery voltage is greater than 10 VDC.
The engine will be derated.
The following conditions must exist before any of the
above codes will become active:
• There are no active 3509 codes.
• There are no active 168 codes.
The following background information is related
to this procedure:
The 5 VDC sensor supply provides power to all 5
VDC sensors. The ECM supplies 5.0 ± 0.1 VDC to
each of the pressure sensor connectors. The sensor
supply is output short circuit protected. A short circuit
to the battery will not damage the circuit inside the
ECM.
Pull-up Voltage
The ECM continuously outputs a pull-up voltage on
the circuit for the sensor signal wire. This pull-up
voltage is required for correct sensor operation and
diagnostics.
When the sensor is disconnected, this pull-up voltage
can be measured at the harness connector for the
sensor.
192 UENR0612-07
Circuit Tests
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