ROD 1M1725 - Caterpillar

This procedure covers open circuit diagnostic codes and short circuit diagnostic codes that are associated with the following sensors:
Intake manifold temperature sensor
Coolant temperature sensor
Exhaust gas temperature sensor
Fuel temperature sensor
Air inlet temperature sensor
DOC inlet temperature sensor
DPF inlet temperature sensorThe following background information is related to this procedure:The troubleshooting procedures for the diagnostic codes of each temperature sensor are identical. The temperature sensors have two terminals. The signal voltage from each sensor is supplied to the appropriate terminal in the P2/J2 connector or the P1/J1 connector.Pull-up VoltageThe 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.
Illustration 1 g03775307
Schematic diagram for the engine temperature sensors
Not all connectors are shown. Refer to the appropriate Electrical Schematic.
Note: The engine may be equipped with a combined intake manifold pressure/temperature sensor or an individual intake manifold temperature sensor. Refer to the appropriate Electrical Schematic
Illustration 2 g03625277
Typical view of the P2 pin locations for the temperature sensors
(23) Engine fuel temperature sensor ground
(38) Engine fuel temperature sensor signal
(55) Intake manifold temperature sensor signal
(57) Coolant temperature/intake manifold sensor signal
(58) Intake manifold temperature sensor ground
Illustration 3 g02868180
Typical view of the P1 pin locations for the temperature sensors
(19) Air inlet temperature sensor signal
(20) Air inlet temperature sensor ground
(79) DOC inlet temperature sensor ground
(80) DOC inlet temperature sensor signal
(81) Exhaust gas temperature sensor ground
(82) Exhaust gas temperature sensor signal
(83) DPF inlet temperature sensor ground
(84) DPF inlet temperature sensor signal
Table 2
Troubleshooting Test Steps Values Results
1. Check for Diagnostic Trouble Codes
A. Connect to the electronic service tool.
B. Turn the keyswitch to the ON position.
C. Access the "Active Diagnostic Code" screen on the electronic service tool.
Wait at least 30 seconds in order for the