CM850 Electronic Control System – FAULT CODE 1848

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Overview

Circuit: Intake Manifold 1 Temperature SMALL | MEDIUM | LARGE

Circuit Description

The engine intake manifold temperature sensor is used by the electronic control module (ECM) to monitor the engine intake manifold temperature. The ECM monitors the voltage on the signal pin and converts this to a temperature value.

The engine intake manifold temperature value is used by the ECM for the engine protection system and engine emission control.

Component Location

The engine intake manifold temperature sensor is located in the air intake manifold. 100-002 (Engine Diagrams) in Section E for a detailed component location view.

Shop Talk

The engine intake manifold temperature is monitored during engine warm-up. If the engine intake manifold temperature reading is not changing to match the engine operating conditions, the intake manifold temperature sensor is then determined to be stuck in-range and this fault code is logged. The ECM must not see engine speed for a period of eight hours before this diagnostic will run.

Possible causes of this fault code include:

• Stuck in-range engine intake manifold temperature sensor reading.
• High resistance in the engine intake manifold temperature sensor signal or return lines.

On-Board Diagnostics (OBD) Information (Euro 4 and Euro 4 Stage 1+ Certified Engines):

• The ECM illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
• The ECM turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. The MIL lamp and fault code can also be cleared using the INSITE™ service tool.
• The fault code will be cleared from memory after 40 consecutive drive cycles where the diagnostic runs and passes.

Refer to Troubleshooting Fault Code t05-1848