bmw 335i oil temp gauge never moved, check engine light

• 2022-11-29

Fault description: bmw 335i oil temp gauge never moved, check engine light

Diagnosis process:

1. During the factory inspection, the vehicle oil temperature is not displayed on the instrument panel (the pointer of the oil temperature gauge is always at the lowest point: 70 degrees);

2. Check the vehicle fault code, there is no relevant fault code, self check the instrument, and no problem is found in the self check of the oil temperature gauge;

3. Read the oil temperature of the vehicle with the ISID, and it is always displayed as - 51 ° C, whether it is cold or hot;

4. It is doubted that the vehicle transportation mode has not been completely deleted, and the same fault phenomenon still exists after deleting the transportation mode again;

5. After programming the vehicle, the vehicle still cannot display the oil temperature (the vehicle is upgraded to the program version: E89X-10-12-503);

6. Check the circuit. x6238 Pin1-x6003 Pin57 is conductive, and the pins are free of corrosion. x6238 Pin2-X6003 Pin43 is conductive, and the pins are free of corrosion. Check the plug and DME pins, and no water ingress is found. There is no mutual short circuit between wires and conductors;

7. The circuit diagram shows that the grounding of the sensor is the internal grounding of the DME. Lead out the grounding wire of the sensor (X60574 pin2) and ground it directly on the body. The oil temperature of the vehicle can be displayed normally.

8.Check that the resistance of X60003 Pin43 to ground is infinite;
Solution: The engine oil temperature gauge does not display the engine oil temperature because the components inside the DME are damaged, so the engine oil temperature gauge is not grounded (the lowest engine oil temperature is always displayed: 70 degrees). The DME needs to be replaced

Case study: After all, DME is an important component. At this stage, it is customary to judge electrical fault by borrowing parts, and we dare not make a conclusion without borrowing parts (especially DME).

This fault is not a particularly troublesome circuit problem. By analyzing the circuit diagram and the structural principle of the module, the oil temperature display is normal after the grounding of the oil temperature sensor is directly led to the vehicle body without passing through the internal lead of the DME; Then measure that the grounding pin corresponding to the module is disconnected from the body, so as to judge whether the DME is damaged.