Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Differential Electronic Module (DEM) (2008): Function: PRETENSIONING
The function of the four wheel drive system is based on there being a speed (RPM) difference between the front wheels and the rear wheels. This speed (RPM) difference can affect torque performance in certain driving situations. The task of the pre-tensioning function is to improve torque performance, in particular when pulling off from being stationary, without affecting other properties in the system.
The pre-tensioning function is achieved by the electric feed pump starting as soon as the engine has started. During acceleration, when pulling off, or during other situations that means that the oil pressure's desired value is not achieved by the clutch's flow, the feed pump, together with the check and by-pass valve, builds up a pressure (1.0 MPa). This pressure affects the clutch driven plates and can therefore transfer greater torque to the rear axle. The pre-tensioning function is controlled by the software so that activation only occurs when necessary.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.