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.
Reduce Speed, Basic Function - GF30.30-P-1001A
Model all (4xWD)
Model all (CAR)
REDUCE speed
The vehicle speed is reduced by reducing the drive torque. The following activities are started in this case:
- Engine torque reduction
The engine management system implements the "Reduce engine torque" request.
- Gear downshift (vehicles with automatic transmission)
The transmission management system implements the "Shift down gear" request.
- Service brake actuation
If the drive torque reduction is not sufficient to decelerate the vehicle, the brake system actuates the service brake.
| Additional basic functions | |||
| Torque coordination, basic function | GF07.10-P-1060A | ||
| Gearshift system, basic function | Model all with transmission 700.420/421/422/423, 724.033/044/045/103/114/115/120 | GF27.60-P-1002A | |
| Model all with transmission 725.0/1 | GF27.60-P-1002B | ||
| Brakes, basic function | GF42.00-P-9900A |
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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.
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