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.
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HOMESERVICE MANUALSVOLVO2017XC90 T8 EXCELLENCEREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCEENGINE CONTROL SYSTEMSIGNITION AND CONTROL SYSTEMS - SPECIFICATIONS, ELECTRICAL/ELECTRONICDESCRIPTION OF CAUSES FOR SYSTEM REQUESTED AUTOSTARTDESCRIPTION OF CAUSES FOR SYSTEM REQUESTED AUTOSTART, VEA GENERATION 1 [2016-2018]REQUEST AUTOSTART IN AUTOSTOP, BRAKE VACUUM
2017 Volvo XC90 T8 Excellence
Request AUTOSTART In AUTOSTOP, Brake Vacuum
2017 Volvo XC90 T8 ExcellenceSECTION Request AUTOSTART In AUTOSTOP, Brake Vacuum
Causes of system requested autostart in autostop:
- Incorrect pressure (vacuum too low) in the brake booster
Checks:
- Check the brake booster's function and non-return valve for air leaks. With the engine just shut off the vacuum in the brake booster should be enough for a few vacuum assisted brake attempts.
- Check for air leaks in the vacuum hoses between the brake booster and motor.
- Check that the vacuum pressure sensor works properly.
HINT: Read off the air pressure in the brake booster via Diagnostics/Components/Diagnostic Sequences/Vehicle Dynamics Domain Master (VDDM), BCM in VDDM/Parameters.
RENDER: 1.0x
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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.