Symptoms
One or more lock lights never come on, the centre lock drops out (and takes the rear with it), or locks release when engine revs fall.
The fix, step by step
- Follow the MBWorld owner who fixed his 2005 G 500.
- Pull the vacuum hose at the transfer case and test for vacuum there.
- Then work back toward the source: intake manifold, the vacuum reservoir in the front-left wheel well, then the switchover valve block on the firewall, teeing a gauge into each segment.
- His leak was a split plastic connector inside a rubber Y-piece under the brake booster.
- Replace brittle hoses and weak check valves as you go, then flush and bleed the hydraulic side.
Tools & part numbers
- Hand vacuum pump with gauge
- tee fittings
- vacuum line and connectors
- diff-lock vacuum reservoir 102 070 00 68 if cracked
- brake bleeder for the hydraulic slaves
Where to buy the parts
Diff-lock vacuum reservoir 102 070 00 68Expedition Imports ↗Amazon ↗
Vacuum hose / check valve (G 500)FCP Euro (search) ↗
Rear brake / rear locker hoseExpedition Imports ↗Amazon ↗
Hunting a used or discontinued part? Search eBay Motors for Mercedes-Benz G-Class W463 parts →
Rated for a competent home mechanic with a decent tool kit. Confirm torque figures, fluids and procedures against the factory service manual for your VIN, support the truck on stands rather than a jack, and work at your own risk (disclaimer). Some parts links are affiliate links, which pay us a small commission at no cost to you.