2008 Mercedes-Benz GL-Class GL 320 CDI, GL 450, GL 550 Operator's Manual (P/N 164 584 74 81)

The 2008 Mercedes-Benz GL-Class Operator's Manual covers the GL 320 CDI, GL 450, and GL 550, with U.S. and Canadian equipment distinctions. This is Part No. 164 584 74 81, Edition A 2008.

• Driving controls: SmartKey and KEYLESS-GO operation, starter-switch positions, gear-selector functions, steering-wheel shifting, and automatic-transmission emergency operation.

• Traction and suspension: 4-ETS, ESP, air suspension, ADS, Downhill Speed Regulation, Parktronic, and equipment-specific off-road controls.

• Occupant protection: Occupant Classification System, side-impact and window-curtain air bags, seat belts, LATCH anchors, and rear-window override operation.

• Comfort and visibility: Climate-control variants, exterior lighting, windshield and rear-window wipers, and power-window and sunroof synchronization.

• Practical procedures: Active-head-restraint resetting, halogen-bulb replacement, diesel fuel-system bleeding, battery removal and installation, and emergency engine shut-down.

• Warning interpretation: Instrument-cluster warning lamps, multifunction-display troubleshooting tables, and regional tire-pressure-monitoring systems and restart procedures.

Written for the vehicle operator, this manual supports routine checks and owner procedures; technicians can also use its operating descriptions when assessing a complaint before repair.

Vehicle Controls and Equipment Variants

Illustrated cockpit, instrument-cluster, center-console, and overhead-control references identify switches and displays. Separate center-console views distinguish vehicles with and without the enhanced off-road package.

That package adds LOW RANGE and center/rear differential-lock instructions. Vehicles without it have an off-road driving program. Air-suspension coverage explains automatic ride-height changes and ADS settings, while Distronic is identified as Canadian-market optional equipment.

Climate-control coverage distinguishes the standard system from optional 3-zone automatic climate control. Tele Aid controls and status indications are described as originally equipped; full COMAND and Voice Control instructions are separate publications.

Warning Messages and Tire Monitoring

Tables pair warning lamps and display messages with possible causes and suggested responses. These references help distinguish expected operating behavior from a fault, including passenger-air-bag status, charging-system problems, and suspension warnings.

Tire-monitoring instructions distinguish U.S. TPMS from Canada's Run Flat Indicator and optional Advanced TPMS. Inflation guidance refers to the vehicle's own pressure labels; rim and tire tables provide model-specific fitment information.

Battery Service and Practical Hints

Battery access: Removal and installation instructions cover the under-seat VRLA battery, the designated carpet-cutting area, and the seat movement needed for access. For a discharged battery, the manual explains the external power requirement before the seat can be repositioned.

The manual recommends a qualified technician for this technically demanding battery work. A specific caution warns that loosening battery clamps with the engine running or the SmartKey inserted can severely damage the alternator and electronics.

References for restoring functions after a power interruption cover door-window, sunroof, and power-folding-mirror synchronization.

Head restraints and lighting: Active-head-restraint resetting differs for vehicles with and without rear-seat entertainment; the equipped version uses a reset tool. Bulb instructions distinguish halogen replacement from high-voltage Bi-Xenon work referred to qualified technicians. Restraint-system service also requires qualified personnel.

Diesel restarting: The fuel-system bleeding procedure addresses air entering the system after an empty tank and sets limits on further starting attempts.

Fuses and emergency shut-down: The PDF explains fuse-box access and emergency engine shut-down. Fuse assignments and amperages are provided on a separate chart kept with the vehicle tool kit.

Separate poly-V-belt layouts distinguish the GL 320 CDI from the GL 450/GL 550 and label the driven accessories and tensioner. Other practical procedures include SmartKey-battery and wiper-blade replacement.

A Preview of Fuel Requirements and Oil Capacities

These fuel requirements and oil capacities are a small selection of the operating data included in the manual.

The GL 450 and GL 550 require premium unleaded gasoline with a minimum posted octane rating of 91. The GL 320 CDI requires ultra-low-sulfur highway diesel with no more than 15 ppm sulfur.

The capacity table lists engine oil with filter at 9.0 US qt for the GL 320 CDI and 9.5 US qt for the GL 450 and GL 550.

Searchable Text and PDF Chapter Bookmarks

Finding controls and procedures: Searchable PDF text and embedded bookmarks provide access to the main chapters and many subsections. The control illustrations and poly-V-belt references are readable when enlarged.

Supplied as one printable English-language PDF with 601 pages: 594 manual pages, one cover spread, one publication-information page, and five blank pages. All are included in the total.