Why is the Mercedes GL550 motor not responding?
3 Answers
Mercedes GL550 motor failing to start indicates that the vehicle must have a discharge fault. The possible causes for this issue include: battery depletion due to the battery itself; electrical devices in the vehicle being in an operational state; internal short circuit in a control module causing leakage; or grounding in the wiring. Vehicle transfer speed: After running the vehicle for 10 minutes, the starting voltage of the battery was tested at 11.5V, and the charging voltage at 14V, both within normal ranges, thus ruling out the battery as the cause of the vehicle's failure to start. Using the XENTRY diagnostic tool to read fault codes: The engine control module, front SAM, rear SAM, etc., all reported faults of excessively low supply voltage.
When I first drove the Mercedes GL550, I encountered a situation where the starter motor didn't respond—it was really frustrating. Turning the key produced no reaction at all. It was most likely due to a dead battery or loose connections, especially since battery aging or cold winter temperatures can easily cause power loss. Next, you should check the starter motor itself—whether the carbon brushes are worn out or the coils are burnt. The motor is located beneath the engine, and if you hear no sound, that's suspicious. Don’t forget the fuse box—look near the glove compartment, as a blown starter fuse is common. The anti-theft system can also be a culprit, so try reinserting the car key. Make sure the gear is in P or N, as an automatic transmission stuck in the wrong position won’t respond. I also recommend checking the battery voltage—just use a multimeter for a quick test. If the reading is low, charge it immediately or replace it. Also, inspect for poor wiring connections—wiggle the motor plug to see if anything changes. Regular maintenance is key to avoiding breakdown headaches.
When the starter motor doesn't respond, I usually start by checking the battery. Open the engine hood and measure the voltage between the positive and negative terminals - if it's below 12V, that might be the issue. Try using jumper cables as a temporary solution. Next, check the fuses. For a Mercedes GL550, the starter fuse is located in Zone B of the fuse box, around position 47 - just replace it if blown. The relay is crucial - listen for a "click" sound in the engine compartment when starting; if absent, the relay might be faulty. Then inspect the starter motor connector for looseness or corrosion, and clean it by unplugging and reconnecting. If the anti-theft system is acting up, try turning it off and restarting with the key. Worn carbon brushes in the starter motor are common in older vehicles - remove and inspect them. Finally, ensure the battery ground connection is good; clean off any corrosion with sandpaper. Follow these steps methodically - don't take shortcuts or disassemble randomly.
