My Key Won’t Turn Ignition Mercedes-Benz Problem

• Unable To Turn The Key
• Unable To Start The Car
• I can Turn The Key, but the car will not start
• Ignition Key Faults

Drive Authorization System (DAS) is the Mercedes Immobilizer system that checks drive authorization every time you insert the key into the ignition and try to start the car. DAS was introduced back in 1996 and has had several security improvements. The main DAS versions are DAS 2, 2A, X, and 3.

New drivers always experience this at least once, so we thought we would include it. If the key does not turn in the ignition, try moving the steering wheel as you try to turn the key. The steering wheel will feel completely solid if you try to move it in one direction, and it may move slightly in the opposite direction. Push the steering wheel in the direction that allows a little movement, then insert the key and try to turn the key again. You can put pressure on the steering wheel and also try shaking the steering wheel. As you do this, insert the key into the ignition and try to turn the key. DO NOT TRY TO FORCE THE KEY INTO THE IGNITION. The steering column lock is a security feature that all car manufacturers incorporate into the cars.

The battery in the car may be defective, as it does not provide the necessary voltage for the ECU and the N73 Electronic Ignition/Starter Switch (EIS)  to function correctly. If the battery is dead or has low voltage / under voltage, the CAN communication between EIS and N72 may not function properly. The EIS in the Mercedes-Benz has a coil that induces a magnetic field on the Smartkey, which causes the key to responding to the car with a specific rolling code. Using a 10-dollar multimeter like this, you can check your good battery before proceeding. The car battery should indicate at least 12.8 volts without the car running. When the engine is running, it should be over around 14.4 volts. If you need a replacement battery for

If you have a metal blade key instead of the Smart Key Remote, it is possible that the key tumbler could be defective. While most Mercedes-Benz cars have the SmartKey, some models, such as the ML-Class, SLK Class, and Crossfire, used a metal blade key up to 2005. Some models suffer from defective vital tumblers. We have seen cars with as little as 20,000 miles where the tumbler goes bad. Make sure the steering wheel is not in a locked position, as mentioned above. Then insert the key into the ignition and gently jiggle the key without putting much pressure on the key, as do this. As the lock pins on the tumbler wear out, it will get harder and harder to turn your car’s ignition. Here is a video that will help you understand this problem. The video below shows the same problem on a GM, but the same principle applies to the older Mercedes-Benz that uses a metal blade key.

The EIS module could also explain why the key does not turn when ignited. Many car owners complain that their car starts fine on a warm or hot day, but the vehicle will not start on cold days. This may sound strange, but it is reported frequently. The EIS has processors soldered on the circuit board, and in many cases, the connections could be bad, or the processor itself is defective. The video below shows how the cold temperature causes the ignition switch to malfunction. The ECU could experience the same symptoms as well.

If you have this problem, you must install a new/virgin EIS. You can not establish a used unit because the EIS has to be paired/married to the car using Mercedes-Benz Star Diagnostic Software.

The key itself may be the reason why the car doesn’t start. The key may open the doors but not start the vehicle. In some cases, the transponder coil wires may disconnect and need to be resoldered, or the key’s processor could be defective. The simplest solution, in this case, would be to order a new key from the Mercedes-Benz dealer. Read What you need to order a new key for your Mercedes-Benz.

Electronic Control Module (ECU) is another reason the car doesn’t start. You will need to get a new ECU installed to solve this problem. You can not swap with a used ECU and expect it to work as the board is “married” to the car. Another solution would be to get a used ECU and switch the processor from the old circuit board to the used replacement ECU. Watch this video and see how MBCluster users on Youtube successfully cloned a Mercedes-Benz ECU!

NOTE: Avoid letting the car’s battery discharge while igniting the key. This could damage the key or the EIS.

What Scanner Can I Use to Troubleshoot Mercedes-Benz Ignition Problems?

If you’re experiencing problems with your Mercedes-Benz, a YOUCANIC full system diagnostic scanner can help you troubleshoot the issues. This advanced diagnostic tool can read and interpret the fault codes stored in your car’s computer system, providing detailed information about any problems with the engine, transmission, brakes, or other critical systems.

The YOUCANIC scanner can also perform diagnostic tests on various systems, including the ABS, airbag, and steering systems, to help pinpoint the root cause of any issues. With this information, you can make more informed decisions about repairs and maintenance, saving time and money on costly repairs.