For your 1996 Mercedes-Benz diesel to start smoothly, two essential components are needed: fuel and heat. Let’s delve into how these systems function in your vehicle and what might cause starting problems.
Fuel delivery in your model, likely a W210 with an OM606 engine, is electronically managed. The injection pump, responsible for supplying fuel to the engine, is controlled by an electric shut-off valve. Furthermore, the engine computer determines the precise quantity of fuel injected. This calculation is based on input from the pedal sensor, which measures accelerator input and signals the computer to instruct the injection pump accordingly. A critical component in this electronic fuel management system is the K40 relay, which provides necessary power to these electronic components. Known issues with the K40 relay, often stemming from cold solder joints, can disrupt this power supply and lead to starting difficulties.
In addition to fuel, diesel engines, especially in colder conditions, rely on heat for ignition. This heat is provided by glow plugs, which warm the air sufficiently for fuel combustion during a cold start. The operation of these glow plugs is regulated by the glow plug relay. Without the initial heat from the glow plugs, starting a cold diesel engine becomes extremely challenging, if not impossible.
Older Mercedes-Benz models utilized simpler glow plug relay systems with a timer activated by the ignition switch. A dashboard light served as an indicator to the driver, signaling when to crank the engine and also alerting to potential glow plug failures. However, your 1996 W210 model incorporates a more advanced CAN bus system. This CAN bus acts as a communication network linking various electronic modules within your car, including the glow plug relay. Instead of a direct connection to the ignition switch, the glow plug relay in your W210 operates via this CAN bus network. A potentially problematic connector linking the glow plug relay to the CAN bus could be another area to investigate if you experience starting issues.
