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On average, the cost for a Mercedes-Benz 400E ECM-Power Relay Replacement is $209 with $114 for parts and $95 for labor. Prices may vary depending on your location.
| Car | Service | Estimate | Shop/Dealer Price |
|---|---|---|---|
| 1993 Mercedes-Benz 400EV8-4.2L | Service typeECM-Power Relay Replacement | Estimate$342.95 | Shop/Dealer Price$417.44 - $601.54 |
| 1992 Mercedes-Benz 400EV8-4.2L | Service typeECM-Power Relay Replacement | Estimate$322.95 | Shop/Dealer Price$397.47 - $581.59 |
Vehicle development has evolved over the past several decades to a point where it seems every vehicle function is controlled by a computer, right down to the engine itself. This is actually the case for the engine and its related functions as it is controlled by the engine control module, or ECM. The ECM monitors and adjusts operation and power distribution to the fuel supply and injection systems, engine timing, exhaust gas recirculation, emissions, ignition system, and several other systems. In order to dispense power to operate these other systems, the engine control module requires power itself.
The power distribution center, or fuse block, located under the hood houses most or all of the vehicle’s fuses and relays. It contains a relay for the ECM that is powered up when the ignition key is turned to the on position. This ECM power relay acts as a switch that supplies power to the ECM. When the ignition is turned off, power switches inside the ECM relay and it no longer receives battery power. If the ECM power relay stops switching as it should, you will experience vehicle problems. When the relay is stuck open, no power will be delivered to the engine control module and the vehicle won’t start. If the relay is stuck closed, constant power will be sent to the ECM even with the engine turned off and the battery will drain.
The ECM-power relay is verified that it needs to be replaced. The relay is located in the engine main fuse relay control box.
The defective ECM-power relay is removed from the control box by pulling it straight up and out of socket.
The new ECM-power relay is installed into the socket and the engine scanned for codes.
The engine is started and the ECM-power relay is tested for proper operation.
The vehicle is road tested for proper operation of the ECM-power relay and is then checked for codes.
The ECM power relay should last the lifetime of your vehicle unless there is a power distribution problem or moisture that causes it to fail. If your vehicle won’t start, have one of our expert technicians diagnose the problem and replace the ECM power relay if necessary.
Although it is extremely unlikely the ECM relay will cause your vehicle to stall or create a safety concern, your vehicle may not start or the battery may die while the ignition is off. In either case, you will need to replace the ECM relay.
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