The Engine Control Module (ECM) relay is an important component in a vehicle’s electrical system. It controls power to the ECM, which is essentially the vehicle’s computer that manages engine functions. Knowing the location of the ECM relay can be helpful when troubleshooting electrical issues. In this article, we will discuss what the ECM relay does, symptoms of a bad ECM relay, and most importantly, where to find it in some of the most common vehicle makes and models.
What Does the ECM Relay Do?
The ECM relay is responsible for providing power to the vehicle’s engine control module. It acts like a switch, allowing power to flow to the ECM when the relay is switched on. When you turn the key in the ignition, it activates the ECM relay, sending voltage to the ECM so it can power up and communicate with the various engine sensors and actuators.
Some key functions of the ECM relay include:
- Turns on the ECM when the ignition is switched on
- Cuts power to the ECM when the ignition is switched off
- Protects the ECM from electrical spikes and surges
- Allows the ECM to reset or reboot if needed
Without the ECM relay sending power, the ECM would not activate and be able to control essential engine systems like the fuel injectors, ignition timing, idle speed control, and more.
Symptoms of a Bad ECM Relay
Here are some common signs that your ECM relay may be having issues:
- Engine will not start – If the ECM is not powered on, it can’t activate the starter.
- Stalling soon after starting – The ECM needs consistent power to stay on and keep the engine running.
- Rough idle – The ECM controls idle speed and if it’s intermittently powering off, the idle will be irregular.
- Engine misfires or cuts out – The ECM controls ignition timing so a bad relay can cause misfires.
- Electrical accessories like lights and radio not working – The accessory power circuits are often routed through the ECM relay.
If you notice any of these symptoms, especially an engine that won’t start or stalls immediately, it’s a good idea to test the ECM relay first before moving on to other components.
ECM Relay Locations by Vehicle Make & Model
Now let’s take a look at where you can find the ECM relay in some of the most popular vehicle makes and models:
Honda Accord
The ECM relay is located under the dash on the driver’s side for 6th generation 1994-1997 Honda Accords. Look next to the ECU by the hood release. On 1998-2002 Accords, the relay is still under the dash but closer to the steering column.
Toyota Camry
In 1992-1996 Toyota Camrys, the ECM relay is positioned near the accelerator pedal under the dash. You’ll find it on the wall separating the engine bay from the interior. On 1997-2001 Camrys, the relay is under the hood on the passenger fender near the battery.
Ford F-150
Look under the hood near the battery on the passenger side of 1999-2003 Ford F-150s. The ECM relay will be mounted on the front wall of the engine bay. On 2004-2008 models, it moves to a junction box on the back driver’s side wall, still under the hood.
Jeep Grand Cherokee
The ECM relay is plugged into the Power Distribution Center in the engine bay of 1999-2004 Jeep Grand Cherokees. It’s located near the front driver’s side headlight. For 2005-2010 models, open the fuse box under the hood on the driver’s side to find the ECM relay.
Toyota Corolla
In the engine bay near the battery on the driver’s side is where you’ll find the ECM relay on ninth generation 1998-2002 Toyota Corollas. It’s mounted to the side wall. On 2003-2008 Corollas, the relay moves further back, still on the driver’s side engine wall.
Nissan Altima
The ECM relay on 2002-2006 Nissan Altimas is under the dash closer to the glove box. Remove the cover to access it. On 2007-2012 models, it’s under the hood on the rear engine firewall, passenger side, near the strut tower.
Chevrolet Silverado
In Chevrolet Silverados from 1999-2006, the ECM relay is located under the hood on the driver’s side above the front wheel well. Open the fuse box cover to find it. The 2007-2013 Silverado moved it to an under-hood junction box on the passenger side near the rear.
Toyota RAV4
On 2001-2005 Toyota RAV4s, the ECM relay is located under the dash closer to the driver’s side. You’ll need to remove a trim cover to see it. On 2006-2012 models, it’s under the hood on the rear driver’s side firewall. Open the fuse box to find it.
Honda Civic
The seventh generation 2001-2005 Honda Civic has its ECM relay under the hood near the strut tower on the driver’s side. For 2006-2011 Civics, it’s towards the back of the engine bay on the rear firewall, passenger side.
Ford Focus
Look under the hood near the battery on the passenger side in 2000-2007 Ford Focuses to find the ECM relay. It’s mounted on the front wall of the engine compartment. In 2008-2011 Focuses, it moves to the same spot as the fuse box, rear driver’s side.
Conclusion
Knowing where the ECM relay is located in your vehicle is important if you ever need to test or replace it. While the location varies between vehicle makes and models, it’s usually in the engine bay, under the dash, or in a fuse box. Use the guide above to quickly find the ECM relay in some of the most popular vehicles. If you’re experiencing potential symptoms of a bad ECM relay, consult your owner’s manual for the exact location before testing and replacing it.
| Vehicle Make/Model | ECM Relay Location |
|---|---|
| Honda Accord | Under dash, driver’s side (1994-1997) Under dash near steering column (1998-2002) |
| Toyota Camry | Under dash by engine wall (1992-1996) Under hood, passenger fender (1997-2001) |
| Ford F-150 | Under hood, passenger side (1999-2003) Rear driver’s side wall (2004-2008) |
| Jeep Grand Cherokee | Engine bay, driver’s side (1999-2004) Under hood fuse box, driver’s side (2005-2010) |
| Toyota Corolla | Engine bay, driver’s side (1998-2002) Rear driver’s side wall (2003-2008) |
| Nissan Altima | Under dash near glove box (2002-2006) Rear firewall, passenger side (2007-2012) |
| Chevrolet Silverado | Engine bay, driver’s side (1999-2006) Under hood junction box, passenger side (2007-2013) |
| Toyota RAV4 | Under dash, driver’s side (2001-2005) Rear firewall, driver’s side (2006-2012) |
| Honda Civic | Engine bay, driver’s side (2001-2005) Rear firewall, passenger side (2006-2011) |
| Ford Focus | Engine bay, passenger side (2000-2007) Rear driver’s side (2008-2011) |