Bad Gem Module Symptoms

Car manufacturers, in a bid to make operability easy, have made several devices to regulate several components simultaneously. One of such component is the Gem module found in Ford and other vehicles. While this component appears useful, it might get bad due to leaky windshields, loose or short wires, etc., and start causing different car issues.

In this article, I will work through bad GEM module symptoms that you need to look out for that will quickly tell you your GEM has issues and needs fixing. However, before we explore these symptoms, let’s have an overview of what a gem module is and how it works.

bad gem module symptoms chevy

What is the GEM module in Ford?

A gem module, called Generic electronic module, is an automated device found in Ford vehicles that helps regulate and control the car’s electrical accessories. Some of which include the key fob, anti-theft alarm, cabin lights, signature lights, otherwise called daytime running lamps, power windows, door locks, back window decor, battery savers, etc.

While those asking what a gem module does have by now gotten their answers, it’s important to know how it works. Typically, a gem does two main jobs. Gems are built to interact with other electrical car components like the engine and transmission control module via the GEM sensors.

Then, use information from these sensors to determine how to regulate various electrical components. So when it goes bad, it can cause different electrical problems like lights twinkling, nonfunctional power windows, and sometimes complete loss of engine power.  

Symptoms of bad GEM module

The GEM module controls the majority of electronic components in your car. So it’s very likely that when a GEM is bad, most things that start malfunctioning are things that function with electricity.

Common symptoms of a bad gem module include lack of engine power, engine not starting, dead or drained batteries, and Wipers and rain sensors not working. Others may include lights twinkling or shutting off on their own, key fob not working, malfunctioning radio, etc.

Car not starting

One of the most noticeable ways to point out a bad GEM module is your car not powering up. And this can be traced to a bad power relay. The GEM works with the power relay that sends currents to various electronics.

However, when the GEM is faulty, it negatively impacts the power relay. Because the power relay isn’t functioning as it should, it will refuse to send the power needed to start your car. So, even if you turn the key inside the keyhole, your vehicle won’t respond. Here, you will notice that no lights or electronics on your dash are working.

Lights refusing to turn off or on

When the car is brought to a halt, the GEM allows the interior lights to stay on for at most 45 minutes before it shuts them out totally. So long as there is no input like opening or shutting the door, turning on the engine, etc., within this time, the lights will blackout.

However, if the GEM is bad, it may trigger some things like door opening and keep the lights on afterward. Sometimes, the lights could turn on when you’ve turned off your car; other times, the lights will illuminate even when driving. In other cases, the lights will refuse to turn on at all.

Locks malfunctioning

The GEM receives driver input to lock or unlock the car. However, when it is bad, it may not recognize when it needs to lock or unlock the car. So sometimes, it may keep the car unlocked. Aside from theft, one issue with car doors not locking properly is that it also affects the car lighting. 

While the GEM is supposed to leave the lights on for only 45 minutes after the engine is shut, if it detects any input, like doors unlocking, it will keep the lights on or flickering. What happens to some interior lights when you open your car doors? They come on, right? That’s exactly what happens when locks malfunction.

Drained or dead battery

When the GEM module is faulty, it causes your lights to stay on while driving or the car is parked. And in many cases, other car accessories like the radio will also stay on even with the key out of the ignition.

Because a faulty GEM will leave the lights and these accessories on, your battery gets drained over time. If this continues for long, you may soon have a dead battery. So, if your battery drains faster than it should or dies untimely, you may be dealing with a failing GEM module.

Engine stalling or not starting.

Because a faulty GEM affects the relay, your car may stall or not start. No starting issues may be due to the power relay not sending enough power to start the car. Or the battery not getting signals from the ignition relay switch itself.

More so, stalling will occur since there is a power disconnectiom and reconnection between the battery and relay. Stalling can also occur due to altered transmission resulting from GEM wires shorting out or getting too loose.

Key fob not working.

The remote control helps unlock the car via a sensor that the GEM reads. The GEM should unlock the driver’s door once the remote is pressed once and unlock all doors when pressed twice after three seconds of pressing it once. The same goes for locking.

However, when the GEM module is damaged or its sensors are faulty, it cannot read the input or signal from the key fob. Hence, the key fob is unable to open or lock your car. However, while the key fob not working might be caused by a bad GEM module, it could also result from a bad key fob battery.

Radio turns on itself without a key.

The GEM takes note of input made to turn on and off the radio and does so as required. All this is supposed to happen when the car is turned to the on position. However, when the GEM module is faulty, it may read wrongly, not knowing whether a car owner needs the radio on or off.

So it automatically turns the radio on even when the engine is off. If this happens, especially when the car is parked overnight, you may have to deal with a dead or drained battery in the morning.

Radio and wiper switch refusing to work.

In other cases, even if the key is turned on, the radio will not work since the GEM cannot get the correct input initiated by the car occupant.

The same goes for the wiper switch; if the GEM is faulty, it won’t respond to activate the wiper when the wiper switch is turned on. Here, the wiper may refuse to turn on or off when needed and, in other cases, turn on even without touching the wiper switch.

The security system is not working.

Another Ford 7.3 bad GEM module symptoms, or that of any Ford model, is the alarm not activating when needed. The GEM module works directly with the alarm system and activates it when something isn’t right. However, when the GEM module is faulty, it will fail to sound the alarm system or make any warning when required. 

The turn signal switch not working.

Another noticeable Ford F250 GEM module problems is the malfunctioning turn signal switch. Because a faulty GEM will fail to read or collect input from the turn signal, the turn signal will fail to turn even when pressed.

How to test the GEM module

Ford dealers usually do testing of the GEM module before replacing the GEM module or fixing a faulty fuse. This is to make sure they ascertain the condition of the module and determine whether it should be totally replaced or just repaired. And more importantly, to be sure the GEM is truly the problem. So, if you suspect your GEM might have any issues, here is how to test the gem module.

Method 1: Without accessing the GEM

This will help to diagnose if the GEM is working or not. And while this process is for a Ford Fiesta Mk6, it can apply to other Fords. Here, you will need to test every component the GEM module control. Here is how: starting from the rear heater window.

  • Press the rear heater window button and move the ignition to the II position. Take off your hand, then press the rear window heater button eight times in only six seconds. This will prompt the chime sound and turn on the indicator light on your dashboard, indicating you’re in test mode.
  • Repeat step 1 for others, like the wipers, when opening the door, etc. For every input successfully received by the GEM, you will hear a chime and illumination of the indicator light, indicating the GEM module is working.

Method 2: Accessing the GEM module

The above process is an easy way to know if the GEM is still okay and able to operate those components. However, another way to test GEM is to have the computer scanned for error codes or test the GEM physically. This process is recommended if you also want to know the physical condition of the GEM module.

  • Park your car in your garage or driveway. Turn off the ignition and all electrical systems. Activate the hand brake and set your gear in park or neutral, and also ensure all doors are locked properly.
  • Locate your GEM. In many models, it is found at the back of the fuse box or dashboard fuse panel. But it can also be anywhere, depending on your model.
  • Remove the GEM module from its housing after disconnecting the electrical connectors and the two bolts used to fasten it in place.
  • Using a multimeter or its alternative, like an oscilloscope, test the GEM module for error. In the absence of these tools, visit your local mechanic or dealer to help you out.
  • Replace if the module test proves it is faulty. You can get a new GEM module from a Ford dealership or other aftermarket vendors. Follow the steps above in the reverse order to install the new one.

How to reset the GEM module

Usually, after repairs or installation, some lights that came up while the GEM malfunctioned will remain on. So, you will need to reset it to clear them off. However, before you do the Ford GEM module reset, ensure you have fixed the module.

To do the Ford GEM module reset, connect a scan tool to your car’s OBDII port and scan for error codes. After which, you clear them (this is after fixing whatever caused the error codes to pop). With the error code cleared, all lights should have disappeared.

Another way to reset the GEM module is to disconnect the negative battery terminals for 20-30 minutes and then reconnect. A good way to know that the reset is done properly is this. The first time you insert the key after reset, every needle in the instrument panel will move to 100 and then back to Zero again. After which all accessories will start working well again

What about programming? Do I need to program my module after installation? Ford GEM module programming is essential for the GEM to function well after installation. Here, the GEM module is programmed with the new vehicle information.

GEM module locations

The Gem module could be found in different places in your Ford, depending on your model. However, for most models, Ford GEM module location is at the upper end of your fuse box. It could also be beneath the dashboard by the driver’s side

or behind the center of the instrument panel.

For example, while the  2000 F350 GEM module is at the Fuse box, recent Fords, like the 2020 models, have it in the dash. It’s worth noting that not all model years come with a GEM. For example, the 2004-2008 Ford F250 didn’t have a GEM module; instead, they used a smart junction block.

So, for those asking where their 2008 Ford F250 Gem module is, you may start looking for your smart junction block location instead since your model year doesn’t come with a GEM. Therefore, the best will be to consult your owner’s manual for your smart junction block location. Moreover, your manual will also let you know if you have the GEM in your model or not.

Can a GEM module be repaired?

A GEM module can be repaired depending on the condition. Most GEM gets bad due to a leaking windshield, letting water into the GEM module, which can also cause corrosion. It could also stem from short or loose wires, impacts from collision, or even overheating engines.

Short or loosed wires, bad sensors, or even light corrosion are issues that can be fixed. If, however, the GEM module gets broken due to impact from collision or aggressive corrosion or damage due to excessive heat, you may need an outright replacement.  

Here is a great way to repair the module without much hassle. However, if you don’t know how to repair Ford GEM module,  please visit your local auto shop or dealer.

What is the Ford GEM module recall?

The Ford GEM module recall is a recall made by Ford for vehicles experiencing the GEM module issues. The GEM controls certain functions like the wipers, cabin lights, alarm system, etc. Hence, when it is faulty, these functions may refuse to turn on, and in cases where they were already on, refuse to turn off.

The recall was made for all Ford 4.0 L SUVs and all-time four-wheel drives. To solve the problem, dealers will have to install a resistor in the GEM’s circuit. The first Ford GEM module recall was made in 2000, and as of 15 April 2000, affected vehicle owners were already notified about this recall. Vehicles built before 2000, including the early 99 7.3 Gem module, were part of those recalled.

Final words

Bad GEM module symptoms include lights flickering, power windows or wipers not working properly, accessories working without the key in the ignition, engine refusing to start, etc. Before proceeding to replace or repair the module, ensure you carry out a test, as the test will not only reveal whether the GEM is working or not but also its condition.

However, note that most GEM module issues are caused by leaky windshields letting water into the fuse panel beneath the dash between the GEM and fuse panel area. So when changing the GEM, you must also reseal the windshield and replace everything the water may have damaged. This may include the Fuse panel or a corroded wiring harness under the dash.

Osuagwu Solomon

Osuagwu Solomon is a certified mechanic with over a decade of experience in the mechanic garage, and he has over five years of experience in the writing industry. He started writing automotive articles to share his garage experience with car enthusiasts and armature mechanics. If he is not in the garage fixing challenging mechanical problems, he is writing automotive repair guides, buyer’s guides, and car and tools comparisons.

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