Why is it that these problems only happen at the most inconvenient times, this Land Rover was on the way to catch a ferry?
Land Rover Discovery Electric Window Problems? Common problems with Land Rover Discovery electric windows include:
- Blown fuse
- Faulty switches
- Faulty body control module (BCM)
- Faulty window motor
- Faulty window regulator
- Faulty wiring
In this guide, we’ll look at each of the most common faults and what you can do to fix them.
Check The Window Fuses?
In the interest of getting your problem solved quickly, let’s not overlook the most common simple fix, this isn’t technical and won’t take very long
The fuse box is located under the dash panel, use a coin to open the two tabs. Check the fuse label for the correct fuse number, remove and check filament and replace if blown.
Use the correct amp-rated fuse usually a 30 amp green blade type. If the new fuse blows too, it suggests a short in the wiring or a failing window motor. If the fuse is good, continue on the diagnostic journey.
How Do Land Rover Electric Windows Work?
I like to keep things simple, I’m guessing you just want your window to work, not a crash course in auto electrics. However, having an outline of how it works will help speed up the fault-finding process
Cars made in the last 20 years, I call them modern classics, use control modules. A control module is basically a computer that receives inputs from sensors and input commands from the driver and other control modules and then in turn sends an output.
A modern classic may have many control modules depending on how sophisticated it is, typical control modules include:
- Engine control module (ECM) also known power-train control module (PCM) – controls engine management
- Transmission control module (TCM) – controls transmission management
- Body control module (BCM) – controls body electrical management
So What Does A BCM Do?
A real example in the case of our Land Rover is the pressing of the window switch sends an input signal to the BCM, which in turn sends a power supply to the window motor, making it go up or down.
What this means in effect, is that, unlike pre-control module cars, there’s no actual direct wiring connection between the window switches and the window motor.
Yes, it’s a more complex system than a pre-control module wiring layout, but offers greater advantages. Less wiring, more efficient use of power, greater control of power, and in theory diagnostics are easier.
I say in theory because you’ll need dealer-level diagnostic. I worked in a Land Rover shop with full dealer level diagnostics, fault finding is faster, easier, and more accurate.
In the case of our electric window fault, it would be standard practice to plug in the diagnostic laptop and read fault codes directly from the BCM.
In addition, with the laptop, the windows can be commanded up or down through the BCM, this allows the technician to see all the input signals and the outputs. It’s the most efficient way to pinpoint the fault, but we don’t have dealer-level diagnostics.
So instead we’ll use our ears, as you’ll learn, a laptop is not the only way to fault find.
Fastest Way To Fault Find Land Rover Power Windows
There may be many reasons why your Land Rover windows aren’t working, to help pinpoint the component that’s failed, a little detective work is needed.
I’ll try and keep this low tech and simple, we’re going to use just our ears initially to help narrow the field of possible faults.
Diagnosing by sound
- When you hit the window switch do you hear any noise at all? Listen carefully, a clicking may be heard from the door and/or from the dash board area. (ignition switch on)
- If a clicking noise is heard, then you can likely rule out a problem with the switch and it’s associated wiring.
Click sound from the door
- If a clicking is heard from the door, it’s likely the switch, wiring, BCM and window motor are all OK. The problem is likely to be a binding, worn, faulty or broken window regulator, move on and check it out. (see below).
- If you can’t hear a clicking from the door, you may have a blown fuse, wiring fault, faulty window motor or faulty BCM.
Window motors give lots of trouble, so it’s high on the list of possible failures.
Click sound from glove box
- Now, open the glove box, can you hear a clicking noise as you hit the window switch.
- If you can, then it’s likely your switch and wiring to the BCM and the BCM are all OK. The problem is somewhere between the BCM and the window motor. More on window motor testing below.
- If you can’t hear a clicking from the glove box, you may have a faulty switch, wiring to BCM or faulty BCM.
Faulty BCM’s are a common Land Rover fault, more on the BCM below.
Testing Electric Window Switches
For the purposes of organization, I have ordered these components, not in order of how likely they are to fail, but in order of how they are found on a wiring diagram. So first up is the window switch.
A symptom of a faulty window switch is the absence of clicking noise from the door or the glove box area. If you do hear clicking from these areas as you hit the switch, your switch is OK, it’s not at fault.
Removing the switches from the center console will often reveal the problem. Disconnected, loose wiring, broken wires, or bad connections are common and will obviously cause problems. Some Land Rover switches can be interchanged from left to right, if your block connectors are the same, swap left to right and test, if it now works, you found your problem.
Testing the switch will require a voltmeter. We’re not concerned with actual voltages here, but we do want to see whatever voltage you have, change as the switch is activated. No change in voltage indicates a faulty switch.
Testing The BCM
The only foolproof way to test the BCM is with dealer-level diagnostics. Next, best is a voltmeter and a wiring diagram, that’s correct for your model, year, and equipment spec level.
That said, if you wish to test the BCM, you can do some tests even without a wiring diagram. The color code of your switch wiring could be traced to the BCM input pin and test the input signal when the switch is toggled.
Similarly, the wiring color of the door motor (body side block connector) could be traced to the output pins of the BCM and checked for a voltage when the switch is activated.
But by far the easiest test is the sound the BCM makes when activated. As explained earlier if the BCM makes noise as you hit the window it’s likely OK.
If you don’t hear any noise and you know the switch is good, you can remove the BCM and check the circuit board for a known failure, solder fatigue. The solder cracks on the circuit board and can be easily repaired with a soldering iron and some wire.
Testing The Window Motor
Clicking noise from the door area is the sound the window motor makes as power is applied. The click is the motor inbuilt circuit breaker doing its job.
So a click sound from the door usually means the motor and all the wiring is good, and the problem usually revolves around a binding window regulator. (mechanical arms that lift window) More on this below.
But there are exceptions, sometimes the motor may be clicking and the regulator is good. I’ve found motors that will just click when connected to the window regulator but will operate as normal when disconnected, it’s a failed motor.
Motor gears stripping out is also common, this will be an obvious sound, you’ll hear the motor run and run as long as you hold the switch. The only repair here is to replace the motor.
But no noise at all at the door and but a clicking noise at the glove box, as discussed earlier, does suggest a problem with the motor or the wiring. Check the voltage at the motor, you’ll need to remove the door first cover.
After removing the door cover screws, remove the small black door opening trim, then pull the door cover firmly to remove.
It’s not important which way you connect the probes, when connected set the meter to voltage, ignition on, and toggle the window switch.
The voltage will show minus when the window switch is toggled one way and plus voltage the other.
- If you have no voltage, probe the other side of the connection to eliminate a problem with the two pin block connector itself.
- Still no voltage? Check again when wiggling the door wiring and operating the window switch.
Broken wiring in the door loom is very common, constant flexing as the door opens and closes causes them to break.
Checking The Window Regulator
The window regulator is the mechanical assembly the makes the window go up and down, they give lots of trouble. Problems usually arise from general wear and tear, and a lack of adequate lubricant on the window runners. The regulator moves in a scissor-type action.
Nylon bushings on the end of the scissor arms run inside rails or runners, they wear out, break and derail. When the arms derail, the window stops working, and often the untethered arm will get bent out of shape by the window motor.
Broken spot welds are another common fault with the regulator. The frame welds simply fatigue and break, a simple re-welding will fix the problem, but you’ll need to remove the regulator from the door.
Stripped teeth from the regulator’s arm can happen, this will cause the window motor to slip and may also damage the gear of the window motor. Replacing the regulator is the only fix here.
You can find a complete guide to replacing a Land Rover Discovery window regulator and window glass here “Landrover window regulator removal”.
Disco 2 window won’t go up? The regulator’s arm has likely derailed, caused by broken bushings on the end of the arms. If the regulator isn’t damaged, the bushings can be replaced.