ECS Strut Testing and Tool

I’m a big fan of the stock ECS system and because of that I have spent a lot of time working on it and repairing it. Once you understand the basics of the system you will find that the system itself is pretty simple to understand and troubleshoot if you know what you’re looking for.

Most of the problems with the ECS system are caused by a failure of three main components. The strut wiring cap, the strut itself or the ECS controller. Unfortunately too many people jump right to the controller being the issue without actually finding out the problem. When the sport/tour lights on the dash are blinking in your face, that means the ECS system has entered into an error state. If this occurs when you first start the car then it’s due to the initial self check test failing. Usually due to a communication issue with a strut. If the lights start flashing when you change modes then it can be a strut taking too long to respond or a controller issue. If the lights start flashing after driving or hitting a bump then this is most likely a wiring or strut issue. Follow this guide to track down and locate the root cause of the issue.

First let’s understand how the system works. Each strut has a small motor at the base of the strut piston. this mtor drives a gear that changes the size of the orifice on the strut, changing that orifice size changes the amount of dampening force the strut has. There are three different sized orifice modes SOFT/MEDIUM/HARD. On that gear there are also 2 micro switches (S1 & S2) that tell the computer the state the strut is in. So as the orifice gear turns it will hit the switches telling the computer its state and stopping the motor. Below is an example of the switch modes.

  • Soft = S1 closed / S2 open
  • Medium = S1 closed / S2 closed
  • Hard – S1 open / S2 closed

Each strut will have 5 wires going into it as seen in the image. The motor and switches have seperate grounds to prevent any interference. A very fragile plastic flex cable runs from the motor at the bottom of the strut piston to the top of the electrical connector. There are occasions where this connector breaks inside the strut of a circuit gets damaged in which case the strut needs to be replaced as the interworking of the strut are not repairable.


The signals from the strut go back to the ECS computer itself which has 2 user controllable modes TOUR/SPORT. Sport mode switches all of the struts into Hard dampening mode. Tour mode takes feedback from the car and adjusts the dampening depending on the condition present. The image here show the functions the computer will adjust to in Tour mode and how it stays in Hard dampening when in Sport mode.

ECS Function mode

The Front struts on the FWD and AWD are exactly the same including the dampening forces. The rears struts are the only difference but it’s only in regards to the strut length/stroke. The dampening is still the same on the rears also as seen in the below images


Strut Cap

The front strut caps are more susceptible to having issues than the rear. The fronts have to rotate with the steering so the constant movement of the wires can eventually break a wire in the strut cap plug. Another common cause of the wires to break is from people leaning over the towers where working on the car. Since the wires come straight out the top of the plug, the weight on the top of the plug can cause them to break. Start by removing the strut tower cap, disconnecting it from both end. Pull back the black rubber cap over the strut plug. Look for any broken wires. If you ran repair the broken wire then do that but usually the wire breaks right at the crimp to the connector, so your only option is to replace the strut cap and wiring. If you don’t find any broken wire then do a continuity test on each wire to be sure it’s not damaged anywhere else.

ECS Controller

99.9% of the time the ECS controller failure is due to the capacitors that were used inside the controller that after time have leaked out small amounts of acid that have broken the traces on the circuit board. The easiest way to tell is to remove the ECU controller from the rear right trunk access panel and open it up. You will either notice a fishy smell from the capacitors leaking or you will see a blackish fluid and possible burn marks on the circuit board. If you know how to work on electronics then you can repair the trace and replace the capacitors on the board following the guide on the wiki -> Replace ECU, ECS and Climate Control Capacitors

The ECS Controller and Caps are fairly easy to detect f there is an issue just by checking them visually or simple multimeter tests. Testing the struts themselves can be very difficult sinc you need to apply power to the motor and check each of the micro switches to ensure that they are functional. I decided the best option was to build a simple tool that would allow me to test each strut to ensure it was working properly without needing to be hooked up to the system. I also use this tool when I go to junk yards as I’m able to tell on the spot if a strut ECS is functional.

The tool is simple to wire following the diagram below. For the power souce, the ECS strut motor requires a 5v signal to power it. I ended up just using a 12v battery in the end and it works fine as long as I’m just doing short presses of the bottom. if you hold it down for a long time you may burn out the motor. Using a momentary button, you press it down and the motor spins, completing the circuit on each switch which lights up the leds. Just like the above of the switch modes, green = soft, green/red = medium and red = hard. I usually let it cycle though the modes a couple times to ensure it’s all working. If you hook it up and press the bottom and you don’t hear or see anything, then the motor may be locked up or an internal wire broken. If you press the button and only a single led lights up, then again a broken internal wire or a bad internal microswitch. Basically if any of the modes fail or it does nothing then the strut is garbage. I built this tool inside a small project enclosure box


Also need to note that when the system does fail it does not always lock the struts into hard mode as everyone has assumed for years. If an internal strut is not responding then the system can’t lock it into hard mode, so you could have struts locked into hard and some stuck in soft mode when makes for an interesting ride. It can only lock them into hard mode is something fails a test and the computer is still able to communicate with each strut. else you will be stuck with mixed mode struts. The system will also lock them into medium mode if it sees the steering sensor not responding.


Be sure to check out the ECS guide I created that goes into more advanced details about the system including the wiring diagrams and such -> ECS Guide