ECS Suspension stuck in stiffest setting

Hello everyone, my name is Cristian.

I have a 1991 3000GT SL with some fun problems, most of which are detailed in another post. That post is mostly related to engine problems so I thought I’d separate this issue into a new thread.

My ECS light quit working a while back. When I first got the car I could switch between Tour and Sport (which didn’t feel like it did anything at all btw), but after a few days of driving (car had been sitting for a while before I bought it) only the Sport light would show. When I pressed the ECS button, I could switch between the Sport and no light.

So right now my suspension seems to be stuck in its most stiff setting, this makes my 25 mile commute to and from work quite bumpy.

I checked the connections to the tops of the struts and they all seemed sound, no debris/corrosion found. I unplugged my ECS computer out of fear that I was frying it worse than it already might be or something, so now I have no Sort or Tour light, and I’m still stuck in the stiffest setting.

Anyone know of any common points of failure in the ECS system, besides the ECS computer caps going bad? I just replaced the capacitors in my ECU and tested them afterward, they were all in perfect condition so I would think that since the ECS was built at the same time it would likely be in the same condition. (could be totally wrong, I know).

Thanks for any advice you guys might be able to provide!

Maybe the tour light bulb has gone?
Could be caps but everyone replaces these because someone on facebook said that this is the cure for everything, but quite often, the capacitors are only part of the problem. Maybe I’m unlucky but I usually find that only 10% of failures are simple capacitor faults and the rest are other components that require a little bit of fault finding.
Another common problem is broken wires to the struts but this would cause both tour and sport lights to flash.

Its possible its just the bulb. Like I said though I kind of didn’t feel any difference in the ride before the tour light had kicked the bucket, then again maybe I’m just overestimating the power of 30 year old suspension engineering lol. I’ll look up the wiring schematics and see if I can probe anything.

There’s some easy things you can to confirm whether the system is working or not, if you don’t trust the lights or your ability to feel the difference between the two modes. With the key in the “on”/“run” position, but without the engine running, you can test switching between sport and tour.

  • Listen near the strut caps while someone toggles the button. You should be able to hear the motors in the struts switching modes. You can listen to each of the 4 struts to confirm if all/any are cycling through positions correctly.
  • Find a sturdy spot to press down and bounce the suspension of the car while someone toggles the button. You should feel an obvious difference in how firm the suspension is. This can be done in front and rear.

Unfortunately, some of your explanation seems inconsistent/incomplete, so it’s not clear what you are experiencing right now:

  • You say you could never feel the difference between sport/tour, but now that it’s stuck in “sport”, you complain that the ride is too bumpy? Does this mean that previously it was stuck in “tour” mode because it was less bumpy all the time regardless of the mode you selected?
  • What exactly is the current condition of the sport/tour lights. Is the “sport” light on solid all the time, even if you push the ECS button? Does it ever flash repeatedly on its own?

Your “tour” light being burned out makes things tougher, because you can’t tell whether it should be on or not. If it truly is stuck in “sport” mode (with “tour” light off), then it could be a problem with the switch itself, or wiring/connectors between the switch and controller.

I believe there’s also a possibility for the controller to fail in a way that both “sport” and “tour” lights are always solidly on, but you can’t tell if that’s the case with the bulb burned out.

The “normal” failure mode when the controller is functioning correctly, but detects a problem with a strut/sensor, is that both “sport” and “tour” lights will flash continuously.

If you don’t have it already, download the service manual: Tech - Manuals! Service, Technical , Reference | 3SX Performance Home Page

Vol 1. has all the info you need.

  • Page 33B-11 (777 of the PDF) starts the section describing how to read fault codes.
  • Page 33B-5 (771 of the PDF) starts the section of how to diagnose various problems.

BTW - If you don’t notice the difference between sport and tour modes, then either:

  • You drive on very smooth roads.
  • You are very imperceptive changes in suspension stiffness.
  • Something is wrong with your struts or ECS system.

The difference is quite obvious to me in my car when toggling the ECS on a road with bumps.

I’m from Rochester NY, our roads around here are pathetic lol.

A little clarification on what I meant in my initial post: When I first got the car I was able to switch between Tour and Sport mode, but I nor a few friends could actually feel any difference in how it felt going down a bumpy road. I believe it was stuck in Sport mode at all times regardless of which mode I had selected.

A little while later the tour light quit on me, meaning I could toggle between having the Sport light on (solid, no flashing), or no light on. I have not experienced any flashing of either the Sport or Tour Lights.

Does the ECS computer itself throw codes that you read from its harness? Or would it be thrown via CEL and be read through the OBD 1 Port?

Also, would toggling the ECS button having the key in the “ON” position but engine not running cause the suspension caps to react? I’m just thinking it might be difficult to hear them actuate with the engine running is all.

Edit: I’m rereading the manual and if I understand correctly I should be looking at pins 3 and 12 on the OBD 1 connection for checking ECS codes?

I think I already answered all of your questions in a previous comment:

  • See service manual for instructions on how to read/diagnose ECS fault codes (I included a link and page numbers).
  • Yes, you can switch ECS modes without the engine running. That 's what I suggested. I tested my ECS this way during my pre-purchase inspection of my car. You can actually hear the ECS motors from inside the car if you listen closely, but better to listen near each strut to identify if any are not working. The bounce test of the struts when switching modes is also very obviously different if working properly.
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That appears to be correct:

NOTE: You will likely need to use an analog voltmeter. People have had trouble getting consistent/clear readings from digital voltmeters.

I have successfully read a CEL with my digital voltmeter but yeah, I can see what you mean by the potential to misread, some of the voltage spikes are so quick that you can barely even read them since the sample rate is too low.

I’ll give this stuff a try, thanks for the help.


Hooked up multimeter to pins 3 and 12 and measured voltage, I now know that I most certainly do need an analog voltmeter for this task, but also I read a whole bunch of long pulses and then I think a few short ones, but I’m not sure how many of either.

As per service manual this reading would make some sense;
Fail Safe = All ECS controls stop and Normal shock absorber dampening force fixed at HARD
Indicator Pattern; 6 long followed by 1-4 short indicating which strut is bad.

Also I removed the interior access panels for the rear struts and popped the hood, turned key to on position (engine still off) and pressed the ECS button on my dash over and over. Each press I would hear a slight buzz sound, coming only from the rear struts. I had someone else listen as well while I sat there and pressed the button and they determined that the front struts were making zero noise.

In any case, service manual says damping force changeover actuator defective would be the diagnosis. Sounds expensive to me…

It’s pretty common for the wires on top of the front struts to get fatigued an break internally (because the connector on top of the strut rotates as you steer the front wheels). That’s the most likely cause of your front struts not working. You should be able to test those wires with your meter. It may be an intermittent open circuit issue depending on how the wires are bent.