F355 Shock Motor Manual Settings?

Hi guys, My suspension light is on and I have done all the checks on the forum removed and checked all 4 motors and driven them both ways with the B and C terminals, cleaned and lubricated the gears and removed checked and cleaned ecu but Light is perminantly on and doesent go past the self test. Speedo works fine and there are no other electrical issues. Suspension was working fine but the light was comming on after a restart and then not going off.

Is there a fuse or relay that controlls the system?

I would like to know where I can set the damper controll rods to manually as I need to use my car this weekend for a charity event, the damper controll rods are all free and I have rotated all 4 to the full anti-clockwise position, thinking this may be a good setting, the car drives like its got oval wheels and jumps all over the road?

Any advice to where I can set the dampers to or any other areas to check untill I can get it on a diagnostic would be much appreciated...

Many thanks in advance

Jeremy...

 

You already did a lot ...
When you drove the motors directly on their connector, have you checked that the Hall effect sensors (2 per motor) deliver a square signal while the motor is turning. If 1 sensor over the 8 is bad you will get the light. The minimum set-up to check each sensor is to connect the pin D to a +5V source, and each sensor output (pins E & F) to the same +5V source through a resistor (a few kOhm). Then with the motor turning slowly, you should see, with a simple voltmeter, the voltage on the Hall sensors outputs swinging between +5V and 0V.

Other possibilities are the acceleration sensors at the front of the car which may be bad or experienced a connexion problem ...

If you want to use the car with the ECU non operative, I would suggest you set the 4 shocks at # 60° from the softest position. That is close enough to the error setting (actually 55°) when the ECU is able to drive each motor but not to adjust ths suspension according to the driving conditions (see page F26 of the WSM)

 

Thank You eric, I have a portable scope so I will have a look at the readings tomorrow, I havent got a workshop manual yet, just ebayed one, which direction is soft on the damper rods then, full range stop to stop is aprox 90deg so would half way be good drivable setting?

Thanks for your advice

 

If you can PM me your phone number, I can help you preset the dampers. I have run dyno sheets on the stock shocks many times.


Jay

 

Most likely a bad actuator. I had the light, and could not find anything wrong with any of the actuators, and went through all the checks. I ended up swapping the left rear (just decided to start there) and "bingo" I have never had a return of the suspension light...so I found the bad one.

 

Great if you have a portable scope ... don't forget the pull-up resistors on the sensors output.
I agree with Hugh, it is sometimes not so easy to identify a bad actuator. I had the case on my car. One actuator was starting to seize and the only difference with the others is that it was just a bit slow.
I don't know which direction is soft on the damper but it shouldn't be that difficult to find it. According to the WSM the difference is discernable only in the expansion characteristic of the shock. Compression is very much less dependent of the setting. Between full soft and full stiff you should feel the difference.
If you have any doubt, I would say that 45° is OK. That is close to the soft setting of the ECU.

 

Mmm checked shock motors and all appear to be ok? no real variations on the readings that worry me, The system doesent appear to self test and operate the motors and the light never flickers or changes during the self test period or after?

I have checked the supply voltages to the motor plugs and only get 5v on the d terminals which looks right, any Ideas why it wouldent attempt to run the self test, do these Suspension ecu units fail often?

 

Does anyone know where the two acceleration sensors are fitted and the best way to access them...?

 

They are both behind the front bumper, in the middle of the front face of the car. You have to remove the bumper.
I doubt that, even if they are at fault, it would prevent the ECU to complete the self test and actuate each motor to CW end-stop and to CCW end-stop.

 

Thanks Eric, I thought no one on here has ever mentioned them, Its looking like the Suspension ecu has poss gone down?

Can they be got at from the fog lamp access plates under the front so i can check the wire plugs etc...?

 

From the fog lamp access plates? I don't think so. May be from the front undertray but I am not sure. I never tried to access them and can't remember if they are visible with the tray removed.

Have you checked that both connectors are well connected to the ECU? Mainly connector B which is dedicated to the shocks motors. Have you open the ECU to look at any sign of failure? It can probably fail but the symptoms look strange.

 

Yes I have had the ECU out twice and looked over it with a magnifing glass and cleaned with contact cleaner, I have got a wireing diagram but it uses so many junctions its untrue, i cant see where there is any connection with the door contact switches, Im a citroen tech and had lots of experiance with activia but this system is weird?