FX3 upgrade from 1990 to 1992

[sevensixers]

I upgraded my fx3 shocks and control module from 1990 to 1992 setup. I have brand new shocks and a used 1992 control module. I keep getting fault codes 14, 31, 32, 33? I have removed the actuators to verify operation and they do work when the ignition is turned on, so they are trying to find the end stops. I checked that the shock gear is 5mm higher than the mounting ring on top of the shocks. The shock gears rotate freely with no binding. I tried swapping actuators around and no change. I?ve tried to clear the faults by grounding the C pin on the ALDL plug. Does anyone have any ideas of what else to try ? I thought it would be a direct swap with no issues, but I should have known better !!! Any help to get these faults cleared would be greatly appreciated !!! Thanks gang !!!

[-=Jeff=-]

Here are the errors.

14 = Right Front time out
31 = Left Front out of position
32 = Right Front out of position
33 = Left Rear out of position


Looks like the right rear works. Are the gears tight on the shocks? i have heard that could cause an issue. I have also had issues with the set height, how do you know that the shock gear is in the actuator?

[secondchance]

On my car, a 94, I was tripping code for front. Upon careful examination, I noticed OEM set up has rubber bushing between the top of the shock to underside of the steel bracket and another rubber bushing on top of the bracket to metal plate below metal cup. The lower rubber bushings had collapsed due to age resulting in the entire assembly being pushed up and the shock pinions were too high binding inside the actuator. Been awhile but I think I replaced lower bushing (under the bracket) with a new polyurethane version but kept OEM rubber bushing because polyurethane would raise the cup too high. Shop manual section 3G-20, figure 3 illustrates top of the metal cup to top of shock pinion to be 4.5 mm. Excessive deviation can either bind the mechanism (more than 4.5 mm) or pinion not engaging the planetary gear in the actuator (less than 4.5 mm).
As for the rear, I would make sure the shock gear (pinion) is good and actuator is functioning properly.
One more thing, at times rotation of shock gear are bit stiff and may require light lubrication to encourage easier rotation to avoid triggering codes.

[RSLyrick]

Hey,

I had a quick look at the FSM for in detail description of the DTCs.

"DTC(s) 14, 21, ARE STORED IN THE SELECTIVE RIDE CONTROL
(SRC) MODULE SENSES THAT THE CORRESPONDING ELECTRICAL
ACTUATOR IS MOVING TOO SLOWLY OR NOT RECEIVING THE
CORRECT FEEDBACK SIGNAL"

"DTC(s) 31, 32, 33 OR 34 ARE STORED IF THE SELECTIVE RIDE
CONTROL (SRC) MODULE SENSES THAT THE CORRESPONDING
ELECTRICAL ACTUATOR HAS NOT FOUND THE END STOP
POSITION ON THE SHOCK ABSORBER DURING INITIALIZATION"

The principle of the FX3 system is to adjust the actuator while sensing its position to ensure that the "instruction / shock setting" sent to the actuator has been correctly applied.

DTC 14 seems like the FX3 control system doesn't receive the feedback value at all or that the actuator is not reacting quick enough to the instruction (the feedback values being read out but the actuator actually didn't really have the time to reach its final position, leading of course to an error). Same issue with the DTC32 of the EGR system...

You should refer first to the 3G-9 diagnostic diagramm in the FSM.

DTC 31, 32, 33.

You confirmed that the shock actuators are moving freely.

You should refer first to the 3G-14 diagnostic diagramm in the FSM.

Additionnal info :

When installing new shocks it is mandatory to re-use the position of the actuator used after removing the old shocks (that's what's written in the FSM) :

"Actuator onto cup assembly retainer.
? Use position noted during removal"

My guess is that if you do not reinstall the actuator in its original position, you create some kind of "mechanical offset". What the FX3 think is 0° is actually maybe 5° it didn't reinstall the actuator as it was. It will try to set the shock to 60° upon start up (standard procedure), leading to read back 65° from the feedback signal.

This is just a supposition. If the actuator gear wheel allows you to connect it in every possible position when reinstalling the shocks, this is a really bad design.

They should have made the gear in a way that it's only possible to connect it in a single position. I'm curious to know about how it looks like. In the FSM, the selector gear looks perfectly symetrical allowing it to be connected in every possible way to the actuator...That would explain why they state in the FSM "Use position noted during removal"....Maybe other member can comment on that.

[sevensixers]

First off, I want to thank you for the help. I obviously underestimated the complexity of FX3 system. I did not check the gear height of the old shocks when I removed them. Unfortunately, I got rid of them so I cannot check the old height measurements. I put the new gears at roughly 5.0mm height from the top of the mounting ring. I will try different heights of the gear and see if that helps. I will also go through the procedures in the FSM. I will keep you all posted on my progress. Thank you all so very much !