Hi guys, so basically I'm having the dreaded issue with the Active Handling, it started braking out of the blue at slow speeds or curves, thankfully not at high speeds, yet, so it's at the dealer and located an issue with the Suspension Control Module (GM 15808061), I thought I was OK as I had found it at gmpartsgiant.com along with the other supposedly faulty part, the Front Left Suspension Control Position Sensor (GM 89047642), however I received an email 24 hours later that mentioned the position sensor was discontinued with zero availability and the control module was back ordered with unknown ETA, wonderful, so now I need it ASAP and have had zero luck locating one that would ship fast, I found one but they would be shipping it in April 12-ish.


TL;Dr I can't locate a new Suspension Control Module (GM 15808061), so I was wondering if anyone knows where I could buy one or equivalent, thanks!

 

I googled the part number and even Walmart (yes you read that correctly) says it carries them.

 

They don't unfortunately, trust me I've tried, most places have it out of stock or on an unknown eta backorder.

 

OK, my second guess: How about one of those places that do repairs on circuit boards. I looked around and found https://circuitboardmedics.com/.

Don't know a thing about them or anyone in that business, but it might be worth the $time if you can't find the part.

 

Need to back this way up, since the F55 module has nothing to do with ABS active handing braking.

If car is braking out of the blue on its own, problem is either in the Yaw sensor, the steering column position sensor, or the EBCM module (which controls active handling). If you have problems with one of the Tire speed sensors in the wheel hubs (and correct size tires on the car), then it would be giving you DTC for this.

So low down is the big one in the mix is the steering wheel position sensor, which tell the EBCM (which controls active handling) if the car is aimed straight, or if its being turned in a corner. From here, Yaw sensor (below the radio) reads the amount of pitch angle and G's that the car is seeing, and EBCM uses this to determine if ABS needs to kick in to straighten the car back out (the reason that the ABS fires to brake some of the tires to straight the car back out). Also to point out, BCM and TC button come into the mix, since active handle will be more sensitive when in all nanies on mode, where as once the system is set up into comp mode, will allow the rear end to kick out more before Active handle steps back in.

So step one is to pull up BCM data with a Tech II, and make sure that the steering wheel sensor is working correctly/one of wires is not grounding out. The sensor should read O voltage with the wheel at dead center, voltage go negative and climbing with wheel turned all the way left, and then go back to zero with wheel straight again, then go positive voltage climbing with the wheel turned all the way to the right. This is done for a few wheel turned lock to lock, as well as telescoping the wheel out and back in at the same time to check for wiring problems as well. Hence on a high speed race course with the nannies still full on, not uncommon to go into a corner under hard breaking, and have Active handle kick in (some of the tires braking) to not make the corner. This is normal, and why the car is run in at least comp mode, to desensitize the active handing/allow the back end to step out more, before active handling kicks in to straight the car out of what is thinks you have lost control of the car. Myself, since I tend to skate the cars even more, will run the car in all off mode, so active handle is off and does not try to save what it may think I have the car out of control.

As for yaw sensor, since it also reading pitch angle of car as well as G forces, a little more harder to check with it still bolted in place, so will unbolt with it still connectors so can pitch the module in hand to check the angle sensor readings, as well as jolt the sensor side to side and front to back, to get it's G reading data readings as well.

Wheel speed sensors, that one is easy to check and just need to first spin the tires to see if they are giving readings, then double check the tire sizes of all 4 tires, since the car need to have the rear tires about 1.08" large in the rear than the fronts for the ABS module to see that the all 4 tires are moving at the same speed. Hence if tire sizes are wrong, will trip DTC/trip active handle since it think that the car is not tracking the ground all four corners correctly at the same time.

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As for F55 module (above the ECM),and again has nothing to do with active handling braking. Easy enough to go into F55 module to pull is readings (hell ride sensors can be pulled from BCM data as well).
Short bus, each ride height sensor should be reading 2.9 volts with car on level ground, and when you dance that corner of the car, should change the voltage reading of that senor. Shocks will through a DTC if there connector wires are not connect, and it voltage increases/decreases to the shock, in regards to the changing voltage of the ride height sensors for the most part. As for ride control button, it sends it signal to the BCM (again, easy to check in BCM data) and then BCM tells which mode the F55 should be in in the end. So BCM or f55 data, push/turn the ride selector button, and make sure that the module are changing from tour to sports mode.

So to sum it up, with the active handling locking up some of the tires in slow corners/not pushing the car hard enough to make the car think that you have lost control of it and it needs to kick in to save the car to get it back going straight, the problem is in the EBCM and it sensor, not the F55 module and its sensors isntead.
Again, F55 has nothing to do with the active handle system, but only the suspension ride control of the car (how it stiffens or weakens the dampering of the shocks alone).

 

Thank you so much for that! So sorry for the late reply, I will relay this to the dealership, so bizarre they can't pinpoint what causes this issue which has really been plaguing these cars for a long time now, very discouraging not to mention the predatory "suggested" fixes they always add with parts that are currently difficult to get a hold of due to supply issues.