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Rear Shock Problem (Mag Ride)


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I have had very few problems with my 2006 Performance Sedan... But now I have one.

The rear shocks seem to be locked up...
In other words, you can grab the body at the rear wheel opening and you can't pick up the body at all.
And of course if you push down on the fender, it doesn't move either.
I have never had one do anything like this before...

I did get under it and looked at the shocks... they DO NOT appear to be leaking.

The ride is about like a one ton truck with 10 ply tires aired up to about 60psi.
There is no give ... up or down... in the rear of the car.
It's almost like it is on a solid axle with no springs at all.

The front has normal up and down give to it as I push down on it.

Any ideas are welcome before I put new shocks on it.

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is your rear end riding high?

I am not too familiar with the newer setup but I would not think that both shocks would lock up. But I will say that if one is locked up to get it fixed asap because it will be very rough on the suspension components

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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is your rear end riding high?

I am not too familiar with the newer setup but I would not think that both shocks would lock up. But I will say that if one is locked up to get it fixed asap because it will be very rough on the suspension components

Ride height is normal...

"BOTH" of the rear shocks are locked up.

The front is normal.

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I suggest getting shocks and struts at the same time. If you have new rear shocks, the difference will highlight how much difference 160,000 miles makes in the damping of the struts.

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-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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That is weird. The only way I could picture shocks locking up is if the vehicle has sat for an extended period of time. But I suppose anything is possible. Is there anything electrical to the shocks? If so see if there may be any codes present

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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That is weird. The only way I could picture shocks locking up is if the vehicle has sat for an extended period of time. But I suppose anything is possible. Is there anything electrical to the shocks? If so see if there may be any codes present

It doesn't sit much... LOL

Yes, the shocks and struts are all MAG RIDE, so there is electrical connectors at all four of the shocks and struts.

There are no messages on the DIC...

I would have thought there would be a message, but there isn't.

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I am assuming that the mag ride uses sensors to open and close the valves in the shocks. I wonder if it is possible that something is making the valves stay closed. It just seems to coincidental that both would be locked up

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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Anything that would be part of the system would throw a code that would light up a warning light.

The mag ride stiffens the shocks but does not lock them.

I can understand an old shock locking up because of some debris getting in the piston or a valve. But two, at the same time, smacks of jack damage or some such. Are they both perfectly straight when you look at them on a lift? Are you sure that it's the shocks that are locked up?

I would verify that the stabilizer bar and links are OK and nothing is loose back there that could lock up one or both sides of the rear suspension.

But, this is Texas Jim, a really serious problem solver. Anything I can think of, I'm sure that he has already looked at.

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-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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Anything that would be part of the system would throw a code that would light up a warning light.

The mag ride stiffens the shocks but does not lock them.

I can understand an old shock locking up because of some debris getting in the piston or a valve. But two, at the same time, smacks of jack damage or some such. Are they both perfectly straight when you look at them on a lift? Are you sure that it's the shocks that are locked up?

I would verify that the stabilizer bar and links are OK and nothing is loose back there that could lock up one or both sides of the rear suspension.

But, this is Texas Jim, a really serious problem solver. Anything I can think of, I'm sure that he has already looked at.

I checked the rear stabilizer bar and all the attaching points along with giving a good visual of everything else I could see.

It all looks OK.

Nothing seems to be loose or disconnected or out of place.

It has not been on a lift in the last few months.

The shocks do not appear to be leaking... just normal road film on them... no fresh oil on the shocks.

It started suddenly... one day it was normal... they next day it was like riding in a truck... LOL

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I would get it on a lift ASAP and determine for sure exactly what is going on there.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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I agree on his diagnostics. No doubt, but this is confusing. The only 2 ways that it should ride like a rock would be both shocks maxed out, or seized up. Clearly they are not maxed out by the normal ride height, but should not be seized up either considering it being a DD

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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I'm pretty certain that the M/R fluid stiffens as magnetism is applied, so it appears that voltage is being applied to the magnets in higher amounts than normal. Disconnect the electrical connectors from the shocks and see if that helps. Since this is occuring while sitting, you may see a small additional load on the battery.

Ultimately, I'd say the ride computer lost control of the voltage going to the rear shocks, I seriously doubt that this is a mechanical issue, internal to the shocks or otherwise. The fact that both failed simultaneously should be proof enough of that.

Never underestimate the amount of a persons greed.

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Oh, and BTW, new shocks won't help. These suckers won't wear out unless they leak. No valves to fail either.

Never underestimate the amount of a persons greed.

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Oh, and BTW, new shocks won't help. These suckers won't wear out unless they leak. No valves to fail either.

THAT is good news. I wasn't looking forward to replacing mine, even in the mists of time.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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that is what I was thinking. Something is closing the valves too much causing the shocks to be extremely stiff. Likely a glitch somewhere.

I was actually wondering if resetting the battery may help

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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It appears that something is telling the shocks to go to the absolute stiffest setting, possibly beyond. Before throwing a pair of shocks at the problem (which would be horribly expensive), it may make sense to have a Cadillac dealer take a look at it and then weigh the options.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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Or, Bruce with his high-end laptop-based OBD scanner.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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I shouldn't have written that there aren't ANY valves in these shocks. They must have the typical valves that control the bound/rebound action, but I don't believe they are electronically controlled. I still maintain that the MR fluid is responsible for the task of stiffening the shocks during "spirited" driving or at speed.

I'd also try doing a system reset with battery disconnect as rockfangd suggested.

Never underestimate the amount of a persons greed.

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I left the battery disconnected all night... about 15 hours.

That didn't help.... drove it a little bit ago and it's still the same way.

I am beginning to wonder if it is the airbag system that is aired up too tight... but it is not setting up high in the rear.

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Does tire droop when u jack up rear? I see there is a $70 fe1 strut and a $250 fe1 strut and a $500 fe3 strut for 06. Something about awd strut vs non-awd strut cars.

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And that's why I suggested removing the electrical connectors from the rear shocks. Unless you are sitting on a huge magnet or fault line, I can't see another reason for the fluid to stiffen. Regardless, it sounds like it's time to call a dealership to see if they ever heard of this issue before. But before I'd buy shocks, I'd have an old one in my hand that is still locked up tight, and preferably a new one to compare it with.

Never underestimate the amount of a persons greed.

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Does tire droop when u jack up rear? I see there is a $70 fe1 strut and a $250 fe1 strut and a $500 fe3 strut for 06. Something about awd strut vs non-awd strut cars.

Mine is FE3....

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