Resistor Bypass for F55 Magnetic Ride Control
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Cadillac Seville / Cadillac Eldorado Forum Discussion, Resistor Bypass for F55 Magnetic Ride Control in Past Cadillac Vehicle Discussion; Ok in short in F55 equipped cars the suspension module MUST see a 1-3 OHM resistance from each strut/shock in ...
  1. #1
    1BadCadSTS's Avatar
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    Resistor Bypass for F55 Magnetic Ride Control

    Ok in short in F55 equipped cars the suspension module MUST see a 1-3 OHM resistance from each strut/shock in order to complete the module check of the suspension system. Anything above or below this and the strut is considered failed an throws a code. I have had and can show the strut fail on an 03 STS where the fluid leaked INTO the air bladder NOT around the bottom of the strut per typical GM check and threw NO code. Only found out after removing it compressing it (it still had recoil but not nearly as much as the new one) and heard a gurgling noise. Flipped the air nozle on the shock down and compressed it and sure enough fluid came running out. Wasn't fun chasing a clunk noise for 3 months when the strut kept testing good and I didn't want to pay the money for a strut for my mothers car and be wrong but after everything else was checked or replaced it was the only thing left.. I personally love the system and would never bypass it, the strut on the 03 was replaced with the proper GM F55 shock but I know some either cannot afford it or justify the expense of paying almost the cars worth into a suspension repair.

    Anywho on to the bypass...

    I have completed this on a 06+ DTS Performance and two 07+ Eskys all with F55. A normal 1/4 or 1/2 watt resistor will work for 1 yes 1 start up and then will fry as it cannot handle the current cycled through it been there and tired it that's how I know.

    HOWEVER

    http://www.radioshack.com/product/in...ductId=2062290

    Those can in fact handle the current.

    You will need 2 PER STRUT/SHOCK wire them together and 1 end to the 2 wire factory car wiring and the other to the other wire.

    That is it, yup it is that simple, from there you can install whatever aftermarket passive strut you want be it Arnott, Monroe, Strutmaster etc....

    I keep a set of those resistors in my box in the event I ever need to confirm a strut/shock code is from the strut/shock and not a wiring related issue along with a set of 4.7k resistors.

    Any questions don't hesitate to ask. I can take a video showing the bypass working on my 05 STS and 03 STS if needed.

    Mods may want to sticky this one.

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  3. #2
    JimD is offline Cadillac Owners Connoisseur
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    Re: Resistor Bypass for F55 Magneic Ride Control Cadillacs

    Quote Originally Posted by 1BadCadSTS View Post
    Ok in short in F55 equipped cars the suspension module MUST see a 1-3 OHM resistance from each strut/shock in order to complete the module check of the suspension system. Anything above or below this and the strut is considered failed an throws a code.
    Constructing a 2 Ohm resistor using two 1 Ohm resistors at 10 Watts is a brute force method of imitating an F55 damper.

    That obviously is one method and I could have done the same thing (using 10 Ohm resistors) with my F45 system. But I chose to do some testing and some math to arrive at an elegant "fix" that used a 1/2 Watt resistor. A 1/2 Watt resistor is much easier to deal with.

    Anyway! If you are interested in arriving at an equally elegant fix for the F55 system, I can walk you through the testing and then given the values I am looking for, I will do the math and suggest a 1/2W resistor value for testing. Any resistor value I suggest will be a readily available Radio Shack item.

    If I had an F55 equipped car in my driveway I would already have done the testing and the math.

    You will need an ammeter and know how to interpret the display.

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    1BadCadSTS's Avatar
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    Tried a 1/4 and 1/2 watt. It burned them both up after simply turning on the key. Those suckers i posted work. The escalade I tested them with was over 2 years ago. It had 119k on it and now had 238k (travels ALOT) and is an 08 platnium resistors still working fine.

    As I said I'm completely uninterested in changing any of my failed components with anything otter than oem f55 equipment. Love the system especially the selectable mode on my 05.

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    Law Guy is offline Cadillac Owners Member
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    Re: Resistor Bypass for F55 Magneic Ride Control Cadillacs

    Hey guys,

    I am about to try this out, and I have a question for 1BadCad..

    This may seem like an obvious question, but should the two 1 ohm resistors be hooked up in serial or parallel?

    Not sure if I have to place them side-by-side and twist the ends together, or if I have to attach them in a chain, or sorts.

    Sorry for the newb question, but I am not sure if the Ohms are added together when they are in a row, or in parallel.

    Thanks for the advice. Gonna order some from Radio Shack now.

    My local electronics store had similar ones.. I tried them... had to use four per strut as they were 5W.. and they did work for a few minutes, but when I restarted the car... I got the message again.

    I am definitely going to order these from Radio Shack!

    Thanks,

    LG
    (08 CTS Sedan & O8 Escalade Platinum)

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    Re: Resistor Bypass for F55 Magneic Ride Control Cadillacs

    Two 1 Ohm resistors placed side by side and twisted together form a parallel resistor of 1/2 Ohm. Two 1 Ohm resistors in series form a 2 Ohm resistor. FWIW, Radio Shack and car audio installation shops have several values of 5, 10, and 20 Watt wirewound ceramic resistors with nice, big leads to work with.

    The F55 struts and shocks have no solenoids or moving parts other than the internal piston and rod - they use a variable 12 VDC voltage/current feed to vary the magnetic field around the ferrous fluid.

    Notice the sentence in this article - concerning the late 2002 STS as being the first Lord/DELPHI test mule.

    http://mutualhosting.com/~lordfulfil...oad/PB7138.pdf

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    TTT for basscatt

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    Re: Resistor Bypass for F55 Magneic Ride Control Cadillacs

    Quote Originally Posted by 1BadCadSTS View Post
    TTT for basscatt
    ----------------------
    thanks

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    Np mayne

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    KrahsSRXCaddy is offline Cadillac Owners Member
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    Re: Resistor Bypass for F55 Magneic Ride Control Cadillacs

    1BadCad what message were you getting on DTC for this fix. Was it 'Speed Limited to 80 mph' or the Servive suspension message?

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    stoveguyy is offline Cadillac Owners Connoisseur
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    Re: Resistor Bypass for F55 Magneic Ride Control Cadillacs

    how does stabiltrak work? thought the computer selectively stiffened shocks and applies brakes to control body roll and skid? so a now passive strut does nothing. only the brake portion of the antiskid system works?

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    1BadCadSTS's Avatar
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    Quote Originally Posted by KrahsSRXCaddy
    1BadCad what message were you getting on DTC for this fix. Was it 'Speed Limited to 80 mph' or the Servive suspension message?
    No message the struts were blown. We replaced with Monroe shocks spec for a Yukon Denali and placed the resistors to eliminate the service suspension system.

    ----------

    Quote Originally Posted by stoveguyy
    how does stabiltrak work? thought the computer selectively stiffened shocks and applies brakes to control body roll and skid? so a now passive strut does nothing. only the brake portion of the antiskid system works?
    With the bypass it really doesn't work to the full extent of oem. It only has control of the brakes after switching to a passive suspension system.

  13. #12
    stoveguyy is offline Cadillac Owners Connoisseur
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    Removing f55 stuff on 05-06 cars seems odd due to money issues.

  14. #13
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    Re: Resistor Bypass for F55 Magneic Ride Control Cadillacs

    If you can't afford the correct OEM equipment necessary to keep your Cadillac a Cadillac, go trade for a Toyota!
    .........just sayin.

    ----------


  15. #14
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    Quote Originally Posted by Caddydrummer67
    If you can't afford the correct OEM equipment necessary to keep your Cadillac a Cadillac, go trade for a Toyota! .........just sayin. ----------
    Ok... I have to ask, how much is can't afford?
    What does a MRC strut replacement cost?
    I know it's expensive, but you guys are making me think that it's BRAIN SURGERY money!

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    Re: Resistor Bypass for F55 Magneic Ride Control Cadillacs

    Caddydrummer67, The question on the resistors for the first gen SRX has been moved to the SRX forums.

    BlueAngel#07, For the 2002.5 - 2003 STS with F55 the front struts can go for around $750 - $900 each. Rear shocks a bit less. Right now, RockAuto has OEM F55 struts for $553 each, 4 left in stock. (What is the year of your Performance "DTS" ?)

    People plunk down $4600 to buy a sophisticated used car that originally sold for $56,000+ and then go orbital when they find out just how much it costs to correctly maintain it.

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