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Xoutpost server transfer and maintenance is occurring.... |
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#11
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1988 325is (purchased new) sold 2004 X5 3.0 2005 X3 2.5 2008 X5 3.0 (new to me) |
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#12
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Quote:
Do you mean pins 1 and 2 at the SVT module connector in the glovebox?
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2008 X3 (E83-LCI) 3.0si M-Sport 2004 X5 (E53-LCI) 4.4i M-Sport 1994 318i (E30-LCI) race car - sold |
#13
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Quote:
I saw it in the linked photo, thanks. I guess testing it probably requires removal. I'll crawl under this weekend to see if I can get hands on it.
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2008 X3 (E83-LCI) 3.0si M-Sport 2004 X5 (E53-LCI) 4.4i M-Sport 1994 318i (E30-LCI) race car - sold |
#14
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Quote:
In normal operation, that makes sense to me. But what if that valve #5 is completely closed or clogged? I wonder if that valve handles just a control bypass in parallel with the rack or full flow from the pump?
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2008 X3 (E83-LCI) 3.0si M-Sport 2004 X5 (E53-LCI) 4.4i M-Sport 1994 318i (E30-LCI) race car - sold |
#15
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Yes. You should be able to measure some sort of impedance. Then if not, make sure you have continuity on the harness at least. It's just a solenoid like for a transmission. This thing runs on a PWM signal based upon the calculated duty cycle from the SVT module. There is a functional description that explains this that I would have to find. I'd have to figure out if the solenoid is normally open or closed. If open, it would make sense that it would divert all line pressure back to the reservoir and no power assist. Not sure exactly...
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2003 BMW X5 3.0i -- MT5, 3.64s final gears, H&R lowering springs, K-Mac bushing kit 2007 BMW X3 3.0Si -- MT6 |
#16
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So I did some more reading and found the hydraulic architecture for the servotronic PS.
The servo is normally open when no power is supplied to it. Therefore, this would be considered minimum support from the PS pump and divert the majority of assist back to the reservoir (expansion tank). Supplying the Servotronic valve with power This leads me to believe there is a fault on the SVT and its effectively turning off the powersteering, aka, no steering force by means of all the DSC issues you mentioned on the previous post.
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2003 BMW X5 3.0i -- MT5, 3.64s final gears, H&R lowering springs, K-Mac bushing kit 2007 BMW X3 3.0Si -- MT6 |
#17
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Where is the pump in that diagram? If steering assist is at minimum (for highway speed) with loss of the servotronic then you would think if that were the problem it wouldn't have cut the assist enough to almost miss the off-ramp?
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1988 325is (purchased new) sold 2004 X5 3.0 2005 X3 2.5 2008 X5 3.0 (new to me) |
#18
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Haha, OK I see the pump. My mistake.
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1988 325is (purchased new) sold 2004 X5 3.0 2005 X3 2.5 2008 X5 3.0 (new to me) |
#19
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From what the technical description is saying, it would seem when the servo is off that nearly all pressure is diverted back to the reservoir, thus, making it high effort at the steering wheel.
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2003 BMW X5 3.0i -- MT5, 3.64s final gears, H&R lowering springs, K-Mac bushing kit 2007 BMW X3 3.0Si -- MT6 |
#20
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Sorry for my slow follow-up. With the holidays I haven't had time to even pull the glovebox apart for the multi-meter test just yet. I did read over on the M5board that a bad servotronic valve almost always throws a code. Otherwise, the valve seems easy enough to replace with just removal of the drivers front wheel and a couple of torx bolts to free it from the rack (assuming they don't strip). They also said 4 ohms is good but even a few ohms different is bad, FWIW. So hoping to finally test the valve resistance soon.
Since I've still got no relevant code, though, it does seem at the moment to more likely be an actual pump or rack issue in my case. Not wanting to deal with the rack itself, I can get a 2007 pump (since our X3 is 1/2008 production, but I think the pumps changed in 3/2008) and will probably see if that helps after confirming the correct valve resistance. Hopefully no pump difference for servotronic - I'm assuming just the rack with servotroinic valve would be specified differently with versus without the option. Next I just need to figure out how to get at the pump - hopefully from the top. If the valve resistance seems okay and the pump replacement doesn't help, then I'll of course swap out the valve, code or no code, before contemplating replacement of the whole rack. R&R of that rack does not look like any fun! More soon...
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2008 X3 (E83-LCI) 3.0si M-Sport 2004 X5 (E53-LCI) 4.4i M-Sport 1994 318i (E30-LCI) race car - sold Last edited by o2bad455; 12-28-2021 at 04:02 AM. |
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