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1999 Park Avenue Ultra - Magnasteer


The00Dustin
11-19-2008, 09:02 PM
I previously posted about a problem I have had with steering since a Rack & Pinion replacement:
http://www.automotiveforums.com/vbulletin/showthread.php?t=922252
It was determined that my car has magnasteer, but not necessarily whether or not that was likely the culprit. The problem hasn't surfaced again since then. That said, I am still wary of the whole mess, so I wanted to find out if it was possible to disable magnasteer. Assuming it is, I wanted to find out whether or not doing so would be safe. I don't want to do this just for fun, but I figure it might be good to have a plan should the problem come back and persist. Sure, I might find out that it isn't the Magnasteer at that point, but I wouldn't be any worse off. Any input?

HotZ28
11-21-2008, 09:49 PM
I don’t think disconnecting the magnasteer controller would help reveal the problem, however it would make steering control less predictable and therefore unsafe. Have you had a dealer look at this? Some magnasteer systems can be programmed with a lap-top to increase/decrease steering effort. If this were a pump problem, it likely would be more consistent. Have you had your upper strut bearings inspected?

BNaylor
11-22-2008, 09:25 AM
:confused:

If you disconnect the Magnasteer system which means removing the voltage and current (hi/lo) to the MSVP actuator at the rack and pinion assembly wouldn't that make steering more difficult? IMO the steering will be hard or difficult at all speeds, the primary concern being at low speeds.

The Magnasteer system is controlled by the electronic brake and traction control module (EBTCM) which is the same module that controls ABS braking and traction control. It uses the wheel sensors to properly maintain variable effort steering which is easy at low speed or stopped and firmer or more resistance at higher speeds for better road feel and control.

The00Dustin
11-22-2008, 06:34 PM
I thought maybe the power steering would function as normal in the even that the Magnasteer failed (or was disabled), but it sounds like that is not the case, so I'm glad I asked. I haven't taken it to a dealer; I talked to a shop that does diagnosing and they said they didn't think it would have any codes stored, but they could try to diagnose it. I figured they wouldn't find anything anyway, seeing as how the initial problem cleared up after a couple weeks and now only happens once at random in a blue moon.

Regarding the EBTCM, since I bought this car, the ABS and Traction lights have always come on when driving in slush, and one winter they wouldn't go out between trips, presumably because it was so cold whatever caused it was frozen in the causing it position. This never happened on wet roads, though, just slushy ones. After an accident, they stayed on permanently, and the repair shop repaired a wire somewhere and the problem didn't come up even in slush the following winter. At that point, I assumed that this break in the wire was the culprit. Over the last year, though, starting in Spring or Summer, they started coming on at random and pretty much any time it would have been nice for the system to work (stopping on sand, taking out around a corner on sand, panic braking). Earlier this fall, I removed, cleaned, and reconnected a body ground that look like it might connect to the front passenger wheel speed sensor. This was coincidental, though, I was trying to deal with another problem that seemed likely to be caused by a bad ground. Both problems seemed to clear up, but I think the ABS and Traction lights have come on once since then. What gets me is this started with the new rack (as in on the drive from the shop after rack installation), but unfortunately, it's hard telling whether that really has anything to do with it.

82Stang
11-24-2008, 08:06 PM
Was reading through your complaint. The ground you were cleaning was probably the little metal bracket that holds the plug for the wheel speed sensor? It is mounted on the brake dust shield just above and behind the front axle. You could try cleaning the plug/connection to see if dirt and debris are getting in there or at the teeth grooves in the axle, which are read by the sensors. But the other end of this bracket goes directly into the wheel bearing/hub assy. It's a sealed unit so it shouldn't be unattached. If the ABS and traction control lights have come on, my experience with this problem was much like that on our 99PA and it was the hub assy, which has the wheel speed sensor built into it. It's not a real hard job to do if your handy. Could be the issue with your passenger front hub.

Thought this might be your issue with the warning lights illuminating.

BNaylor
11-25-2008, 06:55 AM
Best thing to do without guessing or assuming is get it scanned with an ABS capable scan tool. With ABS scan tool you can check wheel sensor comparative output to determine which wheel sensor is bad and see if any chassis/ABS diagnostic trouble codes (DTC) are stored in history. Best one to use is a GM Tech 2.

Also, often overlooked is a defective EBTCM module in addition to the hub wheel sensors or wiring. Classic symptoms is when an ABS or traction control fault occurs it may cause issues with the Magnasteer. Loss of or erratic steering when turning mainly to the left.

The00Dustin
11-25-2008, 05:46 PM
The hub bearing assemblies have both been replaced twice, and the ABS/Traction light behavior has not changed relative to these replacements. The ground I cleaned had three or four wires going to it, it was connected to the wheel wheel on the front passenger side back under something (but easy enough to disconnect and reconnect without removing anything).
Regarding the steering problem, it has erratic and loss of steering are words that could be used in conjunction to descride what happens, however, it has happened turning right as many times as it has happened turning left. I had a shop check for stored codes once because of the ABS and Traction lights; they told me there were no stored codes. However, I really don't know if they used an ABS capable scan tool (one would assume they surely did).

82Stang
11-25-2008, 09:54 PM
The hub bearing assemblies have both been replaced twice, and the ABS/Traction light behavior has not changed relative to these replacements. The ground I cleaned had three or four wires going to it, it was connected to the wheel wheel on the front passenger side back under something (but easy enough to disconnect and reconnect without removing anything).
Regarding the steering problem, it has erratic and loss of steering are words that could be used in conjunction to descride what happens, however, it has happened turning right as many times as it has happened turning left. I had a shop check for stored codes once because of the ABS and Traction lights; they told me there were no stored codes. However, I really don't know if they used an ABS capable scan tool (one would assume they surely did).

Does this rack have a PSPS (power steering pressure switch)?

Another Buick I had, did have issues with steering response. Just wondering if this might pertain to that?

BNaylor
11-26-2008, 08:03 AM
I had a shop check for stored codes once because of the ABS and Traction lights; they told me there were no stored codes. However, I really don't know if they used an ABS capable scan tool (one would assume they surely did).

You would assume the shop has a high end full function scan tool with ABS capability but that isn't always the case. The best scan tool to use is the GM Tech 2 which is dealer service. Based on your repetitive issues I would not rule out the EBTCM module. The only other possibility is the rack and pinion installed was defective. Was it an OE GM or aftermarket?

Does this rack have a PSPS (power steering pressure switch)?

There is no power steering pressure switch. It is EBTCM to the MSVP actuator at the rack and pinion.

The00Dustin
11-28-2008, 09:50 AM
You would assume the shop has a high end full function scan tool with ABS capability but that isn't always the case. The best scan tool to use is the GM Tech 2 which is dealer service. Based on your repetitive issues I would not rule out the EBTCM module. The only other possibility is the rack and pinion installed was defective. Was it an OE GM or aftermarket?
The rack was aftermarket. It had a 6 month warranty, but that has probably long since expired by now. When it did it the first day, the shop indicated that air in the fluid would do that with a new rack, and they had driven it and it stopped doing it, so they thought they had worked said air out. They said drive it for a couple weeks and let them know if it was still doing it. By the time two weeks was up it had quit and didn't do it for a couple months, then it only did it once on two separate individual occassions a couple of months apart. I talked to them at this time thinking it might still be under warranty, but they said they thought it could be the power steering, so they didn't want to replace it and find out it wasn't defective and warranty replaceable (however, at this point, they certainly didn't think it was air in the fluid anymore). Assuming it is the EBTCM, could it be a bad ground somewhere, or does the behavior more likely indicate a bad module? Assuming it is the rack, considering the fact that it has never prevented me from putting the car where I want it, would it be OK to leave it, or is it likely to get worse or seize up? Also, incidentally, it is possible that the only reason it has never prevented me from putting the car where I want it is because it has only happened at intersections, (which means either I was or had been braking to turn onto another road/parking lot, though it has definitely happened when my foot isn't on the brake after said braking).

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