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Check for trouble codes and take it from there. You need a FSM for trouble shouting problems like that.
Variable Effort Steering (VES) has erratic boost
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Unplug the four-pin potentiometer connector from the bottom of the steering column near the firewall (engine side). Problem gone forever in my car... just have full assist at all times. Much better than having scary steering through curves.
And you haven't experienced anything bad yet until it happens to you on ice or snow covered off ramp curve!!!
I give GM a 0 out of 10 for using a potentiometer on the steering column instead of an LVDT for this variable effort steering system.
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It was my understanding the OP did not want full assist on highways...
Figure it out before driving more...
I can't quite sort out what the problem is from the description, but stop driving it until you figure it out
This would be a good time to check out all the steering components anyway.
1. With the engine off, is there play in the steering wheel? If not, good. If yes, find it. If the steering wheel moves and the Pitman arm at the bottom of the steering box doesn't move, then you have a worn steering box, intermediate shaft, or steering column bushing/bearing.
2. If all that is okay and the Pitman arm moves, then raise the car (don't forget the jackstands) and check for play in the center link, idler arm, tie rod ends. If you can turn a wheel in and out and feel looseness before the other wheel moves, some or all of those things are worn, or the ball joints as well.
3. Grab the top and bottom of the tire and try to rock it in and out. Any movement likely means worn/misadjusted wheel bearings
4. Turn the wheels all the way to the left and then the right, and check for play in the linkage or ball joints.
5. Now, onto the variable effort steering. If the boost is suddenly increasing in curves, then the valve is at fault. It's supposed to give you full boost at idle and less as the car's speed increases. You can disconnect the electrical connector and the problem will go away.
If this kind of analysis is straightforward to you, great. If it sounds like a bit much, then bite the bullet for a diagnosis fee and take it to any Chevy, Buick, or Cadillac dealer and have them show you what they find. Don't risk lives with messed up steering
Good luck!
I can't quite sort out what the problem is from the description, but stop driving it until you figure it out
This would be a good time to check out all the steering components anyway.1. With the engine off, is there play in the steering wheel? If not, good. If yes, find it. If the steering wheel moves and the Pitman arm at the bottom of the steering box doesn't move, then you have a worn steering box, intermediate shaft, or steering column bushing/bearing.
2. If all that is okay and the Pitman arm moves, then raise the car (don't forget the jackstands) and check for play in the center link, idler arm, tie rod ends. If you can turn a wheel in and out and feel looseness before the other wheel moves, some or all of those things are worn, or the ball joints as well.
3. Grab the top and bottom of the tire and try to rock it in and out. Any movement likely means worn/misadjusted wheel bearings
4. Turn the wheels all the way to the left and then the right, and check for play in the linkage or ball joints.
5. Now, onto the variable effort steering. If the boost is suddenly increasing in curves, then the valve is at fault. It's supposed to give you full boost at idle and less as the car's speed increases. You can disconnect the electrical connector and the problem will go away.
If this kind of analysis is straightforward to you, great. If it sounds like a bit much, then bite the bullet for a diagnosis fee and take it to any Chevy, Buick, or Cadillac dealer and have them show you what they find. Don't risk lives with messed up steering
Good luck!
Thanks Northern-. If that goof in Post #5 had had a little better command of the technical nomenclature surrounding this issue then I bet everybody woulda' believed him more. hahahahahahaha
For HUF, as I posted I could tell absolutely no difference in either steering effort or response comparing unconnected to connected.
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That's what I predicted.
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Fwiw...
In the days of old, before the crash, this was discussed at length, so we are doomed to repeat history, having none...I heard it referred to as "Ghost Grab" and experienced it on the 1995 Roadmaster Limited wagon.
Try this, or ignore it...you have nothing to lose except perhaps the symptom you are experiencing. Buy a bunch of power steering fluid and a turkey baster. Get a recycled gallon jug and start siphoning out the power steering fluid. You will probably find out it looks like hell. Empty out as much as you can from the reservoir, fill up, run car and do it again. Keep on until the fluild you are removing looks like the fluid you are putting in.
These cars are approaching over 15 years old, fluids break down seals age, etc. If it does not solve the problem at least you'll have clean PS fluuid and you can say I'm crazy. If it works, as it did for me, do it again in 15 years and drink a toast to the forum that was.
Keep old cars and old men with old cars young...
Richard Snipes
4501 Safari in Jax, FL
In the days of old, before the crash, this was discussed at length, so we are doomed to repeat history, having none...I heard it referred to as "Ghost Grab" and experienced it on the 1995 Roadmaster Limited wagon.
Try this, or ignore it...you have nothing to lose except perhaps the symptom you are experiencing. Buy a bunch of power steering fluid and a turkey baster. Get a recycled gallon jug and start siphoning out the power steering fluid. You will probably find out it looks like hell. Empty out as much as you can from the reservoir, fill up, run car and do it again. Keep on until the fluild you are removing looks like the fluid you are putting in.
These cars are approaching over 15 years old, fluids break down seals age, etc. If it does not solve the problem at least you'll have clean PS fluuid and you can say I'm crazy. If it works, as it did for me, do it again in 15 years and drink a toast to the forum that was.
Keep old cars and old men with old cars young...
Richard Snipes
4501 Safari in Jax, FL
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Since I unplugged the connector 2 days ago, the problem has been eliminated. I still don't like the fact that I have a loose wire just hanging, but hey the problem is gone. I was thinking about cleaning the connector with some electrical cleaner then plugging it back up to see if that would stop it from malfunctioning.
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I have a theory....
My 94 RMW has this same symptom, sometimes worse than at other times. When making gradual turns at highway speeds, steering wheel suddenly jerks. I have to brace my steering hand against my knee to minimize lurching across the highway. I know I could disable the system, but I'm too stubborn to give up just yet.
Anyway, my theory is that the root cause of the problem is in the rotation sensor at the bottom of the steering column. That is, I think it gets dirty inside and at certain positions sends an inaccurate signal to the electronics. Kind of like static from a dirty radio volume control. These sensors are of course entirely obsolete and unobtainable from GM or other sources. What I did, is to actually buy an entire junkyard steering column, and throw away everything but the rotation sensor! I have been using electronic cleaner/lube on the sensor, but have yet to swap it into my car. We shall see what happens!
My 94 RMW has this same symptom, sometimes worse than at other times. When making gradual turns at highway speeds, steering wheel suddenly jerks. I have to brace my steering hand against my knee to minimize lurching across the highway. I know I could disable the system, but I'm too stubborn to give up just yet.
Anyway, my theory is that the root cause of the problem is in the rotation sensor at the bottom of the steering column. That is, I think it gets dirty inside and at certain positions sends an inaccurate signal to the electronics. Kind of like static from a dirty radio volume control. These sensors are of course entirely obsolete and unobtainable from GM or other sources. What I did, is to actually buy an entire junkyard steering column, and throw away everything but the rotation sensor! I have been using electronic cleaner/lube on the sensor, but have yet to swap it into my car. We shall see what happens!
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I had the "ghost grab" in my '96 BRW when I got it, and it turned out to be the potentiometer around the steering shaft. At the time, new ones were available from GM, and solved the problem.
Test the pot by disconnecting the plug, attaching an Ohm meter, rotate the wheel, and look for the reading to change smoothly. If it jumps around, the pot is bad.
I have heard that the VES valves on the PS pumps are now unobtanium. The last time I went junk yard diving, all cars with these valves had had them removed.
I had a -94 Fleetwood that I suspect the computer gave up on the VES, and set it to max boost all the time. By the way, this was the best driving car I ever had. The steering was accurate, with an excellent tactile feel.
On both these cars, I flushed out the old fluid and added the GM winter fluid, which is synthetic, and very expensive. Turned out to be worth it. GM PN 12345867. If you get a shrieking noise for a few seconds from your power steering pump on cold mornings, you need this stuff.
Test the pot by disconnecting the plug, attaching an Ohm meter, rotate the wheel, and look for the reading to change smoothly. If it jumps around, the pot is bad.
I have heard that the VES valves on the PS pumps are now unobtanium. The last time I went junk yard diving, all cars with these valves had had them removed.
I had a -94 Fleetwood that I suspect the computer gave up on the VES, and set it to max boost all the time. By the way, this was the best driving car I ever had. The steering was accurate, with an excellent tactile feel.
On both these cars, I flushed out the old fluid and added the GM winter fluid, which is synthetic, and very expensive. Turned out to be worth it. GM PN 12345867. If you get a shrieking noise for a few seconds from your power steering pump on cold mornings, you need this stuff.
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UPDATE: It's been almost a month and the problem hasn't returned (knocks on wood). So in my case, unplugging the connector solved the problem.
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Thanks for the update, that may be my next step.
I suctioned out 1/3 of a quart of fluid 3 times and my fluid is looking pretty clean. I haven't felt it since, but my symptoms were subtle and only when it was quite warm - so I will probably have to wait for summer to know for sure, or take a snowbird trip south to test it. cwm1
I suctioned out 1/3 of a quart of fluid 3 times and my fluid is looking pretty clean. I haven't felt it since, but my symptoms were subtle and only when it was quite warm - so I will probably have to wait for summer to know for sure, or take a snowbird trip south to test it. cwm1
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Where potentiometer connector located??
Have a 94 impala ss same problem while driving on the x-way and changing lanes.
Can anyone take a pic of this connector not able to locate any at the bottom of steering column near the firewall.
Thanks
Have a 94 impala ss same problem while driving on the x-way and changing lanes.
Can anyone take a pic of this connector not able to locate any at the bottom of steering column near the firewall.
Thanks
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35 Posts
Where is the potentiometer on a 94 impala ss??
Having same problem on expressway when changing lanes. There nothing on the colum shaft at the firewall. have a pic would be appreciated. Thanks
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Where is the connector?
Having same problem on a 94 impala ss when changing lanes on the expressway.
Not able to locate the connector. Thanks
Having same problem on a 94 impala ss when changing lanes on the expressway.
Not able to locate the connector. Thanks
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165 Posts
Your 94 Impala doesn't have this system. It was only installed on Roadmasters and Fleetwoods.
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