Help, unusual steering/ARC problem

Norm-L

SCCoA Member
I have a 95 SC 5-speed with 32,000 miles. Today a new problem arose. The car has been sitting for 3 weeks, on stands for the last week while I detailed the suspension and chassis. When I fired it up, the steering felt like it had tight spots. I then realized they weren't tight spots. With a neutral steering wheel, all is fine. As I add load by turning the wheel gently, the steering pulses. If I hold light effort on the wheel, it has a very steady pulse, about one/second. The pulse gets stronger with increased effort.
I drove it. After about 2.5 miles, it was fine. After another half mile, I parked it. When I restarted the car, the pulse was back. Again, it went away after 2.5 miles. As soon as the pulse went away, I stopped in the road, shut the car off, and restarted it. The pulse was back.
More testing...I started the car in the driveway (with the steering pulsing) and waited. After about 10 minutes (more than it would have taken to drive the 2.5 slow miles), it was still pulsing. Apparently not time related. I then drove it and, in about 2.5 miles, the pulse went away.
During this testing, I also noticed that the ARC was not working. The light would NOT come on under any circumstances including using the switch. As soon as the pulsing stops, the ARC works again.
This time, I drove it another 5 miles trouble free. When I got home, I shut it off, restarted it, and it was NOT pulsing and the ARC was fine. I don't know what will happen the next time I try.
Is anyone familiar with this problem? The dealer is willing to take $95 to diagnose it, but my SC is in showroom perfect condition inside, outside and underneath. I don't want to leave it in the hands of a mechanic I don't know. I seem to get my vehicles damaged everytime I have to leave them somewhere for work that I can't do myself.
I'd appreciate any help I can get. Thanks.
 
you didn't mention if you checked the power steering fluid level. start there. Power steering hoses can soak up water (say if you were spraying things off) which can cause odd steering until the water separates from the fluid.

Now if you feel it could be something with the ARC system due to the behaviors, about all you can do is check all the connections. There is a connector on the power steering pump. There is a connector on the steering column. Then connectors on each shock tower and the connector on the module in the trunk. Usually if the system is having problems, it will flash the firm ride light at you to indicate a problem. If the firm ride light is not flashing at you, but it seems to be acting up, I'm not sure what it could be.

Maybe someone else has had this happen and has a fix.
 
I think your ARC computer, which includes the variable-assist power steering, is acting up or losing power. Check the connections at the appropriate fuse/s and at the large connector on the ARC computer. Unplug the connector on the EVO valve and verify that the pulsation in the steering stops (You will have full power assist with the EVO valve unplugged).
 
Yeah, the first thing I checked was the fluid. It was to the full mark and the fluid looked like new (not dark, cloudy or milky). The car never sees rain and I never wash it with a hose, and lives in a climate controlled garage, so moisture is not likely (though not impossible). There isn't a single leak on the entire car so it shouldn't be that. I did check the connection on the EVO and it is fine. I've never seen the firm light flashing. It just doesn't come on, at all, until the pulsing stops.
I haven't tried unplugging the EVO connector to see if the pulsing stops. I couldn't find a definitive answer as to whether the EVO would default to wide open or closed, so I hadn't wanted to take the chance. Thanks for that info. I'll try unplugging it and see what it tells me.
Thanks, both of you, for your input. I'll let you know what happens. Something tells me I'll be hunting for an ARC controller...
 
My 94 SC has around 250k miles on it and until about 7 months ago, I never had any P/S issues (I've had it since it was new). However, when spiraling up/down a cloverleaf ramp on/off an interstate to a perpendicular road, I have noticed a "twitch" in the steering. I don't know if this is what you are referring to as a pulse or not. That behavior has been in my vehicle to some degree for as long as I can remember.

If you have done any recent p/s searches in this forum recently you have certainly seen the fits I have had recently with p/s pumps, and leaks around the EVO o-rings. Even with those things straightened out for now, I still have the "twitch" on cloverleaf ramps. I suspect it has to do with the angle the wheels are turned in relation to the speed I am traveling at.

Best Regards,

Ted
 
The pulsing I feel is constant for about 2.5 miles until it clears up, regardless of speed or direction of turn. It even acts this way when the car isn't moving. It makes the car somewhat difficult to drive because as you steer, the steering effort oscillates between very easy to very stiff every second or less as the steering wheel is turning. Someone following me through a corner may actually see the body of my car rocking side-to-side as though I'm sawing at the wheel (or someone's getting busy in my back seat). If the wheel is turned, but I am not applying any force to the wheel, it doesn't pulse. It only does it when there is some effort applied. I've worked on cars for some 26 years and I've never felt anything like it.
Btw, I do remember your steering woes in the forum.
 
I forgot to mention one small detail. If I'm parked, with the engine running, I turn the wheel a little bit with a couple of fingers, and hold it there, you can see the wheel turning back and forth about 5 degrees, against my fingers.
 
I'd guess that something was bent/pinched/torn/dinged/twisted when it was let down off the stands.

Might be time to get back underneath it (carefully) and do a close inspection - clean it off well to make sure nothing bad is hiding under road grime, etc.
 
It sounds like it's almost certainly an issue with the ARC/EVO computer or wiring. Any chance you can get your hands on a known-good unit to swap it out for testing?
 
I forgot to mention one small detail. If I'm parked, with the engine running, I turn the wheel a little bit with a couple of fingers, and hold it there, you can see the wheel turning back and forth about 5 degrees, against my fingers.

Disconnect the harness connector from the valve that is mounted on the power steering line, up near the pump. That should cause you to have full assist at all times. See if the behavior changes. If the behavior/problem goes away, then there is a problem with the orifice valve and/or the wiring to it, and/or the control system for it.
 
Now that I'm all done with the All-Ford car show at John Force's shop, I'm going to really dig into this problem. My first SC, which I sold several years ago, is still in this general area. I may be able to track it down. Maybe he'll let me borrow his control unit to help me troubleshoot...after I try unplugging the EVO connector. I am leaning toward the ARC control unit being the problem because of the concurrent ARC failure.
At least the problem is no longer intermittent. The pulsing no longer stops on it's own.
 
I just unplugged the EVO connector and, as predicted, the steering defaulted to easy with no pulsing. The question is, did the pulsing stop because the EVO couldn't do it without power, or because the "bad signal" from the ARC couldn't get to it? I guess a spare ARC would go a long way in answering that question.
I also noticed, when I disconnected the EVO, that the connector rotates around the EVO. The EVO isn't loose. Just it's connector. Is it supposed to be like that?
 
It is perfectly normal for the EVO actuator connector to rotate. The resistance between the two terminals of the actuator should be between 5 and 20 ohms. You can also check for a short between the wires that run from the ARC module to the actuator after unplugging the large connector at the module.
Have you checked whether the ARC is working correctly since disconnecting the actuator?
 
I did check and the ARC was NOT working when the EVO connector was unplugged.

Then I would leave the EVO alone for now. You need to test the ARC system by shorting two pins in the ARC diagnostics connector located at the driver's side shock tower and then reading the code that the firm ride indicator flashes.
 

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Well, here's the scoop. I tried doing the test at the data link connector. No luck. Under no circumstances could I make the firm light do anything. It doesn't even come on when I turn the ignition on. I checked and double checked and I'm positive that I had good connections and did the test right.
So next, I pulled out the service manual and followed the pinpoint test. If you follow the test here were the results:
A1 - No, couldn't quick test
A2 - Yes, continuity
A3 - Yes, 2.75 ohms
A4 - No, 40.9 ohms
A5 - Yes, battery voltage
A8 - Yes, power at shock fuse
A9 - (didn't make sense to me)
A10 - Yes, no resistance "replace control module"
A11 - No, switch ok
A12 - No, infinite resistance "replace control module"

I stopped there.

When I tested the EVO, the resistance was 38 ohms most of the time, but sometimes was very inconsistant.
Could I actually need to replace both, the EVO and ARC control unit?
Should I just start with the ARC unit?
 
These A1 - A12 test results don't correspond to the tests in the service manuals for the 1989-1993 cars, which is all I have. I had suggested running the ARC tests to find a defective sensor or actuator or a short in a sensor, actuator, or the wiring. You could disconnect some of the components in the ARC and VAPS (variable assist power steering) and then try to run the tests. It might be easier to just try a new ARC module, though I don't know if a faulty component can damage it.
The EVO resistance should be consistent because you are measuring the resistance of a coil. If the contacts are clean you will need a new one.
 
After I had no success with the quick test at the datalink, I disconnected the EVO. I tried the test again and still didn't get a code. It should have resulted in an open-circuit code. Since 2 of the pinpoint test results said to replace the ARC box, I will try that first...and the EVO, I guess.
Do you know what symptoms are expected when the EVO resistance is to high? Is the EVO hard to find? Do you know if the SC's EVO crosses over to the LX or any other models of Fords? I don't expect it's something carried by the parts store chains.
There is an inconsistency in the manual regarding the datalink. It says to use #3 for the jumper and refers to it as 290(w/p), but the connector diagram shows #3 as unused and #4 as 290(w/p). The connector has no terminal in the #3 slot.
Btw, when I had tested to EVO, at one point it read 41 ohms for about 5 seconds, then it started to climb, slowly at first and then it sped up and reached 800 ohms. It slowly dropped back down to 100 before I disconnected the meter and tried again. This repeated on the next try and then never did it again. I can't explain that one.
Thanks again,
Norm
 
Update

I found a flaw in my EVO test. There was a problem with one of leads I used with my ohm meter. Upon retesting the EVO, the resistance is a very normal 13 ohms. Whew, that's one oily mess I shouldn't have to make. The leads I used for the rest of the testing are fine.
I'll see if the steering/ARC problem is fixed when I get the control module.
 
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