Need Help - Speed Sensitive Steering

jjklongisland

Registered User
OK, so my car is in the shop getting my clutch put in and for the last two months my steering no longer tightens up when at speed. It is extremely annoying and I hate the way the car handles like this. I think I educated myself in that the way the system works is that at a certain speed a sensor actuates the EVO valve and it basically turns off the power steering stopping the fluid from assisting.

What is the trouble shooting procedure. What do I check first. The plug is plugged in by the steering pump. I believe there may be a module on the rear package tray for this feature. Somehow I believe there is also wiring that comes from the strut tower and is integrated with the ride control??? why i dont know. How can I check if the EVO valve is getting the signal? Any help would be greatly appreciative.

I have heard that sometimes you have to replace the steering rack because there is also a valve in there???? I am so lost and need some direction.

thanks
 
Still nothing.... I would love to have a conversation with someone who knows how the system works. If someone would PM me I will reply with my cell... thanks
 
Check the plug at the EVO. On mine a few years ago I had that happen and found the insulation on the wires at the plug had pulled back exposing the copper wire and they were twisted shorting out. I redid the plug by coating the wires with RTV silicone to reinsulate them. No problem since.
 
ARC?

I thought we were debugging your steering :) I think you mean EVO...

The only time ARC and steering work together is when the steering wheel is turned at such a rapid rate as to signal for the auto ride system to tighten up the shocks. The wires on each shock are for the actuators, which are commanded by the ARC blackbox in the package tray. ARC on or off....shocks firm or soft, the steering system proper isn't affected.
 
ARC?

I thought we were debugging your steering :) I think you mean EVO...

The only time ARC and steering work together is when the steering wheel is turned at such a rapid rate as to signal for the auto ride system to tighten up the shocks. The wires on each shock are for the actuators, which are commanded by the ARC blackbox in the package tray. ARC on or off....shocks firm or soft, the steering system proper isn't affected.

As per your linked post
..I replaced the ARC module and...ahhhh...all is good! Steering's great again. Feels like my shocks may have been "stuck" in firm mode despite being in soft mode (even when the firm light was working) because, with the replacement module, the normal ride is much smoother. For a while, I'd thought it was odd that it was so difficult to feel the difference, compared to my last SC.
Thanks to all of you who put in your 2 cents. It was worth more than 2 cents to me."

I read through it too fast. I didnt realize his ride control wasnt working either. Mine lights up and still works. My only problem is the steering.

Shock Absorber Electronic Steering Sensor Input
An optical shock absorber electronic steering sensor (photo-cell) has the following characteristics:
• It is mounted on the steering column tube.
• It is used to establish the straight-ahead position of the steering wheel.
• Once the shock absorber electronic steering sensor has determined this position, it can measure the steering wheel turning angles and then calculate the lateral acceleration that results.
• If the calculated acceleration is greater than predetermined values, the shock damping is switched to the firm level of control. This input is not used until the vehicle speed is above 19 km / h (12 mph).
• Once activated, the shocks will remain firm an additional seven seconds after the vehicle's speed and/or steering wheel position drops below the parameter levels.

So does anybody have an EVO for sale? Pardon my stupidy but is the EVO in the plug itself or the part between the pump and the plug???
 
been looking for an EVO myself and wasn't able to locate one new or used. If you find a line on something let me know. Thanks!
 
I have had an intermittent EVO system failure, in which it quickly jumps to full assist and then back. Not much fun. :) The on-off nature of it leads me to believe that it's electrical in nature, but I have been too busy to track it down so far.

I do have a spare EVO valve, and I can say that it is quite simple in design. The high pressure feed comes in the end, is restricted by a pintle valve to the desired amount of pressure, and exits through a ring fitting on the side of the valve. The electrical component of the EVO itself is just one simple solenoid coil. The only ways it could go bad are a short from bad insulation (or gettin soaked somehow), or a broken wire inside (which seems unlikely). You can do a quick ohm check across the terminals of the coil. You can also open up the EVO valve from the backside and clean it out in case the pintle is stuck. I don't think there is an easy way to get at the innards of the coil, though. That would be a job for a rebuilder who has spares available.

With all that in mind, I think the two most likely culprits (by far) are the wiring to and from the system components, and aged components (electrolytic capacitors?) inside the ARC module itself.

Does anyone have pics of an open ARC module for reference? It's got a case much like an EEC case, but I haven't cracked one open yet.
 
P.S. - On the early model SCs, the EVO control is integrated with the ARC box. At some point, LX cars got EVO as well. I think it was 1993 or 1994. Those cars had a stand-alone EVO controller. I am not sure if the late model SCs had a separate EVO controller or if it was still integrated with the ARC for those two years.
 
I have an extra arc module I can test to see but the car has been down for a while due to the trans. I also believe I am getting an error code 17 on the arc system but it's been so long i could be wrong on the code. If it ends up being the ARC module i will tear the bad one apart and post pics might be a bit though.
 
It's been my experience over the years that intermittent problems on machines that vibrate to any degree are caused by connectors, plugs, sockets, etc. As the cars age the metal pins corrode enough to cause a break and make connection. You could disconnect all of the plugs, spray them with contact or brake parts cleaner, and then reapply dielectric before reassembly. It might help some of these problems. A bad ground connection is something else to look at. It's amazing what a bad ground on a car can screw up. A lot of the relays have partially burnt points by now, too. At work we use a relay in the switching power supply of our older motor controllers and I'm constantly replacing them for customers. And don't forget my bare twisted wire scenario above.
I checked the EVTM book and there is indeed a direct connection between the two. The steering sensor feeds the ARC and the steering control is located in the ARC module. If anybody needs an ARC module, I have several. Send me the type code and I'll see if I've got one.
 
So I changed the EVO and still no bueno... I am going to change the ARC next... crossing my fingers... Hopefully thins weekend
 
When I had issues with my steering it was a bad Capacitor on the ARC module. I'd suggest as opposed to just swapping parts open the module up and look at the board.
 
When I had issues with my steering it was a bad Capacitor on the ARC module. I'd suggest as opposed to just swapping parts open the module up and look at the board.

Good info... Hopefully thats what it is. I will see this weekend. thanks
 
My ARC Module seems to be bad as well (similar power steering issues, shocks will not consistently go into Firm Mode, and I hear a clicking noise coming from the truck occasionally).

Stupid Question: How do I remove the shelf in the truck to access the ARC Module? Also, where can I get a new ARC Module?
 
The rear package tray is pinned on one end and hinged on the other. Check the driver side for the twist-release pin.

Try the 'Want To Buy' forum to see if someone has one for sale.
 
Thanks. Just pulled the ARC Module and broke it apart. Sure enough, it appears one, maybe two, capacitors are burned. Roadtrip to Radio Shack!
 
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