ARC issues,

T1Bird

Registered User
Having a hard to diagnose issue with my ARC system, shocks are 4 years old, brand new at the time, worked fine up to my track day on July 21st. What I do is set the mode to firm with the key on, undo the front actuators, then set it to auto and race, after that i set it back to firm do them up and drive home. Well I forgot to set it back to firm, and did the actuators up in auto and drove home listening to the rears clicking away. Well since then my firm ride light has not been able to go off.

I've Tried:
In auto mode, undo the front clips, set to firm, then hooking back up-did not fix
Pulling all 4 actuators, turning the key on in auto, seeing all of them physically move, but yet firm light stays on-no fix
Putting 4 new actuators on, same outcome.
WD40ing the actual pins in the shocks, seem to move free no problem.-no fix
Replaced ARC comp with one from 89 cougar 5spd, one from a 90 auto car, and then my 90 5 spd car, all have the same outcome firm light on.
Replaced both ARC moduals located on trunk deck tray, no fix
check both fuses #12 at drivers feet and "I" in engine bay with multimeter. no fix.

Any ideas on whats left I can check?
 
Here's what I think:-
If the firm ride light is always on (after replacing the ARC computer, the two relays next to it, and the four actuators), then either the firm/auto switch is defective (contacts are always open) or the ARC computer thinks that one of the conditions for switching from auto to firm is being met (e.g., the brake pressure switch at the proportioning block is defective and the contacts are shorted together).
 
Have you tried unplugging all the shocks, setting the switch to firm, then plugging in the front shocks, setting the switch to auto, then plugging the rears back in?

I think that might do it. If not, sorry. But I think that might get everything back in sync.
 
JD, where abouts is this switch, I took a look but am not sure which one is the switch, if I disconnected it Im wondering if that would show me the problem.

I have tried many times to disconnect all 4 motors and still the same outcome, the odd time it will work for 2 or 3 attemps switching between firm auto, but most of the time it stays in firm.
 
You can pull codes from that system. You might try pulling codes. Do you see the actuators changing when you key on? They should cycle through a self check process on key on power.
 
JD, where abouts is this switch, I took a look but am not sure which one is the switch, if I disconnected it Im wondering if that would show me the problem.
........................
I was referring to the switch next to the fog light switch on the center console. The switch contacts are open in the AUTO position and closed in the FIRM position. So unplugging the switch will have the same effect as moving it to the AUTO position, and will show you if the switch is causing your problem.
 
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K i just came in from messing around with it again, still the same outcome, i have all 4 actuators plugged in, but off of the shock towers, I have gone from actuator to actuator each turning the key of then to on position and they all turn once 90 degrees, then thats it, no clicking back at all.

How do I pull codes for the shocks?

I also tried a new auto/firm switch, no change
 
Ford instructions are specific to their tester. You'll need to test some things with a standard tester to see what to do.

Turn Ignition off
Ensure headlamps, parking lamps and autolamps are off.
Set shock selector switch to AUTO
Connect SUPER STAR II tester or equivalent onto the connector marked ARC/EVO located under the hood by the passenger side shock tower.
Turn the testor on and depress the test button to the test down position.
Do NOT move the shock select switch during test.
Start engine and perform the following steps while engine is running.
The following procedure must be initiated within 20 seconds after starting the engine.
Release Star Tester in the test mode to the hold mode, and back to the TEST mode within 5 seconds.
The ARC/EVO module will run through self-test procedure and record error codes in Star tester and also pulse out error codes to the firm ride lamp.
Note: the lamp will blink the same code two times.


There is a complete pinpoint test in www.Alldatadiy.com for my 93. I don't have time to type it up as it is quite complete.
 
Should be, that's what I have but haven't tried the arc yet. It just acts like the EEC when it gives the codes. I believe the button on the top right would be like the button it says to do after 20 second and press and release within 5 seconds. You do something like that with the tester to clear the EEC codes.
 
Here's are two documents taken from mn12performance.com which describe the ARC system and how to check for error codes using a jumper wire.
Note that it says to ground circuit 209 at pin 3 in the test connector, which according to the diagram should be pin 4.
In post #6 I mentioned, as an example, a defective brake pressure switch that is always closed. I'm not sure if the error codes will help in this case. You might have to either unplug the switch or unplug the ARC computer connector and check the resistance between the two wires that run to the brake switch.
 

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Well ill wait to get the code reader to see if I can pull any codes, that pin method to me is jibberish finding the pins etc.

I would still want to pull the connector for the ARC off the brake system, just not sure what one it is, here is a pic, is it in this location I have circled?
 

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So jackit up, undo the electrical connection, and if my firm light seems to disappear, thats the culprit im to understand?
 
Issue fixed!

It seems that from maybe icing down the motor all these years, the water dripping off the IC tubes falls right on the pressure switch with the ARC control, I jacked the car up and took off the connection, switched the key on, boom works fine. I took a better look at the connection and it was correded, i cleand the contacts, put some Di electric grease in there popped it back on and voila it works great!
 
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