ARC Wiring/sensor questions

Mercutio

SCCoA Member
I got sick of staring at the useless ARC plugs on my car, so as part of a "while I have the carpet out" kind of moment, I decided to actually delete the ARC wiring--all of it. So far so good, but...

Each of the front ARC plugs has a yellow wire w/black stripe. These wires run into the interior ahead of the glove box, but once inside, they actually split off and go back outside, with two new yellow wires w/black stripes. One of these runs to the ARC/EVO test plug on the back side of the front passenger side wheel arch. Can I remove that wire/plug with no ill effects?

The other yellow wire w/black stripe runs to this gray plug located on the back of the driver side front wheel arch. What is this plug?

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It has two other wires running to it, a black w/orange stripe, and orange (could be pink-ish, I guess). Can I pull the yellow/ black stripe wire from that plug as well and be rid of that wiring entirely?
 
Bump.

I got my EVTM today, so now I know that the above connector is C1066, and the orange/black wire runs to the soft & hard ride relays, and the orange wire connects the brake pressure switch to the suspension computer. But I'm still trying to figure out which wires I can delete, and which I can't.

Can I delete this plug entirely, along with the hard/soft ride relays? Do those affect or only respond to hard braking input?

Also, ignition power comes from the purple/orange wire out of C217 (yellow plug behind passenger kick panel) to the suspension computer. I assume the speed-sensitive steering system still needs this connection even if the adjustable suspension is deleted completely--is that correct?
 
Yes Yellow/Black is only for the ARC system. Brake pressure output, steering wheel output, which goes to ground in the ARC Control module (also ground for actuators).

Nothing else is connected so should have no problem removing the relays and plug.

As for Purple/Orange yes it would be easiest to just leave it alone, since on SC EVO system is built into the ARC system. Now if you wanted to go through the hassle could get a EVO controller and replace the ARC module with it.

On C217 all you need is Red and Brown wires, but I'd leave it alone unless your really anal about getting the ARC out.
 
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Thanks! Don't want to clutter up the thread, but this is for you.

I don't think I want to swap over to a standalone EVO controller, because I was under the impression the ARC computer also controls ABS, correct? Or am I mistaken on that one? Because I can't see anything relating to ABS in the EVTM's pinout diagram of the ARC computer connector (C-403).

My car is a 94, in case that matters for the above question.
 
I also meant to ask about the ARC/EVO test plug (C162). It now has only two wires in it, White/Purple and Gray/Red, both of which run to the ARC computer. The EVTM lists both as "Auto Shock Test Connector." Nothing in the EVTM mentions EVO testing--can I delete these two wires and the connector, or are they there to support the EVO system?
 
Yes, I physically traced the wires from the ARC/EVO test plug to the ARC/EVO computer in the trunk.

Will a regular OBD1 scan tool scan that plug, or do I need a specialized tool that probably no longer exists? I can't say I've ever actually heard of anyone testing the system.
 
Yeah, I just tried running the test with the OBD1/2 scan tool I normally use on that car. The connector fits, but I ran a KOEO test (your link doesn't say whether the engine needs to be running), and the tool was unable to read the system.

If this is a tool that nobody has/uses anymore, then I don't see the point of keeping the diagnostic capability. I'm sure dealerships are purged of EVO testers, but is that something a normal shop might have?
 
For 93 a test light is all that is needed and would assume the same for 94/95. Ford says a 194 or 161 blub for the light. Can also just jumper W/P to ground and watch the Firm Ride light just like any other code.

As for the ABS it is completely separate; it uses sensors dedicated to it only.
 
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I wanted to get the engine bay stuff wrapped up today (getting the ARC wires out of the harness required actually getting to the harness, which required removing the cowl and wipers). So to get that done without making a decision on the ARC/EVO test plug, I just de-pinned the plug, pulled the wires back to the trunk, coiled and zip-tied the wires, and re-pinned the test plug. If I decide to delete it later, it'll take 2 minutes.

Edit to add:

Bowes, does the test procedure you describe work for displaying EVO codes, or just ARC codes?
 
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Short answer; Yes it checks both.

If I'm reading it properly, if you remove all the ARC components like you are doing you will get all the code under normal operation--except for the EVO.

So the only codes you would care about is 6, 16 or 26. All of which tell you to check the EVO for continuity, and or Ohms 5-20. So honestly I would just remove the light from the dash and not even care about the EVO test.

The procedure are different for 89-93 and 94/95, but results would be the same. For you no need for test. If/when you have a EVO issue check the connector to the EVO if it and EVO are good check the capacitors in the Control Module.
 
Thanks again. My box o' removed wiring continues to grow.

Also, now I am actually considering whether it's worth to switch to a standalone EVO module in place of the ARC/EVO computer. Is the EVO module any smaller or lighter than the ARC/EVO computer? I've never even seen one, and can't find a picture.
 
One more ARC wiring question: O/R goes from the ARC computer to "Automatic Shock Control Module Illumination." DG/LG goes from the computer to "Firm Ride Indicator."

Which of these the firm ride light in the VMM? What's the other one?
 
I'm not seeing O/R in the ARC system, but DG/LG is the illumination circuit (P/O is the hot side and DG/LG is the switch ground controlled by the module).
 
I'm not seeing O/R in the ARC system, but DG/LG is the illumination circuit (P/O is the hot side and DG/LG is the switch ground controlled by the module).

Could be different based on year, but the 94 EVTM says pin 1, circuit 293 in the ARC computer is Orange/Red. Pin 15, circuit 419 is DG/LG, with the circuit functions described in my last post.
 
Giving a Pin Number helped, it just used when headlights are on, I would assume its a dimmer.
 
That makes sense--looks as if O/R (circuit 293) runs from the ARC computer to C217, and from there to C232. The dimmer switch also has an O/R wire on circuit 293 that runs to C232.

So dumb question, but why is the ARC computer tied to the dimer switch? I don't see an O/R wire or circuit 293 running to the VMM do dim the bulbs, so what else does the dimmer have to do with the ARC/EVO system?

I'm genuinely not understanding the purpose of this particular wire.
 
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