LL using CC switch

Someone refresh my memory on hooking line locks up to your cruise control switch please. At one time I had the information but it seems to have vanished.

LL using CC

This should help...

http://www.modularfords.com/forums/showthread.php?t=64240&highlight=cruise+control+buttons

I'll be doing the same thing in the Spring.

doesnt that disable the cruise control system?

94tbird said:

doesnt that disable the cruise control system?

Click to expand...

No it doesn't

Thanks guys. That's what I was looking for

So....wiring with a relay would look like this??? Or not? Easy guys....wiring just is not my deal. Neither is posting a diagram so open the attachment and let me know.

US-1 said:

So....wiring with a relay would look like this??? Or not? Easy guys....wiring just is not my deal. Neither is posting a diagram so open the attachment and let me know.

Click to expand...

No, the relay is there only to provide good current/voltage to the line locks. The cruise control "off" button provides the ground to trigger the relay - so there is only one wire connected form the cruise control to the relay (the "sense" or "on/off" enable of the relay).

So, you wire both 12V sides of the relay to a nice healthy 12V source (back of fuse box under hood with an in-line fuse will do the trick - does not need to be switched).

The ground that feeds the line locks comes from the chassis - just attach it to the frame somewhere.

The ground that feeds the "sense" (on/off of the relay) comes from the cruise control.

Now, if you want to retain your cruise control function using a switch - go see:
http://s197forum.com/forum/showpost.php?p=39561&postcount=91

It may also been in the MF thread, but again, the point here is to have the cruise control provide the "ground" only to the on/off of the relay not to sink current to hold the line locks... That way you don't pull too much through the cruise control wire...

Don't have a diagram handy, but you should see something like:
.....C
.....|

A__ \__ B

.....|
.....D

Don't take my A,B,C,D too literally (some will have their own A,B,C,D on the diagram), but in this diagram:
A = 12V directly from battery (through a fuse of course).
B = 12V to line lock (red wire on the line lock)
C = 12V from anywhere (can just wire to "A")
D = GND from cruise control (or toggle switch connected to cruise control if you retain that functionality).

Then ground the linelocks other wire (black) directly to the chassis.

Relays are just an electromechanical switch, so there is no polarity with A/B - its just a wire when it is enabled. The C/D polarity will depend on the relay - read the box...

That's very cool...I'm doing this for sure.

Got it! Thanks Mike!

Cekim,

Not trying to be a kill joy, but switching a common (in this case ground) is usually a bad idea. Electrically speaking. If you get a wire rub before your switch, and the ground wire actually goes to ground, your line locks come on. If you run the Hot straight to the relay, and switch the common, then all the relay needs to energize is a ground. And it wont care where that ground comes from, the switch, shorting to ground via a wire rub etc.

Switching the Hot will eliminate the possibility of that happening. If you get a wire rub on the hot side before it hits the switch, the hot side goes to ground and you blow a fuse, instead of completing the electrical path for the solenoid activation relay.

TexasKyle said:

Cekim,

Not trying to be a kill joy, but switching a common (in this case ground) is usually a bad idea. Electrically speaking. If you get a wire rub before your switch, and the ground wire actually goes to ground, your line locks come on. If you run the Hot straight to the relay, and switch the common, then all the relay needs to energize is a ground. And it wont care where that ground comes from, the switch, shorting to ground via a wire rub etc.

Switching the Hot will eliminate the possibility of that happening. If you get a wire rub on the hot side before it hits the switch, the hot side goes to ground and you blow a fuse, instead of completing the electrical path for the solenoid activation relay.

Click to expand...

No joy killled... In a perfect world, I'd switch hot too...

At issue here is using the cruise control button - admittedly, it has the risk you cite, but bottom line is it floats when it is open and grounds when you hit "off", so if this is what you want to use, then switching ground is the only option without replacing the switch on the steering wheel (or using a switch somewhere else).

If you are concerned about this, You can:
a. put the relay inside the car close to the steering column to reduce the amount of "unfused" ground wire at risk, but the result of the short isn't going to cause a current spike anywhere - it simply "completes the circuit" and activates the line locks...

b. put another toggle on the 12V side of the relay enable as a failsafe. With that off, a short to ground won't enable the line locks. Using the line locks would require toggling the 12V enable as well as the CC bypass switches. No chance of a misfire...

There is no catastrophic risk to line-locks stuck on, they don't activate your breaks - they only hold what pressure is there - that would not be good, but its not like it slams on the brakes at 80mph...

As with any wire, it should be adequately secured to prevent rubbing, pinch, etc... there are no moving parts here, so its just the rattle of the car...

So, the tradeoff does not seem all that severe...

Cars used positive chassis for decades with no real tragedies.

It is a risk and I am glad you brought it up for the benefit of “non-technical” people who want to try this mod. It should give them an even higher incentive to do a good job.

I would also recommend using a solenoid B+ arming switch as a safety. Even if it is under the hood and armed when you get to the track…

marcspaz said:

Cars used positive chassis for decades with no real tragedies.

Click to expand...

It isn't the polarity of the chassis, it is the fact that the 12V side is fused and a short from 12V to chassis ground creates a current spike that pops that fuse and breaks the circuit. So, it is the polarity of the switched wire relative to the chassis.

A short of the ground in this situation does not have a current spike, so no fuse pops, the line locks just enable as if you had pressed the button and stay that way.

So, electrically speaking it is less "risky" than a short from 12V to ground. Functionally speaking the "failure mode" is less graceful, but again, if you are concerned about that - just switch the 12V side as well with a toggle to "arm" it and then enable it with the CC switch.

No problem pointing out risks, but IMO, this isn't a big concern - you should always wire carefully both sides of the circuit carry the current.

No harm, no foul. Just throwing that out there.

Ok, i'm reviving this monster from the deep.

Question, how does the On and Off side of the cc switch function exactly? I just want to clear it up, before I make a few diagrams to help people out.

This is a guess without digging up wiring diagrams and tech articles, click the on and it trips the module to turn on the cc, but does that wire that hooks to the ON side of the cc switch stay hot while the cc is on? If so, then the OFF side must have power on one side of the switch until you push the OFF button and ground it to turn it off? I just need to figure this out, because if hitting the cruise ON switch energizes the wire on one side of the OFF switch until you push it to ground it, this wouild be very easy to setup for a LL with a safety switch to keep it from accidentally being activated. Let me know so I can make up the diagram. My car is back in the shop, so I can't go out with the multimeter to answer my own question. Thanks guys.

KIMMER said:

Ok, i'm reviving this monster from the deep.

Question, how does the On and Off side of the cc switch function exactly? I just want to clear it up, before I make a few diagrams to help people out.

Click to expand...

The CC button is a tri-state switch...

The CC switch shorts to ground for "off" (thus its use on the ground path for line-locks).

The "on" is a momentary switch - when hit it puts the PCM's CC in the "on" position until the "off" button is hit. Subsequent hits of "on" won't do anything....

This is where I am a bit fuzzy, I seem to recall that the "on" voltage (actually "impedance") did not just short to "12V" which is why people used the ground of the "off" instead of 12V of "on" (because "on" put something like 5V on the wire...)

I do recall that the diagrams showed it to be a multi-impedance switching circuit with "off" being 0-ohms to ground and "on" or not pressed being some other impedance (and thus some other non-zero voltage)...

Hope that helps, I don't have the diagrams in front of me here... If you need more, I can dig them up this weekend...

cekim said:

The CC button is a tri-state switch...

The CC switch shorts to ground for "off" (thus its use on the ground path for line-locks).

The "on" is a momentary switch - when hit it puts the PCM's CC in the "on" position until the "off" button is hit. Subsequent hits of "on" won't do anything....

This is where I am a bit fuzzy, I seem to recall that the "on" voltage (actually "impedance") did not just short to "12V" which is why people used the ground of the "off" instead of 12V of "on" (because "on" put something like 5V on the wire...)

I do recall that the diagrams showed it to be a multi-impedance switching circuit with "off" being 0-ohms to ground and "on" or not pressed being some other impedance (and thus some other non-zero voltage)...

Hope that helps, I don't have the diagrams in front of me here... If you need more, I can dig them up this weekend...

Click to expand...

Do you know the voltage that goes through the OFF side to ground it out? I take it that it is 12v on the off side when you ground it if people are using it to power a solenoid?

KIMMER said:

Do you know the voltage that goes through the OFF side to ground it out? I take it that it is 12v on the off side when you ground it if people are using it to power a solenoid?

Click to expand...

Not quite sure what you mean there?

When you press "off", there is a zero impedance (zero resistance) path to ground through the "on-off" wire...

That is, when "off" is pressed, that wire is effectively grounded to the chassis.... So, "0 volts" relative to the chassis...

The way it is being used is to "ground" a solenoid which has its 12v side hard-wired to 12V. So, 12V switch/sense side of the solenoid/relay to the battery full time and the ground wire of the switch/sense side of the solenoid/relay hooked to the "on-off" switch.

When the on-off switch "floats" (i.e. is not pressed), it prevents the relay/solenoid from sensing the "switch" voltage and it holds it "open" so the power circuit is not complete...

Just to complicate things, that assumes you have just cut out the PCM's CC input and left it hanging - dedicating the button to the line-locks...

If you want line-lock and cruise control to work - you put a switch in there to choose the relay ground or the PCM/CC path - but never both...

Ah, perfect sense now. Think I have a way to do it with a 3 way toggle so that no power back feeds the module that controls the CC when using the button to ground the solenoid. I'll draw it up and see what you think.

This look right for NOT retaining the CC? Of course if you wanted to retain the CC, you could do the 3 way toggle switch (SPDT) and hook up the other end of the tan w/orange stripe wire to it.