'02 Chrysler Sebring LX Cruise Control

Hello,
I'm a college student who is planning on developing an aftermarker cruise control system as a final project for my bachelor of engineering
degree.
I'm wondering if there is a way to interface the car's cruise control system (to be able to modify the cruise speed). Does anyone have any input or ideas?
Thanks, Bryan
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Hello,
I'm a college student who is planning on developing an aftermarket cruise control system as a final project for my bachelor of engineering degree.
I'm wondering if there is a way to interface the car's cruise control system (to be able to modify the cruise speed). Does anyone have any input or ideas?
Thanks, Bryan
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snipped-for-privacy@gmail.com wrote:

The cruise control speed is incremented and decremented by two switches in the steering wheel - you can tap into their signals in the harness under the steering column - keep reading to find out how to use them for altering the cruise control speed. All cruise control commands are done thru two wires going thru the clock spring.
The following will be crystal clear if you get the schematics for the No. 1 Clock Spring out of the FSM - go to a dealer and ask if they'll let you look at their FSM - they might even photocopy the page for you if you ask nicely. Or - for the duration of your project, buy a one year's subscription to www.alldata.com for $25 ($14 for renewal after first year) using a valid VIN for your Sebring - that will give you on-line access to, among other things that may prove valuable, *all* of the schematics right out of the FSM. Do not go out and buy a Haynes manual - their schematics are not necesarily for your specific car - that's why they label them "TYPICAL" - you might as well try to use a roadmap showing roads between NY City and Pittsburgh to drive from LA to Seattle.
The clock spring system acts like an A-to-D converter.The PCM forces a fixed current thru the loop of the two clock spring wires - one of the wires is a return. The other wire has resistors of the different values on the distal end (in the steering wheel). The cruise control switches connect their particular resistor to the return wire. With the fixed current provided by the PCM, the resistnace value forces a certain voltage value back to the PCM's A/D converter which it corretcly interprets as a contact closure of the corresponding switch, and then takes the appropriate action on the cruise control system.
So - simply unhook the connector under the dash going to the clock spring, and measure the values of resistance between those two wires with each switch pressed one at a time, write the resistance values down, then re-engage the connector for normal operation.
To change the cruise speed using the existing provisions, you simply would present the resistance value across the two clock spring wires for speed increment (labeled 'Resume/Accel') and decrement (labeled 'Coast') - a momentary (pulse) for one increment of speed change (1 mph at a time decel, 2 mph at a time accel), or hold continuously for change at some rate change preset into the PCM.
I have made the measurement on my LH car, but it may not be the same as on the Sebring (though they likely are), so I won't bother publishing them here.
Here's an idea for a different project - maybe you will change your mind about your project and do this instead: Use the cruise control switches to trigger the transmission gear changes thru a custom electronic module that determines which cruise control switch was pressed, and, depending on which switch was pressed (Resume/Accel or Coast) send a pulse to the AutoStick gear incrememnt or decrement wire going to the TCM (or PCM depending on model year). This would allow changing gears as with AutoStick with your hands on the steering wheel. A switch on the dash could be used to set the function of the cruise control swithches to control the cruise control *or* to control the transmission gears. I wanted to do this to my non-AutoStick Concordes, but just haven't gotten around to it. Maybe you can do it as a project and sell me your resulting custom kit (at a significant discount for giving you all of this information). :)
Post back with any questions.
Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my address with the letter 'x')
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Bill Putney wrote:

Hi...
Respectfully wonder if this should have included a caution about the air bag system being part of the same wiring system?
Take care.
Ken
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Ken Weitzel wrote:

Hah! Good point Ken! The battery should be disconnected before going in there. However, there are so many failsafes, and with the ignition off, all power to anything related to the air bag is totally cut off. But you are correct - something could get inadvertently connected - not likely, but better to be safe.
Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my address with the letter 'x')
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Bill Putney wrote:

Umm - hey Brian - you still there?
Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my address with the letter 'x')
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I question the project, why bother? No insult intended, but there are several aftermarket cruise controls that either don't need a PCM interface, or are already designed for the interface [essentially a dealer item, but offerred in the market].
It seems to me that you are just re-inventing the wheel, per se.
Why not consider a push-button control for 4WD vehicles, mounted on the steering wheel, [for the elctronic systems, of course, not the manuals], that allows hands-on-the-wheel shifting into 4WD ranges? I may be wrong, but I've not seen a shifting system incorporated into the wheel, something much like the idea with the Autoshift.
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Yes, I am still around. Sorry for not responding earlier.
For some needed clarification, this system isn't for simply making an aftermarket cruise control system. What we are planning on doing is designing an aftermarket adaptive cruise control system, one that will automatically adjust your cruise speed depending on how close you are to the car in front of you. Essentially, it should allow for hands free cruising while in variable speed traffic.
Bill, I appreciate your reply. Thanks for the great input. While I haven't had a chance to look at this farther, I will certainly do that in the upcoming month or so. That other idea about the AutoShift does sound interesting as well; I'll discuss that with my group. Also thanks to you Ken for the heads up about the airbags. That would have been an unpleasant surprise.
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