How to use the cruise control buttons for other purposes?

[stevenlee]

I would like to use the cruise control buttons on my '94 NSX for other purposes.

I am planning to use the cruise control main switch to activate 2 separate relays, 1 each for the 2 separate cruise control buttons only when the main switch is in the OFF position. In other words, turning ON the cruise control main switch would deactivate my after market switches. (I never use the cruise control on my small island, but don't want the after market switches to interfere with the cruise control if the cruise control is ever used.)

I'm looking for answers to these questions:
1. Does the on/off main cruise control switch control power (+) or negative (-) signal?
2. There are 2 wires to the main switch. Pin no. 5 and pin no. 15 on the main connector. The colors of the wires are light green and yellow. Which wire supplies the source and which wire sends the signal upon turning the switch to the ON position?
3. Do the 2 cruise control buttons control power or negative signals?
4. Are the signals coming from the cruise control buttons powerful enough to activate small relays? How many volts or is it straight to ground or some kind of specific resistance value?
5. If the cruise control main switch is in the OFF position, will the 2 cruise control buttons have any power or signal to activate small relays?
6. If I tap into the 2 cruise control switches to active small relays, will that interfere with anything else if the main cruise control switch OFF?

I know that these are technical questions but am hoping some of you electronic geniuses can help me to figure out the answers.

Much thanks!!!

 

[syndicate]

Assuming that the cruise main on/off switch is a +12v output and the accel/decel buttons provide enough current to drive relays (which I am sure they do):

Im doing this without looking at a relay, but this should work:

accel relay decel relay

_ <--- 87 (no connection) _ <--- 87 (no connection)

85 ---> l _ l <--- 86 (to ground) 85 --->l _ l <--- 86 (to ground)

l <--- 30 (to new function) l <---30 (to new function)

Connect the +12v output from the master on/off switch to BOTH 85s. This +12v should only be seen when you turn the master on.

You might have to add relays off of the 30 terminals if what you are using the accel/decel buttons for need more current. If this is the case, use the 30 output as the trigger on the new relays. Call me if you get totally lost, but email me first so I can allot time to talk to you.

Hope this helps,
Jay
919-539-2131

 

[syndicate]

damn it messed up the spacing on my drawing.....heres the drawing.

 

[stevenlee]

Syndicate, I'm not sure I understand your diagrams. If the Main Switch supplies power to the 2 relays only when turned on, would that mean that the cruise control functions are also turned on? I wouldn't want the accelerate and decelerate buttons to be active for both the cruise control and my after market relays at the same time.

I am thinking I would be using the 2 separate relays in the normally closed position to activate auxiliary functions from the accelerate and decelerate buttons only when the main switch is turned OFF. When the cruise control button is turned ON, the 2 relays would open and deactivate the contacts to my after market functions.

I'm not sure of the answers to the questions that I posted originally. Specifically, is the Main Switch sending Power or Ground? Also do the cruise control buttons get the power or ground directly from the Main Switch or from the cruise control module? Answers to these questions would help me to figure out if I can use the switches for other purposes and how to develop the circuits.

I have my dash and gauge cluster disassembled, and battery disconnected and wanted to complete the wiring before I put things back together. I have the service manual and the electrical diagram, but I don't understand the diagrams.

 

[syndicate]

So the way I have it wired in the schematic, when the relays see the 12v from the master cruise switch, they click. This means that 87 and 30 are now connected. Thats why you leave 87 open with no connection. When you turn the master switch back off, the relays fall into the rest position which connects 87a to 30.
Now like I said earlier, this allows the accel/decel buttons to work other things when the cruise is not in use, but you will still probably have to wire in 2 more relays (1 for each button) to operate whatever it is you want to operate. I am assuming this because I am not sure of the strength of the signal from the accel/decel buttons or their polarity for that matter. For example, if the accel button sends a ground signal when it is pushed and you need 12v to activate nitrous or something, you would have to hook up a relay to provide a 12v signal when it sees ground. I hope this clears up some of the confusion a bit.

You can easily test the wires coming out of the master switch to check for polarity. Use a digital multi-meter.

 

[stevenlee]

Syndicate, thanks for the added info.
I am planning on using separate relays for the 2 cruise control switches. I see that the wires coming from those switches go into a yellow SRS harness. My battery is disconnected and gauge cluster is removed. I am concerned that connecting the battery and testing for voltage/ground might accidentally activate the airbag if I make a mistake.
This is why I'm trying to find out how the OEM switches work.

I am wondering if the cruise control buttons use voltage (+) or negative (-) signals to activate the cruise control module functions.

According to the service manual, there is a light green/black and a light green/red wire coming from the decel and accel buttons going to the cruise control unit. I don't know if they get their signal from the cruise control master on/of switch. If they do, I would need to add a (+) or a (-) signal input into the switches that the switches would then give to the coils of their respective relays. This new signal would need to pass through the steering reel.

I'm wondering if I need to cut those 2 wires in the yellow SRS harness coming from those switches and wire up the relays in line to connect them when the master cruise control switch is ON. When the Master switch is OFF, the switches would disconnect the wires going to the cruise control unit and redirect them to the new relay coils.

I could connect the battery and start testing, but want to understand the electrical functions before I start cutting and testing wires to avoid an accidental deployment of the air bag.