TransAmAbe

iTrader: (1)

OK, I've searched everywhere and need some help. I am trying to find a wiring diagram for the steering wheel stereo controls for my 2001 Trans Am with the Monsoon. The stereo stuff is all aftermarket and I want to use the controls for something completely different, such as wiring up a relay to turn on other lights/accessories, but I don't want to have to pull the steering wheel to find out which wires go to where on the switches. I have found wiring diagrams for the powertrain and the wiring/pinout guides for the stereo but nothing SPECIFIC to these switches.

Wiring coming out of the back of the steering wheel column under the dash is easy to get to, I just take off the two interior panels/covers under the steering wheel. I just figure pulling the steering wheel, especially with the airbag, is going to be a PITA. Anybody know which color wires to to where? And maybe, just maybe, where exactly they go before they go the ?one? wire that feeds into the Monsoon stereo harness?

Any help you guys can give me is greatly appreciated!

Abe

joshp14

iTrader: (5)

Here you go:

TransAmAbe

iTrader: (1)

3 minutes!!! Awesome!!!

Thanks Josh!

Abe

joshp14

iTrader: (5)

Np

WhiteBird00

iTrader: (4)

As you can see from the wiring diagram, there is only one input and one output wire for all the switches. The radio determines which switch is pressed by the amount of resistance introduced (each switch has a different resistor). You would have to build a logic circuit to use the switches for other accessories.

TransAmAbe

iTrader: (1)

Yeah, I'm not sure that it's going to work for what I was thinking of. Thanks for the help though. So as I understand it the radio had a logic circuit that interprets the resistance as a command and that's essentially what the PAC SWIX thing is as well? Correct me if I'm wrong, I'm trying to at least learn something if I can't go through with the idea I had.

Abe

WhiteBird00

iTrader: (4)

Yes, the radio (and the PAC adapter) has a logic circuit that works much like a binary bit field in a computer. The resistance values for each switch are set in such a way that no matter what combination of switches is pressed the total resistance will be a unique value that the logic circuit can break down to determine which switches are pressed. The individual resistance values are published in the service manual - you can see them in the circuit diagram posted earlier.

The switches have a power feed from the fuse panel and a single output wire that goes to the radio. The radio uses it's own power feed as a reference point and compares it to the return signal from the steering wheel to determine how much resistance has been introduced in the circuit by the switches. It then takes whatever action corresponds to the switches pressed.

TransAmAbe

iTrader: (1)

So how does one go about constructing a logic circuit? Is this the kind of thing that someone with a basic set of tools could wire up or am I getting into some serious solid state electronics that I need expensive tools to manufacture? I am not an electrical engineer, or an engineer of any sort for that matter, but I am not really scared of this kind of thing and would like to learn more.

Thanks for the info, I do feel like at least I learned one more thing about my car, if nothing else.

Abe

WhiteBird00

iTrader: (4)

Building a logic circuit doesn't require specialized tools (other than a good soldering iron) and the parts are readily available at electronic stores such as Radio Shack. The design of the circuit is the thing that would take some knowledge of electronics (voltage, logic gates, electronic relays, etc.). Basically, you would have to determine the voltage reduction caused by the resistance introduced by pressing switches and use that information to trigger relays that power individual accessory circuits.

FireSilverLullaby

iTrader: (5)

I was trying to think of a way to wire up an electric cutout to the volume switch. Is their any guides or good info about building logic curcuits.

TransAmAbe

iTrader: (1)

Well here's what I'm wondering. When you push the switch what's the voltage going to be at the blue wire that goes into the back of the radio? If I'm reading that diagram correctly, then the logic switch is integral to the head unit? I have an aftermarket head unit, so the dark blue wire that comes from the steering wheel controls just ends at the wiring harness for me. However, when I pushed the buttons on the steering wheel my test light didn't show any power at that dark blue wire. Is it going to read 12 volts at that wire? Maybe I'll get out there today with the multimeter instead of the test light. I like the e-cutout idea for the steering wheel controls.

Abe

FireSilverLullaby

iTrader: (5)

let me know what you find trans am. thanks

TransAmAbe

iTrader: (1)

OK, test with the multimeter showed something interesting: 12.4 volts at end of blue cable in stereo wiring harness when pressing button (any of the steering wheel control button), and car was off but key in on position. I can't figure out why the test light wouldn't light up but the multimeter shows voltage. I checked the test light, it's working fine. Regardless, it looks like that wire can be used to switch a single accessory, anything more than that would require a logic circuit.

I did find some definitions and in depth descriptions of logic gates/logic circuits online but no directions as to how to build one yet. I will keep you updated, or maybe someone else has a good resource.

Abe

TransAmAbe

iTrader: (1)

OK, so I got out there with my digital multi-meter, and the steering wheel controls put out 12 volts DC but no DC amperage. I switched through all the ranges on my meter and tried all the buttons but nothing. Tried both with car running and with engine off but key in run position. So what is up with that? I know enough about electricity to know that it should be at 12 volts or so (which it is) and that the amperage is going to depend on what the circuit is, but no amps at all? Isn't that wrong? Do I not know what the hell I'm talking about? Someone please enlighten me!

Abe

WhiteBird00

iTrader: (4)

Does your meter measure milliamps? For example, pressing the volume up button intorduces 1270 ohms resistance into the circuit. At 12 volts using Ohm's law (I = V / R) you would have only about 9.5 mA of current.

TransAmAbe

iTrader: (1)

WhiteBird, first of all thanks for all the help and information and for teaching me about this stuff.

My multimeter has three ranges:
2mA
20mA
200mA

Here's exactly what I got today. I have the multimeter red test lead hooked to the end of the dark blue wire for the steering wheel controls. I have the black test lead grounded to the frame of the car. This is killing me....

With key on, engine off, I get battery voltage no matter what switch I hit. So 12.25 volts on every single button. I also get zero amps on every single button. I tried to measure resistance but all I got was "OL" which I believe stands for "Over Limit" and/or "zero". I'm not sure if that is important or what. The ohm range goes from 200 to 2,000,000 and I tried all the ranges.

With key on, engine running, I get charging voltage with the same results. It was 14.4 volts or so no matter which steering wheel button I pressed, and it was wired up the same. I didn't change anything except for turning the engine on, and the amperages stayed at no reading all the way through as well. I have checked the fuse, the connections etc. and couldn't find anything out of place.

Does this make any sense at all? Thanks for all the help!

Abe

WhiteBird00

iTrader: (4)

You're connecting the leads to the disconnected dark blue wire? If the wire is still connected to the radio you won't get a current reading (just voltage). The meter has to be connected in series between the source and destination (ground) in order to read current flow.

I can't think of any other reason why you would have voltage but no current.

TransAmAbe

iTrader: (1)

No, the red lead on the multimeter is going to the dark blue wire where it ends at the radio. It is not hooked up to the radio as I have an aftermarket H/U and no PAC SWI-X adapter or anything. So the wire goes from the instrument panel fuse box to the steering wheel controls and then to the multimeter, which has the red lead connected to the end of the dark blue wire and the black multimeter lead goes to ground. To avoid confusion:

(Steering wheel)------dark blue wire------multimeter red lead-----(multimeter)------multimeter black lead------(grounded to chassis)

So when I push the button on the steering wheel, any button no matter which one, I get constant voltage but no current flow.

At this point I can't think of a reason either and I've about had it with this project and am going to move on to other things. However, I have at least learned more about the nature of electricity. Any other help would be appreciated but if you're stumped so am I and I'll get over it. Thanks!

Abe

irnbru83

you need to cut the dark blue wire and connect the multimeter leads to each end of the cut wire. Ammeters need to be connected in series, while voltmeters are connected in parallel. As stated before, it will be a tiny current. If you get a large current in this type of circuit, something is wrong and you need to kill the power before something dies.

Sorry for bumping an old thread, but i was looking for a wiring diagram and found this one and figured i'd reply.

Dave1970

iTrader: (2)

WhiteBird00,
Do you know of a write up to change the bulbs to LEDS? I found some write up on removing the switches and changing the bulbs. I'm confused on which way to place the LEDs to get the positive lead in the proper position. Thanks for you help.

Dave