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What's the best way to connect to a CAN system


RalPh

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OK, so now I've got this '05 STS and I want to install the radar detector, laser jammer, (yea, I know..;) from my old car.

BUT, this thing is a networked system and a bit more complicated.

I have two thoughts,

1) if I used a relay (I used to pair a reed relay with a 30A "ice cubes" coil to make old cell phones blow the horn) and connect to a large accessory circuit (that wouldn't "notice" the draw) to supply power directly from the battery (now converted to "keyed" power)

2) something could be created, or purchased, that would sense 14V (engine running) to convert batt/keyed

I was disappointed to find the cigarette lighter had constant power in it :(

What are others doing for accessories?

TIA

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To answer your question, the best way to connect to a CAN bus is with a Microchip PIC microcontroller that supports a CAN bus interface. Whether that will work with the Class 2 serial data as used by Cadillac for the 1995 model year, or whether you can make anything of it, is another matter. Since the RFA and OnStar Class 2 interfaces can do things like unlock the doors, pop the trunk, honk the horn, and flash the headlights, the data is likely to be deliberately hard to deal with and I suspect that it will be pretty difficult to do much with the data even if you can read the bit streams. I don't see why you would want to do that anyway. The only time I ever ran up against that was last year when I wanted to figure out how to replace the analog phone with a digital phone. Unless you want to integrate the radar detector and/or laser jammer with the system, you shouldn't need to mess with the Class 2 network. In summary, I don't recommend it.

The cigarette lighter power cuts off after a period of time; I think it's something like 20 minutes. You can leave the radar detector on it all the time if you like, assuming that it doesn't draw more than a couple of Watts. If you need dimmed dash light power, it is available for the lights above the doors on both sides and in the rear view mirror, as well as under the dashboard. It may be available in the sun visors.

I suggest that you get a factory shop manual if you plan on modifying the electrical system. The schematics are distributed throughout them, particularly Volume II.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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I just got the Factory Service Manuals for my 1995 off of Ebay. I watched the auctions for a couple months, and just picked this one up for $16 plus $9 shipping. If you keep your eyes peeled you can find a deal on there. The covers had smudges on them from being in a garage, but the pages are clean and complete. I'm happy with mine.

WARNING: I'm a total car newbie, don't be surprised if I ask a stupid question! Just trying to learn.

Cheers!

5% discount code at RockAuto.com - click here for your discount!

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The cigarette lighter power cuts off after a period of time; I think it's something like 20 minutes. You can leave the radar detector on it all the time if you like, assuming that it doesn't draw more than a couple of Watts. If you need dimmed dash light power, it is available for the lights above the doors on both sides and in the rear view mirror, as well as under the dashboard. It may be available in the sun visors.

I suggest that you get a factory shop manual if you plan on modifying the electrical system. The schematics are distributed throughout them, particularly Volume II.

Jim,

You have probably already FORGOT more electronics than I will ever hope to know... but... ( I love reading your posts. I can understand them.)

I don't know about Ralph's 2005 STS, but my 2006 DTS DOES NOT shut off power to the cigarette lighter or the aux 12V plug... EVER.

I found out the hard way, after leaving it sitting in the garage for a week and a half, with the radar detector ON and cell phone charger plugged in. Dead battery.

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I don't know about Ralph's 2005 STS, but my 2006 DTS DOES NOT shut off power to the cigarette lighter or the aux 12V plug... EVER.

Check the fuse position for the lighter: it is common to have two possible fuse install positions, one being power direct from the battery and the other being power through the RAP system.

Physically it amounts to 3 slots for the two fuse blades.

Jim

Drive your car.

Use your cell phone.

CHOOSE ONE !

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To answer your question, the best way to connect to a CAN bus is with a Microchip PIC microcontroller that supports a CAN bus interface. Whether that will work with the Class 2 serial data as used by Cadillac for the 1995 model year, or whether you can make anything of it, is another matter. Since the RFA and OnStar Class 2 interfaces can do things like unlock the doors, pop the trunk, honk the horn, and flash the headlights, the data is likely to be deliberately hard to deal with and I suspect that it will be pretty difficult to do much with the data even if you can read the bit streams. I don't see why you would want to do that anyway. The only time I ever ran up against that was last year when I wanted to figure out how to replace the analog phone with a digital phone. Unless you want to integrate the radar detector and/or laser jammer with the system, you shouldn't need to mess with the Class 2 network. In summary, I don't recommend it.

The cigarette lighter power cuts off after a period of time; I think it's something like 20 minutes. You can leave the radar detector on it all the time if you like, assuming that it doesn't draw more than a couple of Watts. If you need dimmed dash light power, it is available for the lights above the doors on both sides and in the rear view mirror, as well as under the dashboard. It may be available in the sun visors.

I suggest that you get a factory shop manual if you plan on modifying the electrical system. The schematics are distributed throughout them, particularly Volume II.

I guess I have mis-stated what it is I want to do. I'm not actually trying to incorporate my accessories into the CAN system,,,, but merely power them :D

I thought, because all systems are monitored by the network, that I couldn't simply "tap-off" existing circuits to power accessories.

Where & How do I derive 12v (+) that comes on with the key (OK no key in my car, but you know what I mean) that won't interfere with the rest of the system?

OR, am I mistaken and I can do, what I've always done, and just probe-around for 12V with the car running, that's Not there when off?

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I would trace back the wire to the cigarette lighter and use that. Be sure and follow JimD's advice and make sure that the cigarette lighter power shuts off after a time. You can try it by just using the cigarette lighter outlet and leaving the radar detector where you can see an LED from outside the car. If it doesn't shut off after an hour, find the fuse and switch the position.

Note that if you use the fob or open a door, the cigarette lighter power comes back on. Be sure and don't touch the car while you're testing the power-off feature. It's there on my 1997 Eldorado, which shares most of the wiring diagram with the 1993-1997 Seville.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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I guess I have misstated what it is I want to do. I'm not actually trying to incorporate my accessories into the CAN system,,,, but merely power them :D

I thought, because all systems are monitored by the network, that I couldn't simply "tap-off" existing circuits to power accessories.

Where & How do I derive 12v (+) that comes on with the key (OK no key in my car, but you know what I mean) that won't interfere with the rest of the system?

OR, am I mistaken and I can do, what I've always done, and just probe-around for 12V with the car running, that's Not there when off?

call me old school, but why not run a wire, from off of the pos. batt. cable through the firewall ...

and the last time, that i did it, there was a nice rubber gasket that surrounded the steering column

shaft ... no drilling , just poke a hole through the rubber ...

then you have your power ... add an discrete on/off switch ... run it to your lighter ...whatever ...

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call me old school, but why not run a wire, from off of the pos. batt. cable through the firewall ...

and the last time, that i did it, there was a nice rubber gasket that surrounded the steering column

shaft ... no drilling , just poke a hole through the rubber ...

then you have your power ... add an discrete on/off switch ... run it to your lighter ...whatever ...

oops, my bad , you might want to add an inline fuse ...

the last time i did this, it was because of rad. cooling fans that were not operating

and i later found the bad relay that was causeing the problem but during the mean

while it was an easy fix ... if it looked like it was getting hot, i just hit a toggle switch and

the rad. fan ran as long as i wanted it too ...

Lane

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Toggle switch??? Dude, that's not old-school, that's Elementary School ;) (that's why, in my opening post, I talked about converting battery power to "keyed" power in 2 different ways)

So I open the hood and look in the fuse box and I see where the "outlet" (silly of me to keep calling them cigarette lighters now that nobody smokes anymore) fuses Do Have 2 positions to be plugged-in to. VERY interesting and clever of Cadillac to think of that!

Problem is,,, in it's original position it supplies constant (batt) power and in the other, No Power (acc/engine on or not) :(

Am I doing something wrong?

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^bump^

Some general info here:

http://www.aa1car.com/library/can_systems.htm

Not sure if it would interest you.

Regards,

Warren

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There is no means of avoiding the final collapse of a boom brought about by credit expansion. The alternative is only whether the crisis should come sooner as the result of a voluntary abandonment of further credit expansion, or later as a final and total catastrophe of the currency system involved. - Ludwig von Mises

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The best way to connect to a CAN system is with a STRING (I couldn't resist)

stringphone.jpg

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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