punish_her

iTrader: (8)

I was thinking that as well but I started looking. They key switch is a continuity switch. The main fuses for the BCM are on the front side of that switch so when the circuit is closed the power is applied to the BCM. All the NATS is tied to the BCM. If you tied pins 1&2 together you will drain your battery since the front side is 12V constant.

I started working on a rough diagram of what Im talking about circuitry wise. I the ACC swap out during ignition is possibel and pretty easy.

The circuit would consit of:

sw1- Switch that controls 12V constant power to starting system
sw2- your push button ignition switch
SR1- Single pull double throw relay controling the ACC and IGN power
SR2- Single pull single throw system realy normaly open that when 12Vdc is to the ignition system it trips the Key switch circuit and holds the circuit as long as there is power.
SR3- Single pull single throw system relay normaly closed in unit inline with the start circuit after your push button switch, when 12Vdc passes through SR2 it opens the ACC ciruit. When start circuit looses power (after the vehicle starts) the switch returns to the normaly closed position restoring power to the ACC circuit.

It makes more sence on the paper in front of me.

EDIT: It looks like the Start, ACC, and IGN wires are comming from the same 12v source It may me possible to have a PDB drop the power to the 3 systems when SW1 is thrown. This would eliminate the need for SR1. I'll change this up real quick draw it up and get it on here.

punish_her

iTrader: (8)

Drew up the diagram and did a power diagram walk through. Since the 12V constant supplies the power to the entire IGN switch I went the power distribution block route oposed to the multi imput relay route (K.I.S.S.). It uses all 6 wires mentioned in the simplest design.

Here is what I got so far for the start sequence:

EVENT: SW-1 open
12Vdc supplied to the front side of SW-1

Current system state: IGN power off, ACC power off, ACC power off, BCM power off, Start switch unarmed

EVENT: SW-1 closed
12Vdc supplied to the front side of SW-1
SW-1 Closed: 12Vdc supplied to power distribution block (PDB)
12Vdc at PDB
12Vdc Supplied to IGN circuit
SR-2 (N.O. 40amp 12v) closes completing key switch circuit.
BCM recieves power from source
12Vdc Supplied to ACC circuit through SR-1 (N.C. 40amp 12v relay)
12Vdc Supplied to front side of SW-2 (Push button start/stop switch)
SW-2 start armed

Current system state: IGN power on, ACC power on, BCM power on, Start switch armed

EVENT: SW-2 momentary closed
12Vdc Supplied to front side of SW-2
SW-2 Closed: 12Vdc supplied to power SR-1
ACC circuit opens by SR-1
Vehicle starts
IGN has 12Vdc

Current system state: IGN power on, ACC power off, BCM power on, Start switch active, engine starts

EVENT: SW-2 Open
12Vdc Supplied to front side of SW-2
SW-2 open: 12Vdc removed from SR-1
ACC circuit closes by SR-1
Vehicle is running
IGN has 12Vdc

Current system state: IGN power on, ACC power on, BCM power on, Start switch armed, engine running



KP can you please let me know if you see any flaws in this logic diagram or walk through.

EDIT: After getting an outside look at this it seems possible to wire this up into one of those radioshack black boxes. The leads comming either be made so you can solder or end in an terminal so you would just strip, poke, and secure. I prefer solder and heat shrink my self. It would just look like a black box with labled wires comming out of it. All the relays and PDB will be in the sealed box. I did a crude paint diagram.

KPierson

iTrader: (1)

Once you start calculating power draws for each circuit you will find that your layout most likely won't work, due to current limitations. You would need at least a 40A toggle switch to prevent the switch from getting hot and catching on fire. You will most likely struggle to find a switch with a high current rating that will look nice enough to install in a Z. The place that I get a lot of switches/wire from only has toggle switches rated to 21A. Whatever route you go make sure that all the wiring is sized appropriately to handle the max loads of the circuit.

You're best bet would be to use a low current switch to switch on two 30A relays (60A total capacity) to power all the circuits. (At this point, you could even isolate the ACC from the IGN and use two seperate switches)

punish_her

iTrader: (8)

How does the ignition switch keep the current drop down then? The ignition switch has the 12Vconstant incomming and the 3 outgoing for power. That should have the same power drop as this set up. The ignition switch is the same as the PDB. According to the the wiring diagram, when the switch is in the IGN pos, the ING and ACC have power on. Looks like the reason that ACC looses power is to mainly keep the instintanious current drop from the starter from over loading the system.


Yeah that would be easier if there isnt a decent enough switch arround at the right amprage. I realy wasnt invisioning one of those frankenstien big brass switches on the dash. That would suck alittle bit.

The 2 switch route I thought about but trying to limit the number of switches. Not realy a fan boy of the prostock dirt track multiple rocker switch look.

If the ACC and IGN are isolated from each other, where would you get the 12V constant from to power each circuit from. The way the system is currently set up the 40A fuse on the 12V constant and is intended for all threes lines, but 2 at any give time. These 3 lines only control relays that provide the actual power and a few direct powers for each which go through seperat fuses for each sub circuit. Depending on the relays the milliamps may not make a significant drop on that system. I gotta see what the actual drops are for all the circuit first. The main wiring diagrams are in the Power ground section on PG-4 and PG-26.

KPierson

iTrader: (1)

I would guess that the OEM switch is rated at at least 40A. They wouldn't put a 40A fuse on a switch that was rated less then that. You also have to remember that the OEM switch is at least a 4PST switch, so it has several different sets of contacts for the current to travel through (depending on key position). I would venture to guess, with the size of the wire ran to the key switch, that all contacts and all wires are good for the entire 40A load. All the ignition wires are heavy guage.

Using two relays in parallel would increase the current capacity to handle the maximum load the fuse will allow. You wouldn't really be isolating the voltages, as all voltages in the car, no matter where they come from, originate from the battery and are all the same voltage. The only reason for the 2nd relay is because most standard automotive relays are rated at 30A. You may be able to find a 40A relay, but I wouldn't run a relay at its full potential on a critical circuit when there are alternatives readily available (2 30A relays would give you a 50% cushion on a 40A load).

If you put a 40A fuse on a 35A switch then the switch becomes a fire hazard at any load above 35A. Now, they don't typically load the line close to 100% (they shouldn't go past 75%, but its hard telling how they did it without actually logging the current during every different possible battery situation. It is never good practice to put something (switches, wires, etc) in an existing circuit that has a current capacity less then the fuses on the line (this is one way aftermarket wiring electrical fires start).

You could easily set up a circuit using a couple relays and a push button that would allow to only turn the ACC on or the ACC and IGN on depending on different conditions. A push button may look a bit better to, but thats opinion.

KPierson

iTrader: (1)

Current drop isn't the issue nor is it even a factor. I think you are thinking of voltage drop, a common issue with car audio.

I hit on it in my last post, but i want to make sure I got my point across. If you run more current through a device then it is rated for it will heat up, possibly to the point of catching on fire. Because fire is a real issue here, you want to err on the side of safety and make sure you have components that can dissipate the current.

DeusExMaxima

iTrader: (1)

Anyone know anything about the Keyless Go system in the Mercedes? The reason I ask is that this start button is located on top of the shift ****:
http://www.performanceproducts4benz....&vehicle=32090

punish_her

iTrader: (8)

I guess I miss read, or cant picture exactly what you were say. Yes I know that using an under rated part will cause it to heat, using an over rated part turns the wiring into a potential hazard. But a current draw is dependant on the item thats in that circuit. The same reason why a 10 and 15 amp fuse in a ciruit, having the same power supply; when the 15amp fues blows the 10 doesnt go. The item behind the 15amp fuse exceded the rating.

Current load is dependant on the items that ar drawing the power. Look at the diagram on PG-4. Before each item that draws power there is a fuse inline for more than the rated power of the circuit to follow. Yes I know wire choices, motors, etc all play into that decision. But if you look there isnt a fuse on the front side of the ignition relay or Acc relay. So they dont expect a signifigant current load with the inductance in the relay. Would you realy expect that relay operation to excede 15amp when the are similar ralays unfused on the same circuit.

Infact the first fuse going towards pos. in that circuit that would effect either forementioned ralays is "M" a 40A fuse then the 100A followed by the 120A. For safety a 15 amp fuse can be placed in line after the relay on the back side, so when the circuit is opened or closed if the fuse rating is exceded the fuse blows preventing the wire and relay from becoming a lighter. Its hard to tell exactly what the current load of 2 smaller relays in parallel or one big relay. I really dont think that a relay will have more of a current drawn than say a the exact same IGN relay or ACC relay.

Im gonna check out some of my electronics wiring books to see what they say about it.

punish_her

iTrader: (8)

No clue, Im guessing multiple reciever antenna's that have a 12v constant instead of a switch triggered one like the NATS Antena. No clue, its realy hard to tell. Hell we have teh manual for OUR own car and its a pain in interprating it.

punish_her

iTrader: (8)

Found a current calculator that may clear up some of the current questions.

KP you may recognize the site: http://www.the12volt.com/ohm/page2.asp#current

Been a member since April 2005 huh? I was looking arround there for info on relays and was like WTF!!!

So yeah what would be considered a nominal amperage load that would be dangerous? I've been finding DPST, DPSD, and SPST relays arround 90ohms which looks like it drops 133 mA @ 12Vdc. Would this work out...http://www.the12volt.com/installbay/...TID~96494~PN~2. You even posted in there too. With there being one relay that has an effected current load, couldnt the capacitor and resistor in series work for keeping the current down on the relay?

Looks like a DPST switch can throw a SPST relay that applies power to the circuit and can handle the 40 amps as well as the Key Switch. This only leaves 1 SPST N.C. relay in that circuit thats only is only activated in the start sequence. That reudces the unecessary load on the system to 133mA if the restance of the relay is 90ohms.

Just currious since your module has alot of circuitry, what current does it drop?

KPierson

iTrader: (1)

The diagram I'm looking at shows that there are 5 fuses that are hot in the on and start position with a total capacity of 55A in addition to the relays you are talking about.

Using relays will add roughly 200mA load for each relay. However, you have to remember that you will still need current capacity to feed through the contacts of the relay, so you will still need something that has a high current capacity (ie 30amp Bosch relays).

The advantage to a relay is you can use a low current switch to turn the coil on (200mA). The contacts of the relay are then capable of delivering up to 30A of current per relay. When using the relay though, you will still be sourcing all your current from the same 40A fused wire under the dash (unless you run a power wire directly to the battery).

I haven't actually tested the current draw of our module, but I would expect it to be under 10mA at idle. During cranking it will be a little more then 200mA (starter relay).

punish_her

iTrader: (8)

Let me see if my logical reasoning is correct... If the relay is rated at 90ohms at 12 Vdc it will have a current draw of 133mA. If the realy were say 120ohms, that would place the current drop at 100mA. Reducing the current drop as shown in the above diagram would be helpful in bringing down the draw.

So with one relay in serise with your switch on start up would draw an extra 400mA. Now there is a possibility of running a dedicated line from a main power source close to the 160 amp fuse where the 200mA drop wont effect the system much, through a terminal block fused with a 40A fuse (just to be safe). Use that for the starter relay.

If that terminal wire was the case running a DPST relay powered with through a switch powering the IGN ACC on one lead and START on the other would work. The start current and the relay current will be far less of an impact, No?

There are definately MANY possibilities out there, its just finding the simplest method to effectively make it work. The main facts are: to make it work there definately needs to be a SPST NC realy controled by the start to switch open the the ACC circuit when the start is activated; power needs to be controlled into the system by a relay; the Key switch need to be on when the car is on, current needs to be kept to a minimum with in the circuit.

punish_her

iTrader: (8)

What are you using to refrence your wiring, just curious because on PG-12connector E119 for the ignition switch is shown and has only 5 pins. Just wondering if you have a newer modle service manual or other after market wiring manual for the Z. Just making sure we are looking at the same info here.

KPierson

iTrader: (1)

I was looking at the pg.pdf file for the '03 350Z. If you scroll down to the layouts it gives wire colors with pin references. There is no reference to pin no. 4 which may mean it is blank, or that it doesn't even exist. I would guess that it was blank, because typically they don't number non existant pins in harnesses.

KPierson

iTrader: (1)

I think you've gone astray here.

The current of the relays isn't a big deal at all, as long as the current is below what the switch is rated.

With the switches off, the relays won't draw any current at all (when the car is at rest). When you are in the car and flip the switch to start energizing relays, as long as you don't let the car sit in that position for 3-4 days the current draw won't matter. An extra 2-500mA load on the battery during cranking is nothing when considering the starter is pulling anywhere to 100+ amps on its own.

The only reason I brought up the relays, again, was so you could replace a high current switch with a low current switch to safely and reliably turn the igniton on and off. Again, when switching the ignition on and off through a relay you can basically use any switch you can find because current isn't an issue. If you don't use relays to switch the ignition you will need a switch rated at at least 40A in order for it not to be a fire hazard.

punish_her

iTrader: (8)

Hmmm... Yeah I notice the PG.PDF is a little scant on some things but if you look in the SC.pdf, SC-12 shows pin 4 of E119 (5 pin connector) being white/red and for the starter circuit. Pin 5 is fo the DTRL system that most dont have so its typicaly blank. Thats one of my biggest gripes about the service manual. you have to find multipe refrences because it may not cover something 100%. Good example the ignition switch setup. Its scattered through 2 or 3 sections over several pages. Unlike a haynes manual where its all right there. You have to dig more for info.


Thats what I was thinking too but you seemed adamant about the current draw being too mouch with the relays and I guesse it through me off. It doesnt help that Im looking at this stuff all the time and second guessing it. I started worrying more about reducing the instantanious current drop than any thing else. OOPS Over thinking it I guess.

Its all good though becasue it got my mind thinking in diffrent directions and rembering all te DC theory and what not I've had but not used in forever.

KPierson

iTrader: (1)

The 2nd starter wire is in my car - I have it hooked up to my push button start. Like I said before, if you live in a climate where it may get cold I would hook it up just to be safe. I have read several threads where people couldn't get the car to start in cold weather without the 2nd starter wire hooked up. DEI recomends hooking it up during remote start applications. The service manaul doesn't show where it goes (besides the DTRL) but it is still in my car, even though I don't have DTRL.

punish_her

iTrader: (8)

OK I know why they do that. It makes sence to me know, when you said cold weather. Its making sure the juice is getting to the starter. The starter can handle both no problem, but in a cold situation where the starter is more resistant to movement (situation that would draw more current) it just provides that extra pathway to ensure the car will start. Since the volatge and current are the same its just like doubling the thickness of the wire. Thats about it.

So you have E119 pin 5 hooked up to the starter relay at pin 11 in the the IPDM E/R Looking at the diagram?

I just saw some thing that made me go Hmmmmm. The clutch interlock is the signal that closes the relay to start. I knew it had some thing to do with it but but directly driving the coil for the start relay, that I didnt know.

KPierson

iTrader: (1)

I hooked them up directly at the keyswitch under the dash - a white/green wire and a white/red wire. Like I said, I am honestly unsure where the 2nd starter wire goes and not 100% sure it needs hooked up, but everyone says to hook it up so I did.

I just did a current draw of the KPtechnologies push button start system - at idle it pulls 1.6mA. With the 'LOCK' LED illuminated its 11mA.

punish_her

iTrader: (8)

Nice. Thats next to nothing.

What are the additional safety features of your switch? I know the RPM cut out thing, any more?