Eliminating the entire key assembly???

Karter2026

Well-Known Member
Good Evening,
After working on the Ariel Atoms wiring harness (still trying to get the engine portion ). What is the smallest battery one could use on the Goblin??? Been looking at the motorcycle batteries and even the riding lawn mower batteries (approx 400CA). My car is summer use only and the battery for an all season Cobalt said it needs 500CA. Anyone using something other then an OEM style battery???
THX,
Bruce
View attachment 10784
You can see where the Ariel Atoms battery was mounted (motorcycle I’m guessing) and that had a 2.0 supercharged Ecotec....
Here is what I found as a replacement battery for the Atom Odyssey Battery
 

BAR-AIR

Well-Known Member
There is no way that is the battery in the Ariel Atom 2. Maybe the newer ones take a look at the battery box pictured above. The Velcro strap is what holds the battery in place next to the two fuse blocks.
 

ctuinstra

Well-Known Member
Good Evening,
After working on the Ariel Atoms wiring harness (still trying to get the engine portion ). What is the smallest battery one could use on the Goblin??? Been looking at the motorcycle batteries and even the riding lawn mower batteries (approx 400CA). My car is summer use only and the battery for an all season Cobalt said it needs 500CA. Anyone using something other then an OEM style battery???
THX,
Bruce
Forget anything that has a CCA rating. Go with a LiPO battery look for the most mAh. They will be the only thing small enough yet powerful enough to crank the engine over. They work extremely well other than in freezing weather (CCA) which won't be an issue with this car anyways. EarthX has some great batteries. You just have to find something that will physically fit in there.

https://earthxbatteries.com/
 

DCMoney

Well-Known Member
I've been using ZZP's race battery, it's tiny compared to the stock battery. Not rated for cold weather, coldest ive had it out is 42 degrees. Used similar on motorcycles and they didn't want to start on extremely cold days..

I also used a spare battery I had out of my RZR a YTX12-BS, no issues with it.

https://zzperformance.com/products/race-battery

Drill and installed 1/4-20 nutserts to hold the battery holder in place.



 

bradr

Active Member
For readers who might not understand the wacky key switch inner workings, see the description below. In short, yes the key switch can be eliminated (ignoring issues related to PK3+). Here is how the system is designed to work in a stock Cobalt:

10886


The Body Control Module (BCM) outputs 12v and 5v to to the key switch. The key switch uses these two supply voltages and returns them the BCM in various combinations depending on key switch position. Here is what the BCM expects to see on the three input wires:
  • Connector 4 pin C8 - 12v in "Accessory and Run"
  • Connector 4 pin D3 - 12v in "Run and Start"
  • Connector 2 pin 56:
    • 12v in "OFF and Key Inserted"
    • 5v in "RUN"
    • 5v + resistor in "Start"
There are several ways to replicate this exact setup using switched and or relays. What I have found (only basic testing has been done) on my 2010 SS Turbo is that the BCM does not seem to care bout the multiplexed signal on connector 2 pin 56. It simply wants to see the ACC and IGN lines powered up with 12v, then it wants to see the ACC line drop out to initiate the start sequence (starter will engage). So, assuming that my simplistic testing is accurate and assuming this applies to more than just my year and trim level, you could use the following schematic as the most basic way to eliminate the stock key switch:
10887


Please note that the start switch is NORMALLY CLOSED. If using a push button, you may need to use a relay to invert the behavior as most of the fancy "Push To Start" buttons are normally open.

If someone has experience and knows of something that does not work properly when the multiplexed line is not used, let me know. There has to be something, I just have not run into it yet.
 

bradr

Active Member
I already read the thread you linked. The solution proposed there is theoretical and is designed to replicate the switch the "proper" way. I also believe the proposed schematic to be incorrect (based on the schematic, the start relay would need to be DPDT and wired to cut the accessory line when the start button is pressed to be 100% correct). My post provides an explanation of how the key system works, what the BCM is looking for, and my experience not seeming to need the theft resistor. Bruce was asking if the system could be simplified. It seems that it might be able to in some cars.

EDIT: It appears you can also start and run the vehicle using only the multiplexed circuit and not use the ACC or IGN inputs assuming you have bypassed PK3+ or have it wired up to get power before the start sequence. I also noticed, based on messaging from the BCM, it is clear that in either case where you are not properly emulating the key in full, there is some messaging missing because the BCM is not fully awake.

Although the engine starts and runs when only using some wiring, I cant say what else would not function properly as a result.
 
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ccannx

Well-Known Member
Not sure if I’m completely clear but it looks like power 12v can be applied to both acc and run/crank with a latching switch and then to start the car pressing or toggling a n/c momentary switch inline with acc will trigger the car to start ?

Assuming this probably only would work with VATS disabled
 
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