Printer Friendly Forum Posts - Engine crank with button

hi all,
i am putting in a button that will start a vehicle (simply crank the engine). The vehicle we are working on is an '02 Corvette.

what should be a fairly simple thing is driving me crazy because it is not working. What we want to happen is when the driver puts the key in, turns it to the RUN position, and then simply pushes the momentary push button that is installed. Since the actual key will be inserted and turned to RUN, EVERYTHING should be taken care of except the YELLOW starter wire.

We tested to see that the yellow starter wire IS getting 12 volts when the push button is pressed but the engine still does not crank. There is an alarm in the car but it is DISARMED so it should not be affecting anything.

And yet if you turn the key past run, the engine will crank right up. As far as i know, the turning of the key past run simply provides 12 volts to the yellow starter wire. so if the button is providing 12 volts to the yellow starter wire while the key is in the run position shouldn't the engine start?
HELP!
Thanks,
John

hello
i remember doing one of these cars a while ago and there was something tricky.

there is a yellow and black wire it can be used as a starter kill if the wire is cut it will not allow the car to start.
aslo test this wire., i believe it shows a ground signal when your cranking the car.

so what you would have to do its take that momentary switch and wire two relays

once side of switch ground.
other side of switch connect two wires
take one wire and connect it to relay 1

relay one setup
pin 85 wire from switch
pin 86 constant 12 volts
pin 87 constant 12 volts
pin 30 connect to starter wire.

relay two

pin 85 wire from switch
pin 86 constan 12 volts
pin 87 ground
pin 30 to yellow black wire.

this wire is located at the bcm.

try that

-------------
Jon
Installer/Help Technician
---coral springs florida---
mecp certification is not always needed. I have it and it has not helped me out at all. my experience out shines it.

If the key is turned all the way to the run position, then there shouldnt be any issue with any starter kill. The car see's the key and its resistor pellet and thinks everything is okay to start.

Since the key is in the run position, the ONLY wire i can think of that needs 12 volts is the yellow starter wire. that is the only thing that happens when you turn the key to the next step (starter position). subsequently, if the key is in run, you should be able to apply 12 volts to that yellow wire (from a relay controlled by a push button) and crank the car.

i tested the relay output and it does give the yellow starter wire 12 volts when the button is pushed - but then engine still doesnt crank. whats weird is you let off the button we installed, turn the key slightly to the right and it cranks.

whats different about these two scenarios?
John

Obviously something is being switched with the ignition switch that's not being taken care of with the push button..

Get a good schematic of the ignition switch circuit and see what it looks like.. where are you tapping the wires? right at the ignition switch, or are you running a wire to the starter solenoid?

Using a scan tool to monitor the computer systems might tell you something..

regards,

Jim

we are tapping the wires right at the ignition switch where the key goes in. with the button being pressed, we are simply emulating the key being turned one more notch to "crank". so instead of the key/cylinder giving the yellow wire 12 volts, we provide 12 volts to the yellow wire from a relay. its a very simple setup and it should work just fine. since the key is in, its not a VATS problem because it sees the resistor pellet and its not a starter kill issue because no alarm is armed.

If you sit there with the key in the RUN position and push the button supplying 12 volts to the yellow starter wire, it wont crank. Yet, when you release the button and turn the key one more notch, it cranks.

I'm confused why this simple thing wont work.

There is a couple of things that could be happening. First, there maybe a second starter wire, although GM doesn't tend to use this. The other, in the crank position an accessory or ing 2 wire may not have power which may disable a factory starter kill/antigrid or active a high power relay on the starter line ( or even the neutal safty switch.)

there is no second starter wire. the auto start alarm in the vehicle uses only one yellow wire (and it works).

and for your second idea, the key is never in the crank position when using the button. it is in the run position and we checked that all the accessory wires are getting the voltage they need, and they are.

still scratching our heads.....
John

I have a quick thing to try. Run a wire from the starter under the hood to the button in the vehicle and see if you can trip it right a t the starter. If you can than just disconeect that wire you quickly ran and properly run it to the starter and then your button is done. I ran into this problem on a toyota before and that was the only solution I could come up with and its still working fine.

I am not running any wire directly to the starter. That wire has some major current flowing in it and that is not the way to do this. There should be no reason that we basically cant emulate the car being auto started except the actual key is in, turned to RUN and you press a button to emulate turning the key once more to crank.

Its got to be something rather small because i have checked all the necessary wires and they all read as they should as far getting the 12 volts that they need etc. But why the auto starter can supply 12 volts to the yellow wire and start the car but the button cant is what doesnt make any sense.

Assuming that you've checked the yellow starter wire **AT** the starter.. right? Starter solenoid is getting 12v (using a test light) when you press the button?

Not sure what you mean by **AT** the starter - there is no reason i should have to go under the hood to do any of this. I am tapping into the wires where the key goes into the cylinder. If the car can auto start successfully (and it does) off those wires then I should be able to tap into the exact same set of wires and start the car with just a button. especially when the key is already in the RUN position.
John

You say there is an autostart in the car. Drop the unit, open it up and activate the starter relay with the key on. If it cranks, you can wire your push button to this (-ve). Dose the autostart have antigrind rely wired in? Try connecting at or down stream of the units tie in.

the starter relay inside the brain is connected to the cars yellow starter wire. so if we connect to it inside the brain or outside, then it should be the same thing. in other words, it should be the same thing if the alarm is giving the starter wire 12v or the button is giving it 12v.

the alarm does have an anti-grind feature and so does the car itself (GM put that feature in corvettes). We tied the button to the starter wire directly where it goes into the dash and out to the starter system so that none of the alarm business should affect it.

With the key in RUN, the ACC and other wires are receiving the voltage they need. The VATS is seeing the proper resistance from the key pellet and the clutch switch see's 12 volts when the clutch is pushed in.

What else needs to happen besides these few things?

calee4nyaboy wrote:

Not sure what you mean by **AT** the starter - there is no reason i should have to go under the hood to do any of this. I am tapping into the wires where the key goes into the cylinder. If the car can auto start successfully (and it does) off those wires then I should be able to tap into the exact same set of wires and start the car with just a button. especially when the key is already in the RUN position.
John

There is no reason why the pushbutton shouldn't work either.. but it doesn't. The key cranks the car.. the autostart cranks the car.. your pushbutton doesn't crank the car.. Sounds like a problem with the pushbutton circuit. So go back to the basics and check everything.. check for 12v up to the pushbutton. Check for 12v out of the pushbutton when the pushbutton is pressed. Check for 12v at the other end of the yellow wire, at the starter, when the pushbutton is pressed.

No, you shouldn't have to go under the hood.. but this should have been something simple. How much time have you spent on this that you could have spent doing something profitable?

I have checked ALL the wires including before and after the button. the button receives 12v and it gives 12v to the yellow starter wire when pressed (just like the auto-start does) In fact, I ran my own wire straight from the battery to the yellow starter wire (with the key turned to RUN, and it STILL didnt start)

This has got to be a matter of the car not seeing the VATS resistor pellet or the clutch is not pushed in for it to not start. WE HAVE CHECKED THESE TWO THINGS SO THEY ARE NOT AN ISSUE, this is just an example. Thats why i keep saying what other little things like this need to happen for it to start.

As far as time, I have all the time I need, it is not an issue what-so-ever...I just want it done right and working since it shouldnt be difficult.

John

calee4nyaboy wrote:

I have checked ALL the wires including before and after the button. the button receives 12v and it gives 12v to the yellow starter wire when pressed (just like the auto-start does) In fact, I ran my own wire straight from the battery to the yellow starter wire (with the key turned to RUN, and it STILL didnt start)

Have you determined exactly where that yellow starter wire goes to?

calee4nyaboy wrote:

This has got to be a matter of the car not seeing the VATS resistor pellet or the clutch is not pushed in for it to not start. WE HAVE CHECKED THESE TWO THINGS SO THEY ARE NOT AN ISSUE, this is just an example. Thats why i keep saying what other little things like this need to happen for it to start.

How have you determined that the clutch switch and VATS system are working properly?

calee4nyaboy wrote:

As far as time, I have all the time I need, it is not an issue what-so-ever...I just want it done right and working since it shouldnt be difficult.

John

'...since it shouldn't be difficult.'

Here's a hint.. that yellow wire doesn't go anywhere near the starter..

The yellow wire goes from the ignition switch (start position) to the instrument panel fuse block - fuse 14 (10a).

The 'center' of the starter circuit is the Theft Deterrent Relay.. looks like a standard four terminal relay. Using standard relay numbering, terminal 30 is connected to a 60 amp fuse in the fuse block (looks to be fuse 52) That fuse is connected to B+. Terminal 87 is connected to the starter solenoid. This covers the power side of the relay.

The coil side of the relay.. terminal 85 comes from the clutch pedal start switch.. the other side of the clutch pedal start switch is connected to our old friend yellow wire from the ignition switch (after it passes through fuse 14 and turns to the color purple). Terminal 86 comes out of the Theft Deterrent Relay and goes to the BCM. (Hey look... computer controlled starter!!)

Depressing the clutch sends power to the coil of the Theft Deterrent Relay.. the BCM gives the coil a ground path and throws the relay, which engages the starter.

Looks like probing the four wires on the Theft Deterrent Relay should tell you why the starter isn't starting.. might not tell you exactly why, but at least gives you a place to look.

NOTE - the terminal designators are for informational purposes only..

Again.. all this information would be on a decent schematic along with wire colors.. see if you can get one.

The reply that someone posted about the yellow/blk wire looks to be correct.. the yellow/black wire is the wire from the Theft Deterrent Relay to the BCM.

Jim

Jim,
AWESOME information. Thank you! The only wire that I have not looked at is terminal 86 of the theft deterrent relay that you mentioned comes from the BCM which energizes the relay during start.

I have tested both sides of the clutch wire (yellow and purple) and they are working as normal. also tested the vats and its working as normal. the button is working as normal giving 12v when pressed. with all the information we have in front of us, i still have to say i'm confused as to how the auto starter can start the car without having to go to the theft deterrent relay. i guess i've been scratching my head thinking "what is the auto-starter doing that i'm not doing??"

i figured turning the key to RUN will give all the wires coming out of the ignition harness the juice they need except the yellow starter. it will also allow the VATS to pass its resistance test. so, i gave 12 volts to the clutch and to the starter wire just to be sure both were covered but it still wont start.

Is there something off the top of your head that you can think of that an auto starter has to do that im not doing?

John

calee4nyaboy wrote:

Jim,
AWESOME information. Thank you! The only wire that I have not looked at is terminal 86 of the theft deterrent relay that you mentioned comes from the BCM which energizes the relay during start.

No no no... the wire that comes from the BCM to the theft deterrent relay is the GROUND path for the relay coil.. power for the coil comes from the clutch switch.

calee4nyaboy wrote:

I have tested both sides of the clutch wire (yellow and purple) and they are working as normal. also tested the vats and its working as normal. the button is working as normal giving 12v when pressed. with all the information we have in front of us, i still have to say i'm confused as to how the auto starter can start the car without having to go to the theft deterrent relay. i guess i've been scratching my head thinking "what is the auto-starter doing that i'm not doing??"

I don't know how you're testing the VATS system.. I'd be using a scan tool that interfaces with the vehicle computer.. what are you doing?

There are people here that are more knowledgeble than I about remote start systems; having said that I'd suspect that the auto start system has to tap into the circuit after the clutch switch unless someone's bypassed the clutch switch (specifically, there has to be a workaround for the auto start and the clutch switch). I'm wondering if the auto start wire connected to the yellow starter wire at the ignition switch is a sense line, not an output line.

calee4nyaboy wrote:

i figured turning the key to RUN will give all the wires coming out of the ignition harness the juice they need except the yellow starter. it will also allow the VATS to pass its resistance test. so, i gave 12 volts to the clutch and to the starter wire just to be sure both were covered but it still wont start.

Is there something off the top of your head that you can think of that an auto starter has to do that im not doing?

By probing the wires at the theft deterrent relay you should be able to determine where your problem lies.. we can eliminate the power side of the relay because the vehicle does start normally.. which leaves us with the coil side of the relay. Two wires.. one yellow and one yellow/black. Yellow should go hot when you press the starter button (with the clutch pressed). The yellow/black wire should be grounded.. I suspect this is where your problem lies; the BCM is not enabling starter.

I wasn't kidding when I said computer controlled starter..

What djfearny said in his post still holds true.. the yellow/black wire has to go to ground for the theft deterrent relay to allow the starter to operate.

regards,

Jim

Jim,
I knew what you meant about terminal 86 being a ground wire...my terminology might have thrown you. Since it takes a 12v connection AND a ground to energize a relay, I personally (in my own weird head) think about them as both being the wires that "energize" the relay...hope that makes sense.

Anyway, this problem was bugging me last night (to the point where i couldnt even sleep...lol) Basically, I thought of every wire that the auto-starter does and to make sure that it's been replicated when the button is pressed.

I know that the VATS system works properly because the car starts with the key and it starts correctly with the auto-starter (and its VATS by-pass relay)

Well, since the car acts just like the VATS is not working when the button is pressed, I started to think even though the key is in and turned to RUN maybe its not running through the VATS for some reason. You would think it would because the key is in and the resistor pellet would then be read. Then I thought maybe the VATS only engages DURING the crank position. If that is the case then it makes perfect sense why it wouldnt start. All i'd have to do is trip the VATs by-pass relay (that works when the car auto-starts) and it would then see the proper resistance. I think another thing the VATS does when its tripped, is that it has something to do with sending the ground wire to pin 86 of the theft deterrent relay.

I'll try this idea and let you know.
Thanks,
John

okay,
I have absolutely had it! I checked all the wires over and over again. Again, the auto-start works fine so here is a run down of how the alarm is wired and what it does and then in CAPS WHAT I'VE DONE TO EMULATE IT:

1) The auto-start alarm gives 12v to the ACC and to the 2 ignitions. PUTTING THE KEY IN TO THE RUN POSITION DOES THAT (ALSO TESTED WITH A METER TO VERIFY).

2) Then the alarm trips the VATS relay and dummy resistor so the car thinks the key is in. I TRIPPED THIS MANUALLY BY ENERGIZING THE RELAY SO I KNOW THE VATS COMPUTER IS SEEING THE RESISTANCE IT NEEDS TO SEE.

3) Lastly, the auto start's START wire gives the yellow clutch wire 12v so it thinks someone is pushing in the clutch. I HAVE ATTACHED 12V TO THIS WIRE STRAIGHT FROM THE BATTERY.

To emulate the auto-start, I did all of these steps but it still wont crank.

WHAT IN THE WORLD AM I MISSING HERE???

I am going to go looking for that YEL/BLK wire in the BCM that was previously mentioned.

What seems so odd is that I dont see anyway that the alarm is connected to the YEL/BLK or even controlls it somehow but it still auto-starts? Just seems weird that I would have to connect to that wire but it didn't?
John

WOOO HOOO!

When pushing in the clutch, hitting the button, and giving ground to the previously mentioned YEL/BLK wire in the BCM, THE CAR FREAKIN' STARTED!! I did not need to trip the VATS by-pass relay so it read the resistor from the key.

The smile on my face went from ear to ear. BIG TIME THANKS TO djfearny2 FOR MENTIONING THIS WIRE AND TO Mad Scientists for their input on this!

I still don't understand why the auto-start alarm can start the car without having to tie into this wire? It appears the YEL/BLK wire is tied to the theft deterrent relay so how is the alarm able to start the car?
John

calee4nyaboy wrote:

WOOO HOOO!

When pushing in the clutch, hitting the button, and giving ground to the previously mentioned YEL/BLK wire in the BCM, THE CAR FREAKIN' STARTED!! I did not need to trip the VATS by-pass relay so it read the resistor from the key.

The reason it cranked is because you grounded the yellow/black wire.. I don't know if it read the key or not, but by grounding the yellow/black wire you've bypassed the antitheft component of the vehicle security system. This means that you could probably start the car with a duplicate key that doesn't have a security pellet in it.

calee4nyaboy wrote:

The smile on my face went from ear to ear. BIG TIME THANKS TO djfearny2 FOR MENTIONING THIS WIRE AND TO Mad Scientists for their input on this!

I still don't understand why the auto-start alarm can start the car without having to tie into this wire? It appears the YEL/BLK wire is tied to the theft deterrent relay so how is the alarm able to start the car?
John

Evidently the auto-start is meeting all the requirements of the vehicle anti-theft system and thus, the car starts.

What exactly you are missing, I don't know... is how you've got it now ok, or do you still want to 'do it right'? If you can borrow a scan tool (this is what I use)

https://buy1.snapon.com/catalog/pro_det.asp?P65=&tool=diagnostics&item_ID=67130&group_ID=17428&store=snapon-store&dir=catalog

you can probably figure out why the anti-theft system doesn't like your pushbutton approach.

Jim

When I said I wanted to do it right, I merely meant with the button and a relay or two (since thats all it should take) What I did NOT wanna do is go through the hassle of going under the hood directly to the starter having to use big fat wires due to high amperage conditions etc etc.

I consider this "done right" and am very happy about it but if you consider the following I am still confused:

The alarm ties into the following wires in order to auto start the car:

ACC
IGNITION 1
IGNITION 2
STARTER (CLUTCH WIRE)
VATS

When using the push button:

With the key in the RUN position, I have tested that the ACC and IGNITION 1 & 2 receive 12v. The button gives 12 volts to the same clutch wire (also tested with volt meter) and the VATS was not necessary to alter because I found that it did in fact read the resistor pellet when the car successfully cranked with the button.

This is why it drove me crazy. There are very few wires, all easy to hook up and test and when I emulated them, it didnt work. And now i have to go to some tiny gauge wire that by-passes the starter kill? You can see why that doesnt make any sense...lol

Don't get me wrong, I'm really glad it works, but I dont like for it to just work, I like to understand (for my own knowledge and experience) what is going on and what the difference is etc. I still dont see where the difference is and how the alarm with its simple wiring can pull it off without needing that YEL/BLK wire. If I was the kinda guy that didnt care about all this stuff I would have just taken it to some shop and paid them to do it. I'm sure I'll do more stupid and useless things like this in the future and I was just hoping this experience would help me learn from it. As far as the scan tool, 7 grand is a bit much for me to spend.

: )

John

calee4nyaboy wrote:

When I said I wanted to do it right, I merely meant with the button and a relay or two (since thats all it should take) What I did NOT wanna do is go through the hassle of going under the hood directly to the starter having to use big fat wires due to high amperage conditions etc etc.

Simple would have been to take the pushbutton, one side wired to +12v, the other side to the purple wire off the theft deterrent relay.

Press button, engine cranks.

calee4nyaboy wrote:

I consider this "done right" and am very happy about it but if you consider the following I am still confused:

The alarm ties into the following wires in order to auto start the car:

ACC
IGNITION 1
IGNITION 2
STARTER (CLUTCH WIRE)
VATS

When using the push button:

With the key in the RUN position, I have tested that the ACC and IGNITION 1 & 2 receive 12v. The button gives 12 volts to the same clutch wire (also tested with volt meter) and the VATS was not necessary to alter because I found that it did in fact read the resistor pellet when the car successfully cranked with the button.

This is why it drove me crazy. There are very few wires, all easy to hook up and test and when I emulated them, it didnt work. And now i have to go to some tiny gauge wire that by-passes the starter kill? You can see why that doesnt make any sense...lol

Don't get me wrong, I'm really glad it works, but I dont like for it to just work, I like to understand (for my own knowledge and experience) what is going on and what the difference is etc. I still dont see where the difference is and how the alarm with its simple wiring can pull it off without needing that YEL/BLK wire. If I was the kinda guy that didnt care about all this stuff I would have just taken it to some shop and paid them to do it. I'm sure I'll do more stupid and useless things like this in the future and I was just hoping this experience would help me learn from it. As far as the scan tool, 7 grand is a bit much for me to spend.

: )

John

I think that if you probed the theft deterrent relay you'd find that the car didn't crank because the computer (BCM) didn't allow it. I don't know why, but I'd bet on either the factory anti-theft system or the anti-grind feature.

A good scan tool could probably tell you why the BCM locked out the starter.. (if that's the problem)..

How are you verifying the VATS system is working properly?.. You've mentioned a couple times that you knew it wasn't the problem, but how are you determining this?

How does the auto-start system interface with the VATS system?.. you mentioned that the auto start is wired to the VATS system.. how?

What make/model is the auto start?..

Regards,

Jim

Jim,
I totally agree with you that it has something to do with the theft deterrent system/relay. Probably because the VATS is not giving it the "OK". If this is the case, why the VATS is not giving the OK is what is troubling me.

The car is an '02 Corvette and the alarm is a Compustar 2WSS-AS. When using just the key to start the car, it starts fine because it read the resistor pellet. When using auto-start, it also works fine because I tied a VATS by-pass relay in with the alarm to read the proper resistance of the pellet (using a dummy resistor of the correct value). When using the button to start the car, the key is in the RUN position, the button is pressed (which gives the purple clutch wire 12v and the YEL/BLK wire at the BCM a ground via 2 separate relays) and the car starts. Because the VATS by-pass relay was NOT touched in anyway or energized when using the button, I figured the car read the resistor pellet...UNLESS giving the ground to the YEL/BLK wire by-passed the VATS system altogether making it not need to see any resistance what-so-ever.

But since I suspected that it might be the VATS giving me a problem (before I ever messed with the YEL/BLK wire) I tested the system as follows with still NO LUCK:

1) key in run position
2) press clutch in
3) energize VATS by-pass relay so I KNEW the car was seeing the resistance it wanted (I did this because I did not know if the car was reading the key or not in the RUN position) This step should have taken care of any theft deterrent issue like the YEL/BLK wire.
4) press button (giving violet clutch wire 12v)

If you think about it, this is EXACTLY what the auto start alarm does in order to start the car. The exact sequence of how my alarm starts the car is as follows:

1) it energizes the VATS by-pass relay
2) it gives 12v to ACC and both Ignitions
3) it gives the yellow clutch wire 12v
**car cranks**

It's such a simple procedure and I dont see the difference between the two?

John

Right off, the one difference I see is that for the auto-start and the key start, when you crank the engine the key is NOT in the 'run' position.. with your push button start it is.

Not saying this is the problem... to get a better idea I'd want to have a scanner hooked to the car's computer, but it's certainly one possibility.

Regards,

Jim

If it is working the way you want it, leave it. But I have installed a few remote starters, and have had this problem.. somewhat. When you start your car, you insert the key and go from off, on some to acc, then to gear shift unlock (on auto vehicles), then to on. When you go one step further, it goes onto the momentary *start* position. When the key is on the start position, the switch takes away power from all accessory lines. Now if you dont do this right, and you try to start with the accessory lines still powered, it may not let the car start. Ive seen that a few times. I then put relays in to cut accessory power when Starter wire is positive. That made the car start right up. But this was my bit of advice or something. LOL..