Bypassing CCM to Enable Starting
Heel & Toe
Joined: Mar 2005
Posts: 23
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From: N.Miami Beach Fl.
[QUOTE=rickso84;1571684925]Don't recognize the odd behavior but sounds like that relay switch line needs to be replaced back to what it was. What exactly was it that the locksmith changed?
Not exactly sure myself Rick. He showed me an approximate 9 " wire with a connector on each end, it was yellow, had to remove the bottom dash and said it connected from the ignition switch to ?????. said it was common that lead wire connection tends to separate after time and needs to be replaced. Didn't give me the old one. Everything started fine after he installed it so I trusted he knew what he was talking about. I'm not that techie about auto's but I did know the kill switch killed the engine when it wouldn't start because I was having the problem with the alarm system from the remote. I'm still not sure if the alarm system is working correctly as every so often it's not setting when I walk away from the car and have to walk back, listen for the doors to open and walk away again then it set's (horn toot's) Told the dealership about what happened and they didn't seem to feel there was any connection with the volt drain & vibrations or wrong with the security system. But Like I said it only started right after the engines kill switch shut the engine down.
Not exactly sure myself Rick. He showed me an approximate 9 " wire with a connector on each end, it was yellow, had to remove the bottom dash and said it connected from the ignition switch to ?????. said it was common that lead wire connection tends to separate after time and needs to be replaced. Didn't give me the old one. Everything started fine after he installed it so I trusted he knew what he was talking about. I'm not that techie about auto's but I did know the kill switch killed the engine when it wouldn't start because I was having the problem with the alarm system from the remote. I'm still not sure if the alarm system is working correctly as every so often it's not setting when I walk away from the car and have to walk back, listen for the doors to open and walk away again then it set's (horn toot's) Told the dealership about what happened and they didn't seem to feel there was any connection with the volt drain & vibrations or wrong with the security system. But Like I said it only started right after the engines kill switch shut the engine down.
Last edited by MyBaby; Oct 2, 2009 at 12:00 AM.
Advanced
Joined: May 2007
Posts: 82
Likes: 1
From: LA California
Second, assuming your circuit is the same as engle1147's @ http://forums.corvetteforum.com/c4-t...or-bypass.html , I'm not following you regarding the 5V regulator; can you provide a little more detail?
Finally, is it the case that the blue lead from the bypass connects to the CCM pin GD3 OR the ECM pin B/R6, since CCM pin GD3 completes a ground for the signal from the ECM.
.
Last edited by chevylu; Oct 2, 2009 at 06:12 PM.
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Instructor
Joined: Jun 2004
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From: Derry nh
I see the confusion on the pin numbers, but at this point not something I need to pursue.
As for the regulator, Radio SHack sells a 7805 5V regulator, a 3-pin large transistor-looking thing that takes in up to 18V and outputs a stable 5V (the other pin is ground of course). COnnected the 7805 input pin to switched battery and 5V output to the timer which causes the timer's output to swing from 0 to 4.3V, not 0 to 12V if it's powered right from the battery. I put a diode in the ground lead which raises the output from 4.3V to 5.0V, but it should work without the diode.
I would NOT connect the bypass signal directly to the CCM since that would be tying two output signals together which is bad. I put in a switch with the common pin going to the ECM, the normally-closed pin to the CCM (as it's connected normally), and the normally-open pin to the bypass circuit output. I want the CCM connected normally unless it refuses to start in which case I flip the switch, the CCM gets disconnected and the bypass signal gets connected. It's a momentary pushbutton switch so once car starts I release the button and the CCM's connected back normally.
As for the regulator, Radio SHack sells a 7805 5V regulator, a 3-pin large transistor-looking thing that takes in up to 18V and outputs a stable 5V (the other pin is ground of course). COnnected the 7805 input pin to switched battery and 5V output to the timer which causes the timer's output to swing from 0 to 4.3V, not 0 to 12V if it's powered right from the battery. I put a diode in the ground lead which raises the output from 4.3V to 5.0V, but it should work without the diode.
I would NOT connect the bypass signal directly to the CCM since that would be tying two output signals together which is bad. I put in a switch with the common pin going to the ECM, the normally-closed pin to the CCM (as it's connected normally), and the normally-open pin to the bypass circuit output. I want the CCM connected normally unless it refuses to start in which case I flip the switch, the CCM gets disconnected and the bypass signal gets connected. It's a momentary pushbutton switch so once car starts I release the button and the CCM's connected back normally.
Advanced
Joined: May 2007
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From: LA California
Thread Starter
Instructor
Joined: Jun 2004
Posts: 247
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From: Derry nh
Both circuits have some issues. The Zener circuit has C2 shown backward if it's an electrolytic as drawn. The curved side of the symbol goes to ground, not to 12V. As drawn, the cap would likely either explode or do something else bad.
In the regulator circuit, IC1 should be a 7805, not 7812. The 7812 will output 12V which is what we're trying to avoid. 7805 outputs 5V. Also I'd put a 0.1uF cap on pin 1 of IC1 to ground as shown in data sheet. The cap filters out noise from the input of the regulator.
With these corrections to the second circuit, it's the same circuit I built which works fine. Notice there aren't any values but I'm assuming you know what they are. The R3 trimmer is good to dial in the exact value your car is putting out. I've read that it should be 30Hz but mine was 32Hz to I trimmed the resistance for that frequency.
In the regulator circuit, IC1 should be a 7805, not 7812. The 7812 will output 12V which is what we're trying to avoid. 7805 outputs 5V. Also I'd put a 0.1uF cap on pin 1 of IC1 to ground as shown in data sheet. The cap filters out noise from the input of the regulator.
With these corrections to the second circuit, it's the same circuit I built which works fine. Notice there aren't any values but I'm assuming you know what they are. The R3 trimmer is good to dial in the exact value your car is putting out. I've read that it should be 30Hz but mine was 32Hz to I trimmed the resistance for that frequency.
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Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
http://www.thirdgen.org/vats_passkey_system
Put 12V to the solenoid terminal on the starter to confirm starter itself actually works 1st
Also need to jump the starter enable relay to confirm if a starter wiring problem or VATS problem
Check for 12V on starter curcuit at IGN switch when key in start position
Put 12V to the solenoid terminal on the starter to confirm starter itself actually works 1st
Also need to jump the starter enable relay to confirm if a starter wiring problem or VATS problem
Check for 12V on starter curcuit at IGN switch when key in start position
Last edited by rodj; Feb 6, 2011 at 09:40 PM.
Team Owner
Joined: Mar 2001
Posts: 54,124
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From: Cincinnati, Oh USA
Remove the kick panel above drivers feet and find the two wires from above the steering column that go to a 2 pin connector and unplug. Insert key in ign and measure the resistance across the two wires from above the strg clmn, you should measure the same as the ign key pellet. More than 4% error and VATS will not allow a crank or a start for 6 minutes. If you replace the ign lock, the new one has new contacts that connect to the pellet. You cannot connect a resistor the same value as the pellet across the 2 pin socket on later C4's like you can on early C4's but you need to disconnect the resistor and reinsert it on each crank attempt. Best to replace the ign lock and keep VATS which greatly prevents theft.
Pro
Joined: Jul 2001
Posts: 500
Likes: 5
From: Sterling VA
Great post. Unfortunately, I already know the starter is bad. If I place power to the solenoid it will click. However I am still not getting any signal to the starter when using they key. I suspect it's the VATS or a bad relay somewhere. Is there any indictor on the dashboard that will tell me if the VATS is active when I am attempting to start the car?
Le Mans Master
Joined: Aug 2000
Posts: 8,838
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From: Australia
