Will using a vats bypass module cause battery drain???
Thread Starter
Le Mans Master
Joined: Aug 2007
Posts: 8,735
Likes: 412
From: WV
Will using a vats bypass module cause battery drain???
I've always heard that leaving your key in the ignition will cause drain on the battery because your completeing the vats circuit. If you pull the key you break the circuit stopping any drain from taking place.... If you install a vats bypass module, wouldn't you be doing the same thing as leaving the key in the ignition all the time, because your completeing the circuit with the vats module and never breaking the connection..Could this kill a battery in short order or is it a very low draw?..I know WVZR-1 has the answer to this one...
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Last edited by WW7; Apr 2, 2014 at 06:59 PM.
Safety Car
Joined: Apr 2011
Posts: 3,660
Likes: 22
First of all, a RESISTOR in the ignition key VATS cable is not a VATS BYPASS. That's a KEY bypass...BIG difference.
That is simply "jumping" the sensor circuit like any other jumper wire except this circuit has a precise value in resistance.
A "BYPASS" module is a solid state module that transmits the 50hz signal without the key as part of the circuit, to the ECM that then allows starter and injector enable. The ECM looks for that 50hz 'code' before it allows things to operate. A module bypass unit has no need for the key in any way.
The REAL VATS needs assurance that the correct key was in-place and not a screw driver or hot-wire, so the pellet is step one in the VATS sequence. Once that step has been completed and the VATS module reads the key, gives its ok and moves thru the rest of the permission process. Its 50hz signal MUST have that key resistance as permission or it locks everything out for a few minutes. The bypass module simply sends that permission without needing the keys resistance value to be met.
I would not think that completing the key circuit would cause battery drain. VATS is not a voltage actuator, its just a reference signal that's low/no voltage. Yes, its 12v as are all things in the C4 system, but it has no servo or actuator to use voltage.
The module bypass only transmits during the starter operation as the circuit was designed. Once the key is released from start to run, the module goes dark again.
That is simply "jumping" the sensor circuit like any other jumper wire except this circuit has a precise value in resistance.
A "BYPASS" module is a solid state module that transmits the 50hz signal without the key as part of the circuit, to the ECM that then allows starter and injector enable. The ECM looks for that 50hz 'code' before it allows things to operate. A module bypass unit has no need for the key in any way.
The REAL VATS needs assurance that the correct key was in-place and not a screw driver or hot-wire, so the pellet is step one in the VATS sequence. Once that step has been completed and the VATS module reads the key, gives its ok and moves thru the rest of the permission process. Its 50hz signal MUST have that key resistance as permission or it locks everything out for a few minutes. The bypass module simply sends that permission without needing the keys resistance value to be met.
I would not think that completing the key circuit would cause battery drain. VATS is not a voltage actuator, its just a reference signal that's low/no voltage. Yes, its 12v as are all things in the C4 system, but it has no servo or actuator to use voltage.
The module bypass only transmits during the starter operation as the circuit was designed. Once the key is released from start to run, the module goes dark again.
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
The VATS module does not get power until you turn on the ignition, so you can't drain the battery by leaving the key in the cylinder.
I do pull my key out a small amount so the stupid key warning chime won't make that obnoxious noise, though...
I do pull my key out a small amount so the stupid key warning chime won't make that obnoxious noise, though...
