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1993 STS Seville
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4 Posts
Discussion Starter #1
Bypassed the VATS on my 93 seville STS. Also done it on other passkey II vehicles. The normal bypass (signal gen with starter cutoff disabled) on all my other cars, the VATS box on pin A5 is for the security lamp that flashes when the VATS develops issues or fails. A6 is open on them. Now here is the issue. The VATS in the STS, has A6 used, in combination with A5, to start the text scroll on the dash stating 'security system problem, car may not restart' I am looking for the values, whether voltage, a signal, or if the A5 and A6 simply get grounded to each other etc, to stop the text scroll message. It's quite obvious since the entire VATS is removed from the vehicle that it will restart, lol! I just want the message on the instrument cluster stopped.
 

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2001 Seville STS, 1990 Seville (RIP), 1972 Sedan Deville
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26,323 Posts
:welcome: what do you mean by "the entire VATS system is removed"? I'm assuming you removed components as opposed to just installing a resistor? What VATS related codes are you getting?
 

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1997 Cadillac STS (BOSE w/AUX In, Massage Seats, URPAS, "Z")
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6,405 Posts
IN OBDII (‘96+) the IPC has a GND output on pin B10 connector C1. The GND returns to pin A10 on the C1 connector after is passed trough the resistor in the key. Meaning there are 2 wires running from the IPC to the ignition cylinder and when a key is inserted the circuit between B10 and A10 (i.e. the 2 wires going to the ignition cylinder) is closed trough the resistor in the key.
Installing a resistor (of appropriate value) between pin A10 and B10 will full the IPC. I am not sure how is a ’93 and why would be so much different, but then again '95 and older cars are so much different (in almost any aspect except the exterior body panels).
Sorry, can't be of more help.
 

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1993 STS Seville
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4 Posts
Discussion Starter #4
The resistor trick is only bypassing the key switch. it is not a permanent cure to future vats issues as it is only a partial bypass. The VATS system is completely removed, with an actual electronic bypass that generates the 30hz signal needed for the ecm to turn on the injector pulse. I don't do the resistor deal, it's useless to me as the passkeyII system will eventually fail and prevent the car from starting anyway... The 95 and older cars are not very different when it comes to the VATS, passkeyII except older passkeyII systems use a 30hz signal at 5VDC at 50% load and the newer uses a 50hz signal (same volts and load as the 30hz version) On my other GM cars, the security warning wire at a5, when disconnected for the full bypass, eliminates the security light flashing, period. the caddy though, with its text display, uses a slightly different passkeyII, since it has the extra wire at a6 on the PASSKEYII box.

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http://newrockies.com/the-problem-and-the-solution/ has more about the actual VATS bypass.
 

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'02 ETC ECS#533, '05 Escalade, '05 AWD Magnum, '74 455 OLDS
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1,948 Posts
I don't think you can get rid of the message. I installed at least 20 resistors without future issues. The only VATS problem I've ever seen in Cads is the tumbler switch.
 

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1997 Cadillac STS (BOSE w/AUX In, Massage Seats, URPAS, "Z")
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Actually are quite different, the validation of the key from IPC to PCM is actually data communication encrypted based on a password. There is a learning procedure for the password. Generally digital devices don't fail.
 

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1993 STS Seville
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4 Posts
Discussion Starter #7
Actually, VATS passkeyII are not different from year to year on many GM makes and models, you are probably thinking of the transponder equipped cars, that do need communication like that, in order to start and run. the vats, passkeyII the only communication is from the passkeyII box to the ecm, in way of a signal that is timed at 5 seconds, for the ecm to turn on the injectors. the chip in the key for those is a resistor that only completes a circuit that allows the passkeyII to actually function properly with the correct resistor, one of fifteen resistor values manufactured. To make getting the answer i am looking for easier, does anyone have wiring diagrams for the instrument cluster, the ecm and the bcm for the 93 sts Seville with the 4.6 v8?
 

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1997 Cadillac STS (BOSE w/AUX In, Massage Seats, URPAS, "Z")
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There are actually 20 VAT values and in the 96'+ PassKeyII cars the IPC is responsible from reading the resistor in the key and then sending the encrypted signal (data communication not just some 30khz signal), to the PCM. The PCM will then enable the injectors. The PassKeyIII is similar, the difference is the key has a proxy switch rather than a resistor and there is a exciter module around the ignition cylinder (basically a coil) that reads the code returned by the key chip and then send this value to the DIM (not IPC) after that the same encrypted message is communicated to the PCM.
I am telling you the cars are WAY different after '96, they may look the same but that's about it (even the body is different where you don't see like the entire floor).

Probably it doesn’t help you but this is the diagram of the '96+ PassKeyII. In your car just follow the ignition cylinder wires (the 2 thin ones) and see where is the other end. I would be somehow surprised if it turns out not to be the IPC. But then again in the older cars the chimes for example are handled by a separate module, so there are quite some differences.
 

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1993 STS Seville
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Discussion Starter #9
That doesnt help at all, since it is the schematics for the 96. Mine's a 93. As for 20 values for resistors.. only 15 for the passkeyII here in the states. As for the signal being magically encrypted, it's not. its a 30hz or a 50hz on 5vdc at a 50% load. Easy to make the full bypass in about 5 minutes when you have all the parts in hand. There MAY be a difference in USA verses other markets, yours for example in the way they did the resistors, passkey design, transponders etc. especially since we both have different info on the systems. Here is a list of the caddys, that use the passkeyII here, that uses the simple signal to enable the injectors. \
Cadillac
1986-1993 Allante
1982-1996 Fleetwood
1985-1996 Fleetwood Brougham
1988-1995 Seville
1992-1995 SLS/STS
1985-1995 Deville
1994-1995 Deville Concours
1988-1995 ElDorado
1994-1995 ElDorado Touring
1999-2007 Escalade
and they were still used up to 2011 in the Impala. The system I have is very common, easy to completely eliminate when it fails. The resistor is only a temporary fix for broken ignition pellet feed return wires as they are usually what breaks first since they are small, fragile and get moved around every time the key switch is turned. The electronics do fail, the lifespan of the VATS passkeyII box is between 7 to 10 years, longer if you are lucky. My current firebird, uses the passkeyII.. err used the passkeyII, lol, but had the key switch pellet feed bypassed with the resistor and eventually the passkeyII did fail. My alternatives were having the ecm flashed to eliminate the need for the signal to turn on the injectors, pay a lot more for a system that will fail again, pay for a signal generator that bypasses the system or simply have one made at work. I took the free route and had it made at work. The firebird was running again shortly after i got home :) and i dont have to worry with the VATS failing and leaving me stranded, ever. Same deal on the caddy, passkeyII failed, i eliminated it completely. Was even a smarty pants with it as i gutted the passkeyII box and put my bypass circuit board inside the passkeyII box. :) It started immediately and hasnt stopped yet, just want to get rid of the message on the dash about it, lol!
 

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1997 Cadillac STS (BOSE w/AUX In, Massage Seats, URPAS, "Z")
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Sorry my mistake, yes indeed there are just 15 VAT values:
1) .402 KOhm (.386KOhm-.438KOhm)
2) .523 KOhm (.502 KOhm -.564 KOhm)
3) .681 KOhm (.650 KOhm -.728 KOhm)
4) .887 KOhm (.850 KOhm -.942 KOhm)
5) 1.130 KOhm (1.085 KOhm -1.195 KOhm)
6) 1.470 KOhm (1.411 KOhm -1.549 KOhm)
7) 1.870 KOhm (1.795 KOhm -1.965 KOhm)
8) 2.370 KOhm (2.275 KOhm -2.485 KOhm)
9) 3.010 KOhm (2.890 KOhm -3.150 KOhm)
10) 3.740 Kohm (3.590 KOhm -3.910 KOhm)
11) 4.750 KOhm (4.560 KOhm -4.960 KOhm)
12) 6.040 KOhm (5.798 KOhm -6.302 KOhm)
13) 7.500 KOhm (7.200 KOhm -7.820 KOhm)
14) 9.530 KOhm (9.149 KOhm -9.931 KOhm)
15) 11.800 KOhm (11.320 KOhm -12.290 KOhm)

You are talking up to '95 cars, in your list I don't see the
'96-'97 Seville
'96-'99 Deville
'96-'02 Eldorado
All these cars were PassKeyII.
There is NO 30hz or a 50hz line between IPC and PCM, is all done on the data line, again I am talking '96 and up cars (and that is still PassKeyII). If you want I can post the full diagram of the IPC for you. There is no issue with the VAT circuits (part of the IPC) all failures to the system are basically broken contact in the ignition cylinder, you bypass the contacts with an appropriate size resistor and you are good to go. What you say may be a late ‘80’s early ‘90s issue (I understand from your posts is a different module, not part of the IPC).
First time when PassKeyIII was introduced in a Cadillac was in the '98 Seville and is basically the same system as PassKeyII except the key has a proxy switch and the reading of the key is done with an exciter coil, rather than some contact on the key pallet (also the IPC is not involved into this anymore). The PassKeyIII reads the chip (unique) code rather than a fixed value resistor as a result you can now distinguish between the keys (so it knows the driver).


Just checked my FSM for a 2000 Impala:
The Passlock theft deterrent system contains a Passlock sensor that is part of the ignition lock cylinder assembly. The body control module (BCM) provides voltage (B+) to the Passlock sensor through the Passlock sensor power circuit when the ignition switch is in the ACCESSORY, ON, or START position. The BCM also provides a 5-volt reference to the Passlock data circuit. The BCM provides ground to the Passlock sensor through the Passlock sensor ground circuit. The Passlock sensor interfaces with the BCM through the Passlock sensor data circuit.

When you turn the ignition switch to the START position with the proper key, the Passlock sensor applies a unique resistance value to the Passlock Data Circuit which pulls the 5-volt reference down to a unique voltage value, which is measured by the BCM. This analog voltage signal is unique and varies from vehicle to vehicle. When you attempt to start the engine, the BCM compares a previously stored (learned) voltage value with the circuit voltage value:

When the values match, the BCM sends a fuel enable password via the Class 2 serial data link to the powertrain control module (PCM). The PCM then enables the crank relay, and allows fuel delivery to the engine.
When the values do not match, the BCM sends a fuel disable password via the Class 2 serial data link to the powertrain control module (PCM). As a result, the PCM disables the crank relay, and does not allow fuel delivery to the engine.

There is no 30Hz signal to PCM either is all data line communication (way higher freq. and based on a communication protocol). I can see PWM signal on the 5V circuit read by the BCM, the BCM will then measure the average voltage. Once validated then is dataline communication to the PCM.
 

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Eddiests is there n e way I can get u to explain how to build something to bypass the system like u did. I have a 95 deville that I want to do the same to. N e help would be appreciated.
 

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1991 Cadillac Brougham D'Elegance 5.7 Litre, 1994 DeVille
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That doesnt help at all, since it is the schematics for the 96. Mine's a 93. As for 20 values for resistors.. only 15 for the passkeyII here in the states. As for the signal being magically encrypted, it's not. its a 30hz or a 50hz on 5vdc at a 50% load. Easy to make the full bypass in about 5 minutes when you have all the parts in hand. There MAY be a difference in USA verses other markets, yours for example in the way they did the resistors, passkey design, transponders etc. especially since we both have different info on the systems. Here is a list of the caddys, that use the passkeyII here, that uses the simple signal to enable the injectors. \
Cadillac
1986-1993 Allante
1982-1996 Fleetwood
1985-1996 Fleetwood Brougham
1988-1995 Seville
1992-1995 SLS/STS
1985-1995 Deville
1994-1995 Deville Concours
1988-1995 ElDorado
1994-1995 ElDorado Touring
1999-2007 Escalade
and they were still used up to 2011 in the Impala. The system I have is very common, easy to completely eliminate when it fails. The resistor is only a temporary fix for broken ignition pellet feed return wires as they are usually what breaks first since they are small, fragile and get moved around every time the key switch is turned. The electronics do fail, the lifespan of the VATS passkeyII box is between 7 to 10 years, longer if you are lucky. My current firebird, uses the passkeyII.. err used the passkeyII, lol, but had the key switch pellet feed bypassed with the resistor and eventually the passkeyII did fail. My alternatives were having the ecm flashed to eliminate the need for the signal to turn on the injectors, pay a lot more for a system that will fail again, pay for a signal generator that bypasses the system or simply have one made at work. I took the free route and had it made at work. The firebird was running again shortly after i got home :) and i dont have to worry with the VATS failing and leaving me stranded, ever. Same deal on the caddy, passkeyII failed, i eliminated it completely. Was even a smarty pants with it as i gutted the passkeyII box and put my bypass circuit board inside the passkeyII box. :) It started immediately and hasnt stopped yet, just want to get rid of the message on the dash about it, lol!
That list is wrong. Quite a few of those years don't use passkey at all, and several such as ~1990-1993 don't use passkeyII.
 

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07 STS-V 03 Allante
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Ok, I've tried the Newrockies VATS bypass and so far I cannot getting it working on my 93 Allante. The A3 is the cranking/fuel enable input between PCM and Passkey Decoder and A4 is the connection between Passkey Decoder and started enable relay. Seems that folks are talking about frequecy on A3.

Has anyone had any luck with these Newrockies VATS bypass?

Since I've tried to instal it I've made a mess of the PCM to Passkey decoder.
 
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