My concern is that when I change to the new engine/ECU combination
that the resistor key will no longer work due to a difference in
resistance in the circuit. Also, I don't know if all L98/LT1/LS1
engine/ECU's use VATS. If not then I will be okay, but if they do, I
understand that the resistance value can be different and therefore
not work with the current key/ingition switch.
I guess the most simple solution would be to know how to bypass or
'trick' the system into thinking the correct resistance is always
present. I am planning to implement an alternatve system that will
protect the car from theft.
Your car should have a VATS module under the dash somewhere, which is
designed to work with the particular key you have, and the computer type
you have. A computer for a different engine that uses the same VATS
scheme should work fine with your VATS module....I'm guessing.
Folks who make harnesses for engine swaps usually have a way to bypas
VATS, I think the most common method is to reprogram the PROM so that
VATS is turned off. A lot of these engine swaps are done on old cars
and the owner doesn't want the anti-theft system.
I swapped a TPI engine into an early Vette using the 90-92 Camaro type
computer/harness and the stock PROM, and fooled the comptuer into
thinking it had a working VATS module by feeding a 30 Hz square wave
signal into the appropriate pin of the comptuter (using a homebrew
circuit with a 555 timer chip). All that the VATS module does on these
systems is to use the resistor in the key as an element in an oscilator,
if it's the right resistance than the signal is the right frequency, and
the comptuter turns on the fuel; if the signal is missing or it's the
wrong frequency, the computer turns the fuel injectors off.
Uh......maybe it's not the VATS, but the ignition switch itself, or the
lock or rack/pinion? The ignition switch is mounted on the column,
behind the dash, and actuated with a rod. The lock itself turns a
pinion gear which moves the gear rack at the top of the rod. WHen this
stuff gets worn, sometimes it does not pull the rod all the way, and the
starter won't engage. But without performing a "laying on of hands",
it's pretty hard to diagnose it accurately.
Also, if it's a tilt column, and the column is loose between the upper
part and the lower part (you can wiggle the steering wheel back and
forth sideways), it could just need the column internal screws
tightened...which is a job for someone who knows what they're doing.
Or it could be that the 89 system is different from the 90-92 system
that I described?
Could be. I had two ign keys become intermittent, then totally fail.
Turning the key would turn on all the electrics, but the VATS module
wouldn't recognize the circuit resistance, so it set a vats code in the
ECM and disabled the starter relay circuit. It requires 5 min of ign
off to cancel the code for a re-try. I simply went to the dealer and
got a replacement key each time. Been fine since.
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