How to Disable the Car from
Starting
You will need to know this for several test
Compression testing
Starting tests
Etc.
Older cars with external coil
• Disconnect battery power to the positive
coil terminal. This prevents the coil from
activating secondary ignition.
Older cars with external
coils pic
GM With External Coil
• Remove the wires to the Coil.
External Coils
• Some of the other cars just find the coil and
disconnect it.
Toyota
GM HEI
• On GM HEI disconnect the wire going into
the Cap
GM HEI
Conventional Distributor Cap
• On vehicles with a conventional distributor
cap, remove the coil lead from the top of the
distributor cap and ground it.
• Caution: Failure to properly ground the
wire may result in damage to the system.
EFI
• On some computer- controlled vehicles
equipped with fuel injection, hold the
throttle wide open while cranking the
engine. The fuel injection system
automatically disables itself because it
assumes that the engine is flooded. If engine
starts at first, shut it “off” and crank again,
keeping the throttle wide open. General
Motors cars do this.
EFI
• On a vehicle with throttle body injection
(TBI) or central fuel injection (CFI)
disconnect the fuel injector. This will
disable fuel flow.
EFI
• On newer cars you can disconnect the CKP
(Crank Shaft Position Sensor) that will
disable the fuel and ignition.
• Look up the location of the CKP in Alldata
or Mitchell.
EFI
• Remove the power to the fuel pump to
disable fuel flow on any vehicle with
electronic fuel injection (EFI)
• On some cars you will have to pull a fuse or
pull a relay to disconnect the power to the
fuel pump.
Inertia switch Fords
• This switch, is used on all vehicles with electric fuel pumps. This switch shuts
off the fuel pump in the event of an accident. The switch consists of a steel ball
held in place by a magnet. Upon sharp impact, the ball breaks loose from the
magnet, rolls up a conical ramp, and strikes a target plate that opens the switch
electrical contacts and shuts off the fuel pump. Once the switch is open, it must
be manually reset before starting the vehicle.
• Thanks to Alldata For Picture and text
Inertia switch
DTC’s
• NOTE: If any DTC’s are stored, clear and
ignore them.
• DTC - Diagnostic Trouble Codes - An
electronic signal stored in an automotive
computer, indicating the presence of a fault
detected by that computer.
The End