3 Wire Positive Pulse Systems
This doorlock system is similar to the 3 wire negative pulse system except the
doorlock switches send +12 Volt pulses to operate the doorlock relays/control unit.
Examine the wires on the back of the doorlock switch:
1) One wire will show +12 Volts, regardless of the switch's position.
2) One wire will show +12 Volts only when the switch is pushed to "lock".
3) One wire will show +12 Volts only when the switch is pushed to "unlock".
Warning: The Positive pulse system can be confused with the 5-wire Reversing
Polarity system. This is because both systems show +12 Volt pulses on the “Lock”
and “Unlock” wires when the vehicle’s switch is pressed respectively. It is critical
to identify which system is present, since if +12 Volts is pulsed into a Reversing
Polarity system, which rests at ground, a direct short circuit will occur.
3 main differences between a Positive pulse and a Reversing Polarity system:
1) In a Reversing system the Lock/Unlock wires
rest at ground, while in a Posi-
tive system the wires
show partial ground through the relay’s coils.
2) The doorlock switch in a Reversing system will have 5 wires, while a Positive
pulse system the switch will have 3 wires.
3) A
Positive pulse system uses factory relays or a control unit, a Reversing
system
does not.
29
12
12-Gauge
Green Wire:
Starter Output
Connection Required
.
Connect the Green wire to the vehicle's Starter
wire. This wire will show +12 Volts only when the ignition key is in the "Start"
position. This wire is also found in the ignition switch wiring harness (see diagram
on previous page). Some vehicles have a second Starter wire known as a "Cold
Start" wire. When this is encountered, an optional relay may be needed, config-
ured to the 3-pin Red port, to energize the second Starter wire (see pages 33-
34).
Note: If a security system is present which utilizes a starter interrupt circuit, the
Green wire must be connected to the Starter Motor side of the interrupt.
12-Gauge
Blue Wire:
Ignition Output
Connection Required
.
Connect the Blue wire to the vehicle's Ignition wire
(also known as “Primary Ignition”). This wire will show +12 Volts when the igni-
tion key is in the "Run" and "Start" positions and no voltage in the "Off" and
"Accessory" positions. This wire is found in the ignition switch wiring harness
(see diagram on previous page).
Note: If two or more Primary Ignition wires are present, you will need to connect
an optional relay or relays to the 3-pin Red port (see pages 33-34).
