J&S Electronics
13925 Parkway Dr. Garden Grove, CA 92843
(714) 534-6975 www.jandssafeguard.com
AUTO
BRITE
MIN
MIN
RICH
LEAN
KNOCK RETARD
POWER
11.0:1
12.0:1
13.5:1
CRUISE
POWER
J&S ELECTRONICS
2.5 mm Plug
3.5 mm Plug
To SafeGuard Monitor Connector
O2 Signal
O2 Ground
Chassis Ground
(Bare Shield)
(Clear or Red)
(Black)
Operation
Two cables are supplied with the gauge. The cable with the two 3.5 mm plugs connects the retard display
to the SafeGuard, while the 2.5 mm shielded cable connects the O2 display to the O2 wires.
Conect the White wire of the shielded cable to O2 signal, the Black to O2 reference or ground, and the
bare shield wire to chassis ground. For one wire sensors, connect both the Black and the shield wires to
ECU ground.
Bargraph Test
The SafeGuard has software to test the retard display. On power-up, you will see the display march up and
back over a two second period. This tests the monitor, the cable, and the connector. It also verifies that
the software is up and running. The test is aborted if the key is moved to the start position.
Retard Display
The Retard Display shows how much timing is being taken out by the SafeGuard. When the SafeGuard is
set for 20° knock control range (mode switch #1 up), each LED is worth two degrees of retard. If the
SafeGuard is set for “Retard All” (mode switch #2 up), and it is taking out say, 12° of timing, then you would
see the 6th LED on. If the SafeGuard is set for “Retard Separate”, then the display becomes more
complex. Since the SafeGuard can retard each cylinder by a separate amount, you will see one LED on for
each cylinder that is being retarded, and the position of that LED indicates how far. For example, let
’
s say
that one cylinder is retarded 4°, another 6°, and another 8°, then you would see the 2nd, 3rd, and 4th
LED
’
s on. With the SafeGuard mode switch #1 down, these readings are cut in half.
Air/Fuel Ratio Display
The Air/Fuel section of the gauge will work with any standard O2 sensor, though it is calibrated for a Bosch
LSM-11 sensor, operating at 1450°F. The Air/Fuel ratio display reads the voltage produced by the O2
sensor. With the switch set to “Cruise” mode, the display reads from about 0.35v (lean) to about 096v
(rich). This mode is used to help you get the mixture in the ballpark. When the mode is switched to
“Power”, the display “zooms in” to the critical range of 0.81v to 0.90v for fine tuning.
PN 2002 Dual Monitor (optional)
