Liquid Controls DMS Installation - Manual (Page 11)

11
GroundInG The dMs
GroundInG The TruCk seaT
Static electricity can build up on truck seats and the
drivers themselves, especially during cold, dry weather.
Adjustable, shock-absorbing seats are especially vulner-
able because they isolate the seat cushion from an elec-
trical ground. If electrostatic discharge (ESD) occurs on
or near the DMS, the truck’s electrical system, its compo-
nents, and the DMS are all susceptible to damage.
To prevent the ocurrence of electrostatic discharge, it
is mandatory that installers properly ground the truck
seat(s). Properly grounded seats allow static electricity to
“bleed off” the driver and the seat before it can build up,
discharge, and interfere with the operation of the DMS or
other truck components.
GroundInG
Ground the seat:
1. Locate a good ground point near the back of the seat
frame. The bottom of the seat base is usually a good
spot.
2. Drill a 9/32” hole in the seat frame near the back of the
base.
3. Attach one end of the ground strap to the seat frame
bracket using the lock washer, flat washer, and nut
provided. The lock washer should penetrate any paint on
the bracket to ensure a good electrical connection.
4. Attach the other end of the strap to a metal part of the
seat frame at a point where it contacts the seat cushion.
Make sure that there are no intervening pivot points,
guides, adjustment mechanisms, etc., which could
interfere with the ground path between the seat cushion
and the ground strap.
5. If the seat cushion has a wooden base, use a wood
screw and washer to attach the strap lug to the bottom
of the seat at a point where the seat fabric is attached to
the wood. There must be good contact between the seat
fabric and ground strap lug.
6. Make sure the strap is positioned so that it doesn’t
interfere with the movement of the seat and it is clear of
traffic areas in the cab.
7. Check the strap for a good ground connection.
Check for a good ground connection along the
ground strap:
1. Turn off all accessories, including the dome light, to
prevent other currents from distorting the reading.
2. Take a multimeter and measure the resistance between
the brackets the ground strap bolts are fastened to.
Find a clean spot on the brackets without paint to use
as contact points. Other bolts on the brackets are often
suitable.
2a. If the resistance is less than 3Ω, the system is grounded
adequately.
2b. If the resistance is still greater than 3Ω, check for proper
metal to metal contact on both ends of the grounding
strap. Clean any paint, dirt, or oxidation that may block
the grounding point. If the resistance remains above
3Ω, attach the ground strap to a different ground point.
Repeat the process until the ground resistance is below
3Ω.
If the truck has two seats, ground both seats. To
ground a second seat, another Ground Strap Kit (PN#
82180) must be ordered from LC.
Preserve the integrity of cables and their connections to the
components. Bind them together with electrical tape, zip ties,
or another fastener, and loop the cables around the mount
(or another secure support). This will prevent any tugging
on the connections if the cables are stepped on or pulled
inadvertently.
Two Truck Seats
Power and Data Cables