4)
With SW1 closed, relay and solenoid disconnected and the
DMM leads across both fuse terminals, check for voltage.
voltage; short is between SW1 and the relay (point B).
no voltage; short is further down the circuit than the relay.
5)
With SW1 closed, relay contacts jumped with fused jumper
wire check for voltage.
voltage; short is down the circuit of the relay or between the
relay and the disconnected solenoid (point C).
no voltage; retrace steps and check power to fuse block.
GROUND INSPECTION
NHGI0005S0304
Ground connections are very important to the proper operation of
electrical and electronic circuits. Ground connections are often
exposed to moisture, dirt and other corrosive elements. The corro-
sion (rust) can become an unwanted resistance. This unwanted
resistance can change the way a circuit works.
Electronically controlled circuits are very sensitive to proper
grounding. A loose or corroded ground can drastically affect an
electronically controlled circuit. A poor or corroded ground can eas-
ily affect the circuit. Even when the ground connection looks clean,
there can be a thin film of rust on the surface.
When inspecting a ground connection follow these rules:
1)
Remove the ground bolt or screw.
2)
Inspect all mating surfaces for tarnish, dirt, rust, etc.
3)
Clean as required to assure good contact.
4)
Reinstall bolt or screw securely.
5)
Inspect for “add-on” accessories which may be interfering with
the ground circuit.
6)
If several wires are crimped into one ground eyelet terminal,
check for proper crimps. Make sure all of the wires are clean,
securely fastened and providing a good ground path. If multiple
wires are cased in one eyelet make sure no ground wires have
excess wire insulation.
SGI853
VOLTAGE DROP TESTS
NHGI0005S0305
Voltage drop tests are often used to find components or circuits
which have excessive resistance. A voltage drop in a circuit is
caused by a resistance when the circuit is in operation.
Check the wire in the illustration. When measuring resistance with
MA
EM
LC
EC
FE
AT
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
HOW TO PERFORM EFFICIENT DIAGNOSIS FOR AN ELECTRICAL INCIDENT
Circuit Inspection (Cont’d)
GI-31