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• Close the relay and probe at the solenoid.
voltage; open is further down the circuit than the solenoid.
no voltage; open is between relay and solenoid (point C).
Any powered circuit can be diagnosed using the approach in the previous example.
Testing for “Shorts” in the Circuit To simplify the discussion of shorts in the system, please refer to the following schematic.
RESISTANCE CHECK METHOD
• Disconnect the battery negative cable and remove the blown fuse.
• Disconnect all loads (SW1 open, relay disconnected and solenoid disconnected) powered through the fuse.
• Connect one probe of the DMM to the load side of the fuse terminal. Connect the other probe to a known
good ground.
• With SW1 open, check for continuity.
continuity; short is between fuse terminal and SW1 (point A).
no continuity; short is further down the circuit than SW1.
• Close SW1 and disconnect the relay. Put probes at the load side of fuse terminal and a known good ground.
Then, check for continuity.
continuity; short is between SW1 and the relay (point B).
no continuity; short is further down the circuit than the relay.
• Close SW1 and jump the relay contacts with jumper wir e. Put probes at the load side of fuse terminal and a
known good ground. Then, check for continuity.
continuity; short is between relay and solenoid (point C).
no continuity; check solenoid, retrace steps.
VOLTAGE CHECK METHOD
• Remove the blown fuse and disconnect all loads (i .e. SW1 open, relay disconnected and solenoid discon-
nected) powered through the fuse.
• Turn the ignition key to the ON or START position. Veri fy battery voltage at the battery + side of the fuse ter-
minal (one lead on the battery + terminal side of the fuse block and one lead on a known good ground).
• With SW1 open and the DMM leads across both fuse terminals, check for voltage.
voltage; short is between fuse block and SW1 (point A).
no voltage; short is further down the circuit than SW1.
• With SW1 closed, relay and solenoid disconnected and t he 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.
• 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 Ground connections are very important to the proper oper ation of electrical and electronic circuits. Ground
connections are often exposed to moisture, dirt and other corrosive elements. The corrosion (rust) can
become an unwanted resistance. This unwanted re sistance can change the way a circuit works.
Electronically controlled circuits are very sensitive to proper grounding. A loose or corroded ground can drasti-
cally affect an electronically controlled circuit. A poor or corroded ground can easily 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:
• Remove the ground bolt or screw.
• Inspect all mating surfaces for tarnish, dirt, rust, etc.
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BATTERY
How to Handle Battery INFOID:0000000004306818
CAUTION:
• If it becomes necessary to start the engine with a booster battery and jumper cables, use a 12-volt
booster battery.
• After connecting battery cables, ensure that they are tightly clamped to battery terminals for good
contact.
• Never add distilled water through the hole used to check specific gravity.
METHODS OF PREVENTING OVER-DISCHARGE The following precautions must be taken to prevent over-discharging
a battery.
• The battery surface (particularly its top) should always be kept clean and dry.
• The terminal connections should be clean and tight.
• At every routine maintenance, check the electrolyte level. This also applies to batteries designated as “low maintenance” and
“maintenance-free”.
• When the vehicle is not going to be used over a long period of time, disconnect the negative battery terminal.
• Check the charge condition of the battery. Periodically check the specific gr avity of the electrolyte. Keep a
close check on charge condition to prevent over-discharge.
CHECKING ELECTROLYTE LEVEL WARNING:
Do not allow battery fluid to come in contact with skin, eyes, fabrics, or painted surfaces. After touch-
ing a battery, do not touch or rub your eyes until yo u have thoroughly washed your hands. If acid con-
tacts eyes, skin or clothing, imme diately flush with water for 15 minutes and seek medical attention. MEL041F
