Voltage Drop Test - Jeep 1997 Grand Cherokee Service Manual

ZG
DIAGNOSIS AND TESTING (Continued)
reading now becomes very low or non-existent, refer
to Group 8C - Charging System to diagnose the
faulty charging system. After the high-amperage IOD
has been corrected, switch the multi-meter to pro-
gressively lower amperage scales and, if necessary,
repeat the fuse and circuit breaker removal process
to identify and correct the sources of excessive IOD.
It is now safe to select the lowest milliampere scale
of the multi-meter to check the low-amperage IOD.
CAUTION: Do not open any doors, or turn on any
electrical accessories with the lowest milliampere
scale selected, or the multi-meter may be damaged.
(6) Observe the multi-meter reading. The low-am-
perage IOD should not exceed thirty milliamperes
(0.030 ampere). If the draw exceeds thirty milliam-
peres, isolate each circuit by removing the circuit
breakers and fuses. The multi-meter reading will
drop to within the acceptable limit when the source
of the excessive draw is disconnected. Repair this cir-
cuit as required; whether a wiring short, incorrect
switch adjustment, or a component failure is at fault.

VOLTAGE DROP TEST

The voltage drop test will determine if there is
excessive resistance in the battery terminal connec-
tions or the battery cables. When performing these
tests, it is important to remember that the voltage
drop is giving an indication of the resistance between
the two points at which the voltmeter probes are
attached.
Example: When testing the resistance of the bat-
tery positive cable, touch the voltmeter leads to the
battery positive cable clamp and the cable connector
at the starter solenoid. If you probe the battery pos-
itive terminal post and the cable connector at the
starter solenoid, you are reading the combined volt-
age drop in the battery positive cable clamp-to-termi-
nal post connection and the battery positive cable.
WARNING:
•
IF THE BATTERY SHOWS SIGNS OF FREEZ-
ING, LEAKING, LOOSE POSTS, OR LOW ELECTRO-
LYTE LEVEL, DO NOT TEST, ASSIST-BOOST, OR
CHARGE. THE BATTERY MAY ARC INTERNALLY
AND EXPLODE. PERSONAL INJURY AND/OR VEHI-
CLE DAMAGE MAY RESULT.
• EXPLOSIVE HYDROGEN GAS FORMS IN AND
AROUND THE BATTERY. DO NOT SMOKE, USE
FLAME, OR CREATE SPARKS NEAR THE BATTERY.
PERSONAL INJURY AND/OR VEHICLE DAMAGE
MAY RESULT.
•
THE BATTERY CONTAINS SULFURIC ACID,
WHICH IS POISONOUS AND CAUSTIC. AVOID CON-
TACT WITH THE SKIN, EYES, OR CLOTHING. IN
THE EVENT OF CONTACT, FLUSH WITH WATER
FUEL GENERATOR SHUT-OFF FUEL INJECTOR PUMP FUEL SHUT-OFF SOLENOID CONNECTOR SOLENOID
AND CALL A PHYSICIAN IMMEDIATELY. KEEP OUT
OF THE REACH OF CHILDREN.
• IF THE BATTERY IS EQUIPPED WITH REMOV-
ABLE CELL CAPS, BE CERTAIN THAT EACH OF
THE CELL CAPS IS IN PLACE AND TIGHT BEFORE
THE BATTERY IS RETURNED TO SERVICE. PER-
SONAL INJURY AND/OR VEHICLE DAMAGE MAY
RESULT FROM LOOSE OR MISSING CELL CAPS.
The following operation will require a voltmeter
accurate to 1/10 (0.10) volt. Before performing the
tests, be certain the following procedures are accom-
plished:
• Battery is fully-charged as described in this
group.
• Fully engage the parking brake.
• If the vehicle is equipped with an automatic
transmission, place the gearshift selector lever in the
Park position. If the vehicle is equipped with a man-
ual transmission, place the gearshift selector lever in
the Neutral position and fully depress the clutch
pedal.
• Unplug the Automatic ShutDown (ASD) relay to
prevent a gasoline engine from starting. The ASD
relay is located in the Power Distribution Center
(PDC). Refer to the PDC label for ASD relay identi-
fication and location. To prevent a diesel engine from
starting, unplug the fuel shut off solenoid wire har-
ness connector (Fig. 10).
Fig. 10 Fuel Shut Off Solenoid Connector- Diesel
(1) Connect the positive lead of the voltmeter to
the battery negative terminal post. Connect the neg-
ative lead of the voltmeter to the battery negative
BATTERY
Engine
FWD
8A - 11