Electrical Service Diagnosis - Truck

Symptoms Probable Remedy
Battery Discharged:
Shorted Cell in Battery Replace Battery
Short in Wiring Check Wiring Circuit
Generator Not Charging Inspect Generator and Fan Belt
Loose or Dirty Terminals Clean and Tighten
Excessive Use of Starter Tune Engine
Excessive Use of Lights Check Battery
Insufficient Driving Recharge Battery
Low Regulator Setting Correct Setting
Stuck Cut-out in Regulator Correct
Low Electrolyte Level in Cells Add Distilled Water
Generator:
Low Charging Rate-
Dirty Commutator Clean Commutator
Poor Brush Contact Repair or Install New Brushes
Regulator Improperly Adjusted Adjust
High Resistance in Charging Circuit Clean and Tighten Terminals
Ground Strap Engine to Frame Broken Replace
Loose or Dirty Terminals Clean and Tighten
Slipping Generator Belt Adjust Belt
Worn Out Brushes Install New Brushes
Weak Brush Spring Tension Replace
Out of Round Commutator Repair
Fails to Charge-
Open Charging Circuit Correct
Sticking Brushes Repair or Replace
Dirty or Burned Commutator Clean Commutator
Grounded Commutator Repair
Open Circuit in Field Repair
Weak Soldering on Armature Repair
Grounded Wiring Repair
Defective Regulator Replace Regulator
Too High Charging Rate-
Regulator Improperly Adjusted Adjust or Replace
Short in Armature Replace
Grounded Field-to-regulator Wire Correct
Shorted Cell in Battery Replace Battery
Starting Motor:
Slow Starter Speed-
Discharged Battery or Shorted Cell Recharge or Repair
Ground Strap Engine to Frame Clean Terminals and Tighten
Loose or Dirty Terminals Clean and Tighten
Dirty Commutator Clean with No. 00 Sandpaper
Worn Out Brushes Install New Brushes
Weak Brush Spring Tension Replace
Poor Brush Contact Repair or Install New Brushes
Worn Bearings Replace
Burned Starter Switch Contacts Replace Switch
Will Not Turn Engine-
Open Circuit at Starter Correct
Solenoid Open or Stuck Replace Solenoid
Starter Switch Defective Replace Switch
Starter Drive Broken or Stuck Repair or Replace
Battery Discharged Recharge Battery
Distributor:
Hard Starting-
Distributor Points Burned or Pitted Clean Points or Replace (Adjust)
Breaker Arm Stuck on Pivot Pin Clean and Lubricate
Breaker Arm Spring Weak Replace
Points Improperly Adjusted Adjust .020"
Spark Plug Points Improperly Set Adjust .030"
Spark Plug Wire Terminals in Distributor Cap Corroded Clean
Loose Terminals Check Circuit
Loose or Dirty Terminals on Ground Strap Engine to Frame Clean and Tighten
Condenser Faulty Replace
Improper Ignition Timing Set Timing
Distributor:
Hard Starting-
Distributor Points Burned or Pitted Clean Points or Replace (Adjust)
Breaker Arm Stuck on Pivot Pin Clean and Lubricate
Breaker Arm Spring Weak Replace
Points Improperly Adjusted Adjust .020"
Spark Plug Points Improperly Set Adjust .030"
Spark Plug Wire Terminals in Distributor Cap Corroded Clean
Loose Terminals Check Circuit
Loose or Dirty Terminals on Ground Strap Engine to Frame Clean and Tighten
Condenser Faulty Replace
Improper Ignition Timing Set Timing
Lights:
Burn Dim-
Loose or Dirty Terminals Clean and Tighten
Leak in Wires Check Entire Circuit for Broken Insulation
Poor Switch Contact Install New Switch
Poor Ground Connection Clean and Tighten
Aim Headlamp Beams Use Aiming Chart
Horn Fails to Sound
Broken or Loose Electrical Connection Check Wiring and Connections at Horn Button and Battery-Clean and Tighten.
Battery Low or Dead Check Battery.
Contact Points Burned or Broken Off Replace Parts Necessary.
Horn Sounds Unsatisfactory Tone
Poor Electrical Connection Check Connections at Horn, Horn Button, Battery.
Battery Low Check with Hydrometer.
Loose Cover and Bracket Screws Tighten Bracket Bolts at Horn.
Voltage at Horn too High or too Low Check with Voltmeter.

* Learn more about electrical from the Service Manual for Jeep Utility Vehicles, pages 149, 150

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