Download Symptom Chart

AT 121 Chapter 13a – Charging Systems
Name: _________________________________
Group: _________________________
Date: __________________________________
Symptom Chart
Condition
Charging system malfunction (high or low
system voltage)
Dead battery or battery will not stay charged
Charging system warning indicator
malfunctioning (light on with engine running,
light off with key on engine off, light on with key
off)
Generator is noisy
Radio interference
Possible Sources

A circuit fuse link.

B+ circuit fuse links.

Generator.

PCM/Regulator

Loose/Damaged Drive Belt

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




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
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


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Defective Generator.
Defective Battery.
B+ Circuit.
High key-off load. (Parasitic Drain)
Loose, corroded terminal(s).
Charging system warning indicator bulb.
Instrument cluster.
Generator.
PCM/Regulator
Loose bolts/brackets.
Drive belt.
Generator Bearings
Generator.
Wiring/routing - poor grounds
In-vehicle entertainment system.
Tools you will need:
Given Vehicle
ARBST Tester
Amp Probe
 SECTION 1 Inspect Accessory Drive Belt Condition and
Tension.
Incorrect belt tension will cause undercharging. A loose belt will slip and squeal.
An over tightened belt will cause will cause bearing damage. An oily belt will slip, but
be quiet. Misaligned drive belts will cause fraying and constantly be “thrown off”.
 Is there oil on the belt? _________________________ (Yes/No)
 Drive the belt show signs of chunking? ________________ (Yes/No)
 Are the pulleys in alignment? ______________________ (Yes/No)
 Is the accessory drive belt OK? __________________ (Yes/No)
 SECTION 2 Check Generator Connections
Poor generator connections will cause high resistance in the B+ circuit. This will cause a voltage drop.
 Are the generator connections (B+, Ground, and Regulator Connections) clean and tight? __________________ (Yes/No)
Be sure to properly torque all fittings on the alternator! A loose fitting will arc, causing high heat and possible fire!
NEVER run a vehicle with a poorly grounded alternator. Severe voltage spikes may occur and damage electronic
components.
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 SECTION 3 Charging System Voltage
 With the engine running, monitor the voltage at the battery.
 Is the battery voltage between 13 and 15 volts? __________ (Yes/No)
 What is the battery voltage? ____________________
 When finished have the instructor sign off on your work. _____________________________________
 SECTION 4 Voltage Drop Tests
Output Circuit – Insulated (Power) Side
 Place one end of the meter at the B+ terminal of the
alternator.
 Place the other end of the meter at the (+) terminal of the
battery.
 Run the vehicle with no loads at 2000 rpm
 The voltage drop should be less than 0.5 volts.
The voltage drop is _______________________
 If the voltage drop were greater than 0.5 volts this would
indicate high resistance in the B+ circuit of the alternator. A
corroded wire or terminal end could be the cause.
Output Circuit – Ground Side
 Place one end of the meter at the case of the alternator.
 Place the other end of the meter at the (-) terminal of the
battery.
 Run the vehicle with no loads at 2000 rpm
 The voltage drop should be less than 0.2 volts.
 The voltage drop is _______________________
If the voltage drop were greater than 0.2 volts this would
indicate high resistance in the ground circuit of the alternator.
A corroded wire or terminal end could be the cause as well as a
poor engine ground or loose alternator mount.
 SECTION 5 Checking for Diode Ripple (AC voltage) (no, not THAT Ripple!)
 Checking Ripple Voltage Ripple voltage or (AC voltage) can be measured by switching the DVOM to AC and connecting
the black lead to a good ground and the red lead to the B+ on the back of the alternator.
 A good alternator should measure less than .5 VAC with the engine running. A higher reading indicates damaged
alternator diodes.
Voltage A/C __________________
Pass/Fail? _________________________
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Q
At what RPM should the voltage drop tests be done at? __________________________
A voltage drop of more than ____________________ indicates high resistance in the B+ circuit.
A voltage drop of more than ____________________ indicates high resistance in the ground circuit.
When checking for AC diode ripple, if the AC voltage is more than _______________ volts ___________ the diodes in the
alternator may have failed.
What will be the end result of an over tightened belt? _______________________________________
What would cause the belt to slip, even if it were tight? _______________________________________
When would one hear a loose alternator belt? _____________________________________________
Name 5 things that would cause a generator to undercharge:
___________________________________________________________________________________________________
___________________________________________________________________________________________________
 When finished have the instructor sign off on your work. _____________________________________
 SECTION 6 Alternator Load Testing
Tools you will need:
2001 Honda Accord (70 amp Alternator)
ARBST Tester
Amp Probe
Following the procedure demonstrated to you by the instructor test the alternator using the ARBST tester.
ARBST Tester Results;
Volts _____________________
Amps ______________________ Diodes ___________________
 Leaving the ARBST tester hooked up. With the engine running, turn the A/C on, the blower motor on high speed, rear
defroster on, and the headlamps on high beam. Increase the engine speed to approximately 2,000-rpm. The voltage should
increase a minimum of 0.5 volt above the base voltage.
The total amps should be close to the maximum of the alternator total output. Fact is this test can be done with any
inductive amp meter.
Volts _____________________
Amps ______________________
If voltage were low – the next step would be to full field the alternator.
Full Fielding the Alternator

WARNING! DO NOT FULL FIELD ALTERNATOR FOR MORE THAN 10 SECONDS AT A TIME!
 Ground the “F” terminal
Results - Volts _____________________
This test bypasses the regulator and sends full field voltage and current to the rotor assembly. Voltage should be about
17-18 volts. If not a damaged rotor or stator is possible. If voltage DOES go up, but falls back to a voltage lower than 13
volts – the regulator is bad.
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 SECTION 7 Generator Removal and Installation
Alternator Removal:
Jetta 2.0 BBW Gasoline Engine
1 - Tensioner
2 - Bracket
3 - Hex socket bolts
M10 x 45mm - 45 Nm
4 - Screws
5 – D Terminal - Nut
M8 – 3Nm
6 – B+ Terminal - Nut
M8 – 3Nm
7 - Screw
8 - Voltage Regulator (VR)
Removing and installing. Refer to Voltage Regulator
(VR), removing and installing
Checking carbon brushes. Refer to Generator (GEN)
carbon brushes, checking
9 - Protective cap
10 - Generator (GEN)
11 - Ribbed belt
12 - Hex bolts
M8 x 85mm - 25 Nm
13 - Hex bolts
M8 x 45mm - 25 Nm
Ribbed belt routing
1 - Tensioning roller
2 - Pulley - generator (GEN)
3 - Pulley - a/c compressor
4 - Ribbed belt - generator, a/c compressor, power steering
pump and crankshaft/vibration damper
5 - Pulley - power steering pump
6 - Pulley - crankshaft/vibration damper
CAUTION: Before removing ribbed belt, mark direction of
rotation. Belt damage will result if not reinstalled in proper
direction. Check ribbed belt. Always replace ribbed belt if
found to be damaged. This will avoid related failures or
operating problems.
Mark direction of rotation of ribbed belt if it is to be reused.
1 - Loosen ribbed belt by turning tensioner in direction of -arrow-.
2 - Block Tensioner With Pin, Lock, or Punch
3 - Remove ribbed belt.
4 - Remove Alternator.
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Once the alternator has been reinstalled on the vehicle. Verify its operation using the Midtronics tester:
Install the Midtronics tester to the battery.
Select Automotive Charging System Test.
Once the test is started, follow the prompts:
1. Rev the engine.
2. Turn on high beams headlights and the blower fan.
3. Rev engine with loads on.
4. Idle engine and turn off loads.
5. The Charging System decision is displayed at the end of the procedure.
Test Results? _________________________________________________________
Using the following diagram, indicate where and how you would test for a B+ voltage drop test, and a groundside voltage
drop test
 SECTION 8 Testing for radio interference
Tune the radio to a station where the interference is present (640 AM)
Is the interference present with the generator regulator (D wire) disconnected? ________________ (Yes/No)
If the noise goes away a new generator is needed due to a bad diode assembly or damaged stator or rotor. If the noise
is still present it may be an ignition system malfunction or a poor ground on the audio system
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Proper Charging Voltage would be;
A.
B.
C.
D.
12.5 – 13.6 V
13.5 – 15.5 V
14.5 – 16 V
15.5 – 17.2 V
The drive belt must be;
A.
B.
C.
D.
The Stationary Component is the;
A.
B.
C.
D.
Slip Rings
Rotor
Fan
Stator
The Moving Component is the;
A.
B.
C.
D.
Regulator
Rotor
Brushes
Stator
Current is sent into the _____________ from the
regulator; this can increase or decrease the output
of the _______________
A.
B.
C.
D.
Bearings, Case
Stator, Brushes
Rotor, Stator
Stator, Rotor
The _________ allows contact between the rotor
and the regular and battery;
A.
B.
C.
D.
Bearings
Case Mount
Brushes
Stator
The pulley must:
A.
B.
C.
D.
Have the correct number of grooves
Be loose
Be not aligned with the other accessory
drive units
Be press fit
Have the correct number of grooves
Very tight so it does not slip
Very loose so as not to damage the
bearings in the alternator
Oily so it slides nicely over the pulley
grooves
Diodes
A.
B.
C.
D.
Convert DC into AC
Convert AC into DC
Do not get hot
Do not exist in the alternator
The ___________ monitors battery voltage
A.
B.
C.
D.
Rotor
Stator
Regulator
Brushes
Voltage regulators can be controlled by;
A.
B.
C.
D.
The PCM
A transistor
A relay
All of the above
A screeching sound is heard right after startup;
A.
B.
C.
D.
The alternator belt is too tight
The alternator belt has oil on it
The alternator belt is too loose
The alternator bearings are bad
The charge lamp
A.
B.
C.
D.
Will be on when the vehicle is at KOEO
Will be on when the vehicle is at KOER
Will be on when the vehicle is overcharging
Will be on when the vehicle is off
The charge lamp does not operate, what is the
most likely cause?
A.
B.
C.
D.
Grounded bulb circuit in regulator
Loose belt
Burned out bulb
Over charged battery
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