Holy cow, a whole book. I'm busy this weekend...can't read no stinking
book. Hey Will, you probably have a bad diode pack. Replace the alternator
and see.
Ron
00 PB SLT QC 4X2 5.9 46RE 3.92 LSD
For modifications see my DML Profile (URL follows)
http://www.twistedbits.net/WWWProfile/dakota/Kw9pV1EkFeOYY
-----Original Message-----
From: owner-dakota-truck@buffnet.net
[mailto:owner-dakota-truck@buffnet.net]On Behalf Of Bernd D. Ratsch
Sent: Friday, April 06, 2001 5:28 PM
To: dakota-truck@buffnet.net
Subject: RE: DML: GEN light question - Really long testing procedures
Alternator:
Denso Part # 56027913
Rated SAE Amps = 136
Minimum Test Amps = 120
Troubleshooting Tests
Before beginning any tests on a vehicle's electrical system, use the wiring
diagrams to study the circuit. Also refer to Troubleshooting Wiring
Problems.
Testing For Voltage
Connect the ground lead of a voltmeter to a known good ground.
Connect the other lead of the voltmeter to the selected test point. The
vehicle ignition may need to be turned ON to check voltage. Refer to the
appropriate test procedure.
Testing For Continuity
Testing For Continuity
Remove the fuse for the circuit being checked or disconnect the battery.
Connect one lead of the ohmmeter to one side of the circuit being tested.
Connect the other lead to the other end of the circuit being tested. Low or
no resistance means good continuity.
Testing For A Short To Ground
Remove the fuse and disconnect all items involved with the fuse.
Connect a test light or a voltmeter across the terminals of the fuse.
Starting at the fuse block, wiggle the wiring harness every 6 to 8 Inches
and watch the voltmeter/test light.
If the voltmeter registers voltage or the test light glows, there is a
short-to-ground in that general area of the wiring harness.
Testing For A Short-to-ground On Fuses Powering Several Loads
Refer to the wiring diagrams and disconnect or isolate all items on the fuse
circuit.
Replace the blown fuse.
Supply power to the fuse by turning ON the ignition switch or re-connecting
the battery.
Start connecting the items in the fuse circuit, one at a time. When the fuse
blows, the circuit with the short-to-ground has been isolated.
Testing For Voltage Drop
Connect the positive lead of the voltmeter to the side of the circuit
closest to the battery.
Connect the other lead of the voltmeter to the other side of the switch or
component.
Operate the item.
The voltmeter will show the difference in voltage between the two points.
Intermittent and Poor Connections
Most intermittent electrical problems are caused by faulty electrical
connections or wiring. It is also possible for a sticking component or relay
to cause a problem. Before condemning a component or wiring assembly, check
the following items:
Connectors are fully seated.
Spread terminals, or terminal push-out.
Terminals in the wiring assembly are fully seated into the
connector/component and locked in position.
Dirt or corrosion on the terminals. Any amount of corrosion or dirt could
cause an intermittent problem.
Damaged connector/component casing exposing the item to dirt and moisture.
Wire insulation that has rubbed through, causing a short to ground.
Wire broken inside of the insulation.
Battery Temperature Sensor
The sensor is located under the battery and is attached to the battery tray.
A two-wire pigtail harness is attached directly to the sensor. The opposite
end of this harness connects the sensor to the engine wiring harness.
Disconnect the two-wire pigtail harness from the engine harness.
Attach ohmmeter leads to the wire terminals of the pigtail harness.
At room temperature of 25 ?C (75 - 80 ?F) , an ohmmeter reading of 9,000
(9K) to 11,000 (11K) ohms should be observed.
If reading is above or below the specification, replace the sensor.
Refer to the Removal and Installation for procedures.
Voltage Signal - PCM Operation
PURPOSE
The engine controller continuously monitors battery voltage inputs, and
since battery voltage always fluctuates, the engine controller will
constantly be making changes to the injector pulse width and alternator
field.
OPERATION
The engine controller monitors battery voltage to determine the proper
injector pulse width and to control the alternator field voltage. If the
engine controller sees low battery voltage, it will increase the injector
pulse width to compensate for lack of voltage which could cause a lean
air/fuel mixture.
A higher voltage signal will be sent to the alternator field so that the
alternator will increase its charging output to the battery. When the
alternator increases its charging rate it will bring the battery up to its
normal state of charge.
Once the battery is fully charged, the engine controller reduces the
injector pulse width so that the air/fuel mixture doesn't go excessively
rich.
Voltage Regulator:
SYSTEM OPERATION
The Electronic Voltage Regulator (EVR) is not a separate component. It is
actually a voltage regulating circuit located within the Powertrain Control
Module (PCM) . The EVR is not serviced separately. If replacement is
necessary, the PCM must be replaced.
Operation: The amount of DC current produced by the generator is controlled
by EVR circuitry contained within the PCM. This circuitry is connected in
series with the generators second rotor field terminal and its ground.
Voltage is regulated by cycling the ground path to control the strength of
the rotor magnetic field. The EVR circuitry monitors system line voltage and
battery temperature (refer to Battery Temperature Sensor for more
information). It then compensates and regulates generator current output
accordingly Also see Charging System Operation for additional information.
- Bernd
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