1993 VOLKSWAGEN CORRADO display

SPECIFICATIONS & ELECTRIC COOLING FANS
Article Text (p. 2)
1993 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Wednesday, March 22, 2000 09:23PM
fan is not coming on at proper temperature and engine is
overheating.
Corrado SLC, Passat GLX
The cooling fan is either a 1 or 2-speed motor. If vehicle is
equipped with single-speed motor, the fan comes on at 198-207øF (92-
97
øC) and turns off at 183-196øF (84-91øC). If equipped with a 2-speed
motor, low speed of cooling fan should come on at 198-208
øF (92-98øC)
on vehicles without A/C, or 183-207
øF (84-97øC) on vehicles with A/C.
Low speed will shut off at 183-196
øF (84-91øC) on all vehicles. High
speed comes on at 210-226
øF (99-108øC) on vehicles without A/C, or
201-226
øF (94-108øC) on vehicles with A/C. High speed will shut off at
196-220
øF (91-104øC) on all vehicles.
After-Run Thermoswitch
An after-run switch is used to help prevent fuel
vaporization. The thermoswitch turns cooling fan on when temperatures
in engine compartment exceeds 230
øF (110øC), and turns it off at 217øF
(103
øC).
Passat GL
The cooling fan is a 2-speed motor. Low speed of cooling fan
should come on at 198-207
øF (92-97øC) and will shut off at 183-196øF
(84-91
øC). High speed comes on at 210-221øF (99-105øC) and will shut
off at 196-208
øF (91-98øC).
TROUBLE SHOOTING
NOTE: Trouble shooting information not available from manufacturer.
TESTING
ENGINE COOLANT TEMPERATURE (ECT) SENSOR
Corrado SLC & Passat GLX (2.8L)
1) Ensure engine is cold. Connect Scan Tester (VAG 1551) to
Data Link Connectors (DLC) located in center console, in front of
shift lever.
2) Start engine and allow it to idle. With scan tester in
READ TEST VALUE BLOCK function, select group No. 01 and read coolant
temperature value in field No. 2 of scan tester. Temperature value
must increase uniformly without interruption. If value increases as
specified, select END OUTPUT function on scan tester.
3) If displayed value does not change or if engine
malfunctions during certain temperature ranges, turn ignition off and
measure engine coolant temperature sensor resistance. See ECT SENSOR
LOCATION table. Replace ECT sensor if resistance is not within
specification. See ECT SENSOR RESISTANCE table.
Passat GL
1) Ensure engine is cold. Connect Scan Tester (VAG 1551) to
Data Link Connectors (DLC) located in center console. Start engine and

SPECIFICATIONS & ELECTRIC COOLING FANS
Article Text (p. 3)
1993 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Wednesday, March 22, 2000 09:23PM
allow it to idle. With scan tester in READ MEASUREMENT BLOCK function,
read coolant temperature value in channel No. 1 of scan tester.
2) If temperature value increases uniformly without
interruption, sensor and its circuit are okay. Select END OUTPUT
function on scan tester. If display value is incorrect, test wiring
harness for open or short circuit. See Corrado SLC WIRING DIAGRAMS,
or Passat WIRING DIAGRAMS articles.
3) If necessary, use test leads from Adapter Kit (VAG 1594)
to measure ECT sensor resistance. See ECT SENSOR LOCATION table.
Replace engine coolant temperature sensor if not within specification.
See ECT SENSOR RESISTANCE table.
ECT SENSOR RESISTANCE TABLEÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄTemperature
øF (øC) Ohms
68 (20) ........................................ 3000-2000
86 (30) ........................................ 2000-1500
104 (40) ....................................... 1500-1000
122 (50) ........................................ 1000-800
140 (60) ......................................... 700-500
158 (70) ......................................... 500-375
176 (80) ......................................... 375-275
194 (90) ......................................... 275-225
ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄECT SENSOR LOCATION TABLE
ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄModel Location
Corrado SLC & Passat GLX
Blue, Brown & Yellow Sensor . On Radiator Near Upper Hose
Passat GL .............................. Below Distributor
ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄEND OF ARTICLE

TROUBLE SHOOTING - BASIC PROCEDURES
Article Text (p. 22)
1993 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Wednesday, March 22, 2000 09:26PM
as heard. Extra differential thrust washers installed during axle
repair can cause a condition of partial lock-up that creates this
chatter.
AXLE SHAFT NOISE
Axle shaft noise is similar to gear noise and pinion bearing
whine. Axle shaft bearing noise will normally distinguish itself from
gear noise by occurring in all driving modes (Drive, cruise, coast and
float), and will persist with transmission in Neutral while vehicle is
moving at problem speed.
If vehicle displays this noise condition, remove suspect
axle shafts, replace wheel seals and install a new set of bearings.
Re-evaluate vehicle for noise before removing any internal components.
VIBRATION
Vibration is a high-frequency trembling, shaking or grinding
condition (felt or heard) that may be constant or variable in level
and can occur during the total operating speed range of the vehicle.
The types of vibrations that can be felt in the vehicle can
be divided into 3 main groups:
* Vibrations of various unbalanced rotating parts of the
vehicle.
* Resonance vibrations of the body and frame structures caused
by rotating of unbalanced parts.
* Tip-in moans of resonance vibrations from stressed engine or
exhaust system mounts or driveline flexing modes.
DRIVE AXLE - RWD TROUBLE SHOOTING
WARNING: This is GENERAL information. This article is not intended
to be specific to any unique situation or individual vehicle
configuration. The purpose of this Trouble Shooting
information is to provide a list of common causes to
problem symptoms. For model-specific Trouble Shooting,
refer to SUBJECT, DIAGNOSTIC, or TESTING articles available
in the section(s) you are accessing. For definitions
of listed noises or sounds, see DRIVE AXLE - NOISE DIAGNOSIS.
DRIVE AXLE (RWD) TROUBLE SHOOTINGÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄCONDITION POSSIBLE CAUSE CORRECTION
ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄKnocking or Clunking
Differential Side Gear
Clearance Check Clearance
Worn Pinion Shaft Replace Pinion Shaft
Axle Shaft End Play Check End Play

WAVEFORMS - INJECTOR PATTERN TUTORIAL
Article Text (p. 4)
1993 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Wednesday, March 22, 2000 09:26PM
In any cases of doubt regarding the use of a noid light, a
lab scope will overcome all inherent weaknesses.
OVERVIEW OF DVOM
A DVOM is typically used to check injector resistance and
available voltage at the injector. Some techs also use it check
injector on-time either with a built-in feature or by using the
dwell/duty function.
There are situations where the DVOM performs these checks
dependably, and other situations where it can deceive you. It is
important to be aware of these strengths and weaknesses. We will cover
the topics above in the following text.
Checking Injector Resistance
If a short in an injector coil winding is constant, an
ohmmeter will accurately identify the lower resistance. The same is
true with an open winding. Unfortunately, an intermittent short is an
exception. A faulty injector with an intermittent short will show
"good" if the ohmmeter cannot force the short to occur during testing.
Alcohol in fuel typically causes an intermittent short,
happening only when the injector coil is hot and loaded by a current
high enough to jump the air gap between two bare windings or to break
down any oxides that may have formed between them.
When you measure resistance with an ohmmeter, you are only
applying a small current of a few milliamps. This is nowhere near
enough to load the coil sufficiently to detect most problems. As a
result, most resistance checks identify intermittently shorted
injectors as being normal.
There are two methods to get around this limitation. The
first is to purchase an tool that checks injector coil windings under
full load. The Kent-Moore J-39021 is such a tool, though there are
others. The Kent-Moore costs around $240 at the time of this writing
and works on many different manufacturer's systems.
The second method is to use a lab scope. Remember, a lab
scope allows you to see the regular operation of a circuit in real
time. If an injector is having an short or intermittent short, the lab
scope will show it.
Checking Available Voltage At the Injector
Verifying a fuel injector has the proper voltage to operate
correctly is good diagnostic technique. Finding an open circuit on the
feed circuit like a broken wire or connector is an accurate check with
a DVOM. Unfortunately, finding an intermittent or excessive resistance
problem with a DVOM is unreliable.
Let's explore this drawback. Remember that a voltage drop due
to excessive resistance will only occur when a circuit is operating?
Since the injector circuit is only operating for a few milliseconds at
a time, a DVOM will only see a potential fault for a few milliseconds.
The remaining 90+% of the time the unloaded injector circuit will show
normal battery voltage.
Since DVOMs update their display roughly two to five times a

WAVEFORMS - INJECTOR PATTERN TUTORIAL
Article Text (p. 6)
1993 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Wednesday, March 22, 2000 09:26PM
cause inaccurate readings. This is because of a DVOM's slow display
rate; roughly two to five times a second. As we covered earlier,
measurements in between display updates get averaged. So conditions
like skipped injector pulses or intermittent long/short injector
pulses tend to get "averaged out", which will cause you to miss
important details.
The last limitation is that varying engine speeds can result
in inaccurate readings. This is caused by the quickly shifting
injector on-time as the engine load varies, or the RPM moves from a
state of acceleration to stabilization, or similar situations. It too
is caused by the averaging of all measurements in between DVOM display
periods. You can avoid this by checking on-time when there are no RPM
or load changes.
A lab scope allows you to overcome each one of these
limitations.
Checking Injector On-Time With Dwell Or Duty
If no tool is available to directly measure injector
millisecond on-time measurement, some techs use a simple DVOM dwell or
duty cycle functions as a replacement.
While this is an approach of last resort, it does provide
benefits. We will discuss the strengths and weaknesses in a moment,
but first we will look at how a duty cycle meter and dwell meter work.
How A Duty Cycle Meter and Dwell Meter Work
All readings are obtained by comparing how long something has
been OFF to how long it has been ON in a fixed time period. A dwell
meter and duty cycle meter actually come up with the same answers
using different scales. You can convert freely between them. See
RELATIONSHIP BETWEEN DWELL & DUTY CYCLE READINGS TABLE.
The DVOM display updates roughly one time a second, although
some DVOMs can be a little faster or slower. All measurements during
this update period are tallied inside the DVOM as ON time or OFF time,
and then the total ratio is displayed as either a percentage (duty
cycle) or degrees (dwell meter).
For example, let's say a DVOM had an update rate of exactly 1
second (1000 milliseconds). Let's also say that it has been
measuring/tallying an injector circuit that had been ON a total of 250
mS out of the 1000 mS. That is a ratio of one-quarter, which would be
displayed as 25% duty cycle or 15ø dwell (six-cylinder scale). Note
that most duty cycle meters can reverse the readings by selecting the
positive or negative slope to trigger on. If this reading were
reversed, a duty cycle meter would display 75%.
Strengths of Dwell/Duty Meter
The obvious strength of a dwell/duty meter is that you can
compare injector on-time against a known-good reading. This is the
only practical way to use a dwell/duty meter, but requires you to have
known-good values to compare against.
Another strength is that you can roughly convert injector mS
on-time into dwell reading with some computations.
A final strength is that because the meter averages