Testing with the impulse counter should be carried out for rapid fault diagnosis. The
impulse counter output shows only existing faults, since the ACC system does not have
memory capabilities. If one or more faults are indicated, repair as necessary and repeat
the test. Be sure that fuse #7 is good, the battery voltage is between 11-14 volts and the
temperature selector wheel is set to 22°C.
1. Connect the impulse counter to the on-board diagnostic connector.
Black lead of the impulse counter to socket 1
Yellow lead of the impulse counter to socket 7
Red lead of the impulse counter to battery positive terminal.
2. Turn the ignition to the "ON" position.
The LED "U Batt" will be illuminated. If the LED "U BATT" does not illuminate,
check for voltage between socket 1 of the on-board diagnostic connector and
the positive terminal of the battery. If the voltage is not between 11-14 volts,
check for an open circuit or loose ground connection.
Test for voltage between socket 7 and socket 1 of the diagnostic connector.
The voltage should be 6 - 12 volts.
3. Depress the start button for 2 - 4 seconds.
Fault codes will be indicated by the number in the impulse counter display
window. Take note of the impulse display number.
Faults are displayed in ascending order.
The number 1 indicates that no faults are stored in memory.
During the impulse readout, The LED indicator in the fresh air/recirculation
switch will blink.
4. Repeat step 3 until all faults are indicated. After all fault codes have been
displayed, pushing the start button again for 2 - 4 seconds will repeat the fault code
readout sequence.
Source
Showing posts with label fault diagnosis. Show all posts
Showing posts with label fault diagnosis. Show all posts
Friday, May 21, 2010
Wednesday, May 5, 2010
Fuel and exhaust systems - Mono Jetronic fuel injection
The Mono-Jetronic central fuel injection system is fitted to the 1.8 litre (code RP) engine. It is a simplified method of fuel injection (see illustrations). Fuel is injected into the inlet manifold by a single solenoid valve (fuel injector) mounted centrally in the top of the injector unit housing.
The length of time for which the injector remains open determines the quantity of fuel reaching the cylinders for combustion. The electrical signals which determine the fuel injector opening duration are calculated by the Electronic Control Unit (ECU) from information supplied by its network of sensors. Fuel pressure is regulated mechanically.
The signals fed to the ECU include the following:
a) The engine coolant temperature
b) The engine speed and crankshaft position - from the distributor
c) The position of the throttle valve plate - from the throttle position sensor
d) The oxygen content in the exhaust gases - via a sensor (Lambda probe) in the exhaust manifold
Using the information gathered from the various sensors, the ECU sends out signals to control the system actuators as required. The ECU also has a diagnostic function which can be used in conjunction with special VW test equipment for fault diagnosis. With the exception of basic checks to ensure that all relevant wiring and hoses are in good condition and securely connected, fault diagnosis should be entrusted to a VW dealer. Basic testing can be carried out on the system components covered in the following text. More detailed testing can be carried out by using specialised equipment but this must be entrusted to a VW dealer.
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The length of time for which the injector remains open determines the quantity of fuel reaching the cylinders for combustion. The electrical signals which determine the fuel injector opening duration are calculated by the Electronic Control Unit (ECU) from information supplied by its network of sensors. Fuel pressure is regulated mechanically.
The signals fed to the ECU include the following:
a) The engine coolant temperature
b) The engine speed and crankshaft position - from the distributor
c) The position of the throttle valve plate - from the throttle position sensor
d) The oxygen content in the exhaust gases - via a sensor (Lambda probe) in the exhaust manifold
Using the information gathered from the various sensors, the ECU sends out signals to control the system actuators as required. The ECU also has a diagnostic function which can be used in conjunction with special VW test equipment for fault diagnosis. With the exception of basic checks to ensure that all relevant wiring and hoses are in good condition and securely connected, fault diagnosis should be entrusted to a VW dealer. Basic testing can be carried out on the system components covered in the following text. More detailed testing can be carried out by using specialised equipment but this must be entrusted to a VW dealer.
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