Volkswagen Automobiles Forum banner
1 - 6 of 6 Posts

·
Skoda - Simply Clever
Joined
·
1,239 Posts
Anyone know if this would work?

Taken from ClubGti.co.uk....

Reading Digifant Fault Codes

You can go to your local VW dealer to have the ECU interrogated for faults but of course they will charge you for the privilege and it may not be convenient. This article describes how you can extract the fault codes yourself. I must however start with a few warnings :-

The ECU is a sensitive piece of electronic equipment. The procedure therefore needs to be carried out with care. Any clumsiness could cause major and expensive damage to the ECU.

Make sure you have a good engine earth. The resistance between the battery negative terminal and the engine block should be very low. A poor engine earth will cause all sorts of weird symptoms.

The engine needs to be in good mechanical condition and any misfires should be eliminated.

Being able to read fault codes will not solve all your problems. It is not uncommon to have a sensor that doesn't work properly but which has an output within specification. Such a situation will not result in a fault code. The coolant temperature sensor is one where this can and does happen.

The information given in this article is given in good faith and is correct to the best of my knowledge and belief. However you make use of it at your own risk.

Before going any further have a look in the passenger footwell of your car for two 2-pin connectors. They are usually tucked up under the parcel shelf. One connector, usually coloured black, should have a red wire (supply voltage) and a brown wire (earth). The other connector, usually coloured brown, should have a yellow/white wire (diagnostic connector). If these connectors and wires are not present do not proceed

If the connectors and wires are present then it is worth building yourself a fault code reader.

Fault Code Reader

This is a simple device involving a few pieces of wire, a switch, an LED and some odds and ends. Please make sure you build it properly, though - the idea of loose wires and dodgy connections when interrogating the ECU is not a happy thought. The wiring diagram for the reader is shown below



For making the connections to the footwell sockets I use half a small split pin soldered to the end of each wire and insulated with a piece of heatshrink tubing. To avoid problems build the whole thing into a small box. The best source I have found for the components is Maplins (www.maplin.co.uk). Here is a list of the components used, with the Maplin part numbers :-

Part Maplin Stock No
Red\ LED 5mm WL84F
Non-locking\ push switch FH91Y
Small\ narrow box FT31J
Heatshrink\ sleeving 4.8mm BF89W
Wire Anything you have
Splitpins Approx 2.5mm diameter

Using the Fault Code Reader

Make sure the engine is thoroughly warm - this means taking the car for at least a 10 minute drive.

With the engine stopped connect the fault code reader to the appropriate wires in the footwell connectors and start the engine.

This next bit is far more complicated to describe than it is to do! Close the switch and the LED will light. Hold the switch closed for at least 5 seconds and then release it. The LED will go out and will then flash to indicate a four-digit code. For example code 2324 would be output as 2 flashes, followed by a gap, 3 flashes, followed by a gap, 2 flashes, followed by a gap and 4 flashes.

If you get code 4444 this means there are no faults present. Stop the engine and disconnect the fault code reader.

If you get any other code make a note of it, close the switch for a further 5 seconds and record the second fault code. Continuing doing this until you have read all the codes - this point is signalled by the LED flashing on and off regularly at 2.5 second intervals.

Clearing Fault Codes

Having obtained the fault codes stop the engine and remove the fault code reader. Use a wire to connect the diagnostic connector to earth. Switch the ignition on and after 5 seconds remove the jumper wire. This will clear all fault codes except 2341 or 2343. To clear these you have to remove the multiplug from the ECU for at least 30 seconds.

Fault Codes

This is a generic set of fault codes for Digifant and will include some which are not applicable to your car - so don't go wondering where injector number 5 is for example.

Code Meaning
1111 Internal ECU failure
1231 Vehicle speed sensor
1232 Throttle valve positioner
2112 Craknkshaft position sensor
2113 Hall effect sensor (distributor)
2114 Distributor
2121 Idle switch or throttle potentiometer
2122 No engine speed signal
2123 Full throttle switch
2141 Knock control 1 (ECU)
2142 Knock sensor or circuit
2143 Knock control 2 (ECU)
2144 Knock sensor or circuit
2212 Throttle potentiometer or circuit
2214 Max engine speed exceeded
2221 Airflow sensor/MAP sensor
2222 MAP sensor
2223 Barometric pressure sensor
2224 Max boost pressure exceeded
2231 Idle control
2232 Airflow sensor
2233 Airflow sensor
2234 Supply voltage incorrect
2242 CO potentiometer or circuit
2312 Coolant temperature sensor or circuit
2314 Engine/gearbox electrical connection
2322 Air temperature sensor or circuit
2323 Airflow sensor
2324 Airflow sensor
2341 Lambda sensor or circuit
2342 Lambda sensor or circuit
2343 Mixture control limit - weak
2344 Mixture control limit - rich
2413 Mixture control
4332 Internal ECU fault
4343 Evaporative canister purge valve
4411 Injector no. 1
4412 Injector no. 2
4413 Injector no. 3
4414 Injector no. 4
4421 Injector no. 5
4431 Idle speed control valve
4442 Boost pressure limiting solenoid valve
4444 No faults present
not sure if this is any use or if its been done be for

Edit: forgot the picture!
 

·
Registered
Joined
·
551 Posts
I think Geo was going to try to do this on his 8v when it was having problems, but he found that his car didn't have the plug that you need under the dash I think
 

·
Skoda - Simply Clever
Joined
·
1,239 Posts
Discussion Starter · #4 ·
QUOTE (Geo @ Mar 16 2006, 11:02 AM) <{POST_SNAPBACK}>Yeah I couldn't find the plug, don't think my car had it.

Are you having problems with your car?

No, well other than my MFA reading 99.9 for the MPG
.

But just came across this and thought it was interesting.

Ah ok just found this on another site:

"Digifant II -- Found on later 1987 Golfs and Jettas. Found on all Canadian and US (except California) Golfs and Jettas from 1988 to 1992. The Digifant II computer does not use adaptive control and does not store fault codes. "

http://www.members.tripod.com/~fuelie/whatis.htm
 

·
Registered
Joined
·
888 Posts
Lads,
Connect up as in that circuit and you will blow the LED to kingdom come.

You need a resistor in SERIES with the LED, to limit the current through the LED. Something in the order of 1k ohm should do. (It depends on the current rating of the LED. 1k ohm will allow about 12mA through the LED)
 

·
Registered
Joined
·
551 Posts
QUOTE (PGTi @ Mar 16 2006, 11:45 AM) <{POST_SNAPBACK}>Lads,
Connect up as in that circuit and you will blow the LED to kingdom come.

You need a resistor in SERIES with the LED, to limit the current through the LED. Something in the order of 1k ohm should do. (It depends on the current rating of the LED. 1k ohm will allow about 12mA through the LED)

Yeah I built one of these for Geo (before he found that his car didn't have the plug needed) and incorporated a 1k resistor, as PGTi says, it has to be there or else you will get that lovely electronic "fizzle" and a dead LED
 
1 - 6 of 6 Posts
Top