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date: Tue, 12 May 2009 04:13:24 GMT,    group: uk.rec.cars.vw.watercooled        back       
MK2 Jetta: Digifant II ECU no power at pin 1   
Hello,

I have a 92 Jetta (1.8 Gas 8v Digifant 2) that has died on me. Brief 
history...this used to be an automatic but 2 years ago I switched it over to 
a 5 spd manual.

Symptoms...will turn over and gets spark but no power to the fuel pump nor 
injectors. I have tested everything...the fuel pump is good (bridged 
terminals at both the fuel pump relay and at the digifant 2 ECU connector, 
and even replaced the FP relay. I tested every connection at the Digifant 
ECU and Ignition Control unit and they are all OK. I tested the hall sender 
in the distributor, the coil, all switched voltages are present at the digi 
ecu connector and ignition control unit and all pins have continuity etc.

Except,  testing pins 1 and 13 of the ECU while actuating the starter does 
not give me any voltage. There is continuity between pin 13 and the 
starter\Ground, and I traced pin 1 back to the fuse panel where it enters a 
relay stamped with 92 (part number 191 927 181). This relay is only found in 
the automatics and serves as a safety to prevent the car from starting 
unless it is in neutral\park etc...

I had a battle with this relay about a year ago when my Jetta died then. I 
can't remeber all the details but I don't think it would turn over then and 
I traced it back to this relay. I thought I was pretty clever and bypassed 
it and fed the switched 12V from the ignition switch (50) directly to the 
relays output going to the starter, but I spiced it in so the relay would 
still get power to the "other" connections that may be switched at the same 
time (if the relay was working).

So...that worked like a charm for over a year. Now the car is dead. After 
doing some more snooping I found this page:

http://www.the152.com/modules.php?name=Forums&file=viewtopic&t=1920

Seems to be exactly what I did....yeah for me. However...apparently this 
relay is also tied to the Digifant II ECU and hence my pin 1 of the ECU 
connector tracing back to this relay (I think it also controls part of the 
Digifant control unit (#3) relay or also called the power supply relay(?). I 
am quite certain the power supply relay is good if I get voltage to pin 14 
at the ECU connector (switched)

So, dare I test fate again....would I be safe to tap this wire from the ECU 
pin 1 (cut at relay stamped 92)  and tap it directly to the switched 50 
coming from the ignition switch and feeding the starter? I have a Haynes 
repair guide book at I found a diagram that shows the circuit with both the 
manual trans and the auto and it is wired this way for the manual. I am 
affraid to send a full current 12V to the ECU as the relay may have a few 
attenuating components like resistors etc...but at the same time I don't 
want to buy a new relay....relay vs ecu....any ideas???

Any guides on cutting this damn relay out altogether for those who have done 
a tranny swap?

Jerry Lynds
date: Tue, 12 May 2009 04:13:24 GMT   author:   Jerry

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