[urq] 3B swap or 200 20VT - relay j49 - necessary?

[Martin Pajak]

ALex,

Did you have a look at this:
http://www.s2central.net/images/3B_ECU_Schematic.jpg
Looks like the relay is not really needed.  But yes, there are plain
normally closed relays with two output legs.. I have couple in my relay
bin..

However, ECU 27 should be fed by pin B15 on the fusebox.
fuse 26 (your 29) for O2 sensor is fed by pin O on the fusebox
Fuse 28 and 24 are fed by pin 87a on the fusebox.

So you don't really need J49.

I have a question.. how is the actual harness you have from the 200?
Does it have those wires going into the auxiliary relay block?

Cheers


-- 
Martin Pajak

http://www.quattro.ca

1982 Audi Ur-quattro (50,000 mi) new project
1983 Audi Ur-quattro (85,000 mi) Concourse d'Elegance
1985 Audi Ur-quattro (212,000 km) Euro spec. import mit 3B :)
1987 Audi 4000s quattro (205,000 km) wintervagen mit 7A :)


> alexander stickler
> OK. More information for all who answered my earlier
> post:
>
> J49 Electronic Engine Control Power Supply Relay is
> shown on current tracks 17 to 20 on the 1991 200
> Quattro 20V Turbo wiring diagram. It is shown as being
> in position 1 on the auxiliary Relay panel (middle
> row, left side) on the 200.
>
> The relay has 5 pins: Pin 1 comes from fusebox
> terminal BS (fuel pump relay post 47/T), Pin 2 comes
> from L30 (battery), pin 4 goes to (black) goes to pin
> 27 on the ECU, pin 8 goes to fuse 29 and feeds the 02
> sensor heater, and pin 5 to fuse 24, which goes to
> ISV, wastegate freq. valve, and the carbon canister
> frequency valve.
>
> From what I can see, the 02 heater gets voltage from
> post 52/87 of the Fuel Pump Relay and fuse 24 is
> already getting voltage from the same post in the fuel
> pump relay via a hard connection in the fuse box. Pin
> 27 of the ECU appears to be the on/off switch to
> determine whether or not the relay is open or closed.
>
> Is this just a means of managing current by adding
> more wires into the path when the demand from the O2
> heater, ISV, wastegate freq. valve, and carbon
> canister frequency valve is high?
>
> This looks like a pretty basic relay.
>
> Is there a standard relay with 2 output legs?
>
>
> Presently, I suspect I am making a mountain out of a
> molehill on this, but now I am just curious as to what
> this is for.
>
>
> Cheers,
>
> Alex
> --- Martin Pajak <martin at quattro.ca> wrote:
>
>> Alex,
>>
>> Never seen J49 in wiring diagram on the S2... what
>> ECU pins are actually
>> connected to J49?  Can you see what it does
>> (inputs/outputs).
>> Following might help.. no J49...
>>
>> http://www.s2central.net/motronic_pinout_3B.html
>> http://www.s2central.net/images/wee_3B_overview.GIF
>>
>> Let me know
>> Cheers
>>
>> --
>> Martin Pajak
>>
>> http://www.quattro.ca
>>
>> 1982 Audi Ur-quattro (50,000 mi) new project
>> 1983 Audi Ur-quattro (85,000 mi) Concourse
>> d'Elegance
>> 1985 Audi Ur-quattro (212,000 km) Euro spec. import
>> mit 3B :)
>> 1987 Audi 4000s quattro (205,000 km) wintervagen mit
>> 7A :)
>>
>>
>>
>>
>> > alexander stickler
>> > I am just about to fire up my UrQ after the 3B
>> swap
>> > (finally - I said that 2 months ago).
>> >
>> > Questions:
>> >
>> > 1991 200 TQ wiring diagram lists an ECU power
>> supply
>> > relay, 'J49.'  It seems to be fairly rare and the
>> > dealer wasn't quite sure what part it actually was
>> -
>> > what he pulled up was $700.00! With the wiring
>> > diagram, there is a note that says it was not
>> > installed on all vehicles.
>> >
>> > 1. Does this mean that I can drive around merrily
>> > without it?
>> > 2. If it wasn't installed on all vehicles, what is
>> its
>> > purpose?
>> > 3. Is the harness the same with and without?
>> >
>> > I drove the car to the shop that pulled the
>> engine,
>> > trans, and harness for me, so I don't know if it
>> was
>> > there or not.
>> >
>> > 4. Part number - anyone have one for this?
>> > 5. Is J49 a unique ID? - I googled 'J49 Audi
>> relay'
>> > and got a hit for Audi A8L's Fuel Pump Relay 2.
>> Would
>> > this be the same part?
>> >
>> >
>> > Any comments would be greatly appreciated.
>> >
>> > Alex Stickler
>> >
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