[urq] relay j49

[Frank de Kat]

At 12:00 PM 29/06/2006 -0400, you wrote:

3. Re: 3B swap or 200 20VT  - relay j49 - necessary?
>       (alexander stickler)
>
>------------------------------
>
>Message: 3
>Date: Thu, 29 Jun 2006 10:40:05 -0400 (EDT)
>From: alexander stickler <a_stickler at yahoo.com>
>Subject: Re: [urq] 3B swap or 200 20VT  - relay j49 - necessary?
>To: Martin Pajak <martin at quattro.ca>
>Cc: urq <urq at audifans.com>
>Message-ID: <20060629144005.31358.qmail at web60718.mail.yahoo.com>
>Content-Type: text/plain; charset=iso-8859-1
>
>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

Hello Alex:

That relay sounds very much  like the MAC 11 5000 turbo fuel pump relay.

I'd say that your pins 27 (Grounded by ECU when on)  and pin 1 are the 
'coil' terminals of the relay,

and pin 2 is high current 12v feed, and pins 8 & 5 are the load (output) .

It's not

" 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?",

as such, but a power feed for those devices  that don't need power until 
the motor is running (i.e., turned on by the ECU). More than likely comes 
on at the same time as the fuel pump.

Effectively, you could use any quality relay with only 1 load output, and 
connect the feeds to 8 & 5 together.

Regards,

=Frank de Kat=