S4 AAN into Type 85CQ engine loom wiring

[spink]

What signal does the analogue dash expect? and what is the Motronic ECU output?

dash expects 12v on a type 85 but the output is only 5v

[spink]

Also need my rpm working on the analogue dash, spink did u ever get a chance 2 look in2 making up something

sorry ive only just seen this,no i havnt got around to doing it as yet(like most other things with the car) but it is very simple.I have a drawing i did somewhere,it is literally pennys in parts

it appears 034 dont sell them anymore by the way,certainly doesnt show in their search anymore

[ralleyquattro]

You need a voltage divider,i know 034 sell them for about £60 but I reckon one could be made for peanuts.If you are not in a rush I can make you one at some point when i make one for mine.

That 034 box thing does not work, BTDT.
What does work is hooking up Motronic rpm signal direct to the tacho and then splicing in a 2Kohm resistor straight to the ground, BTDT.

Hope this helps.

[spink]

That 034 box thing does not work, BTDT.
What does work is hooking up Motronic rpm signal direct to the tacho and then splicing in a 2Kohm resistor straight to the ground, BTDT.

Hope this helps.

lovely,should be a doddle then

[S2central.net]

Been looking at this for someone else... anybody else got evidence that the AAN rpm output will drive analog tacho from circa 1986 KV engined CQ ?

I don't understand the above post claiming that a 2kohm 'pull down' resistor is going to help. I am hoping that the tacho gauge is looking for good clean pulse edges and that a nominal 5V or 12V level is not important. I could cook up a little amplifier if it really is required... will find out myself soon enough if nobody else has more experience to share here.

[a4kquattro]

something I ran across today in the shop that I figured I'd add to the archives. We were setting up an AAN harness into a 90 quattro and had no start after wiring all the necessary circuits (black wire for the coils to 12v, blue wires for the injectors to 12v and red wire to constant battery 12v). we were able to communicate with the ecu as well as see rpm in vagcom, but no start (no injector or coil pulse). It turns out, if you 'force' 12v to the fuel injectors instead of routing it through the fuel pump relay like you are supposed to, the ecu will not pulse injectors or coils. moving the blue wires over to the 87a terminal on the fuse box along with the requisite fpr trigger and suddenly pulsing of injectors and coils started.

so again to be clear, if the ecu shows 12v on the injector reference line when its not supposed to (with key on but not while cranking as it triggers the fpr) the ecu will not start pulsing injectors.

[quattro-nick]

the AAN rpm signal works well on a digi dash,no special things required

[Spidey]

the AAN rpm signal works well on a digi dash,no special things required

[tartanmotorsport]

Also if you want to keep your check engine light out you can use my method below to keep the ecm happy.

http://www.motorgeek.com/viewtopic.php?f=6&t=12422&sid=47cd4276372818ba71ded30dc39fc6b3&start=175

Cheers,

Craig