[Es2] [urq] Wiring Harness

Steve Eiche seiche at shadetreesoftware.com
Thu Apr 27 02:25:52 EDT 2006

Yes, the black "B" connector from the S2 harness plugs right in and the 
signals are correct.  That will almost getting you running and is much 
better than the AAN S4/S6 harness and '91 200q harnesses for a many 
reasons, but if you want to use the rest of the wires, like oil 
pressure, oil temp, coolant temperature, fan turn-on with the after run 
pump,   A/C compressor control, etc., there is alot more to connect.  
When you start talking about putting in an AAN harness, you also have to 
connect the speed signal, which is a little tricky on an ur q with an 
analog dash (but can be done) as well as the relays and power 
connections being in the wrong place.  Then under the hood there is the 
issue with the throttle body connector and idle stabilizer connectors 
being in the wrong place if you end up using a different intake .  Yes, 
all of the signals are there and you can match signal up to the car 
side, but you need to know what is and what is not needed.  That is 
where most people have trouble.  On top of that, there are things like 
A/C compressor signals, and fan controls that most people ignore, but I 
consider necessary.   To me, getting it running is one thing, getting it 
working "right" is another.

When I do a wiring conversion, I unwrap the interior side,  remove 
everything that is no longer used, and connect up everything  with 
factory connectors and no splices unless it is absolutely necessary.  
With a 3B '91 200q harness, you need to remove about 30 200q specific  
wires, and then adding back wires for the wipers, windshield washer 
pump, etc. and then add the proper connectors and jumpers to mate up to 
the car.  AAN S4/S6 harnesses are much worse.   FWIW, I have done "plug 
and play" 3B harnesses for three early ur qs, an '84s, '85 and AAN 
harnesses for an '84 and an '87 4kq.  I also modified an RS2 harness for 
an '87 4kq.   Even after doing it a few times and all my notes it still 
takes me ~ 40 hours of honest labor to make a 3B harness truly "plug and 
play" for an ur q, 10+ more for an AAN S4/S6 harness.  An RS2/S2 harness 
makes things easier, but they aren't exactly easy to find in the US .   
For that reason, I won't even do it anymore, as no one would want to pay 
for what I would have to charge to make it worth my time and each time I 
say "never again".  Making $10 bucks an hour isn't worth it.   I have 
also redone an '83 with a 3B harness from a '91 200 that the first 
mechanic billed 100 hours of labor on the electrical system.  It worked, 
but it was a mess.   It took me 10 hours just to clean it up.

No offense Martin, but there is more to the harnesses than just the ECU 


Martin Pajak wrote:

>All of the engine related plug on the S2 harness plug straight into the
>Coupe/4kq fusebox.  Afterall it is the same fusebox as on S2/RS2.
>Only the stuff for the trip computer, tach, temp gauge and cruise control
>speed signal need to be connected into the wiring harness... even then most
>of the car side plugs can be used and made to look factory.
>Here are the notes on the engine wires that need to be plugged into the
>3B ECU Pin Out Signal Description
>1. Output stage for Ignition coil N70 (Green/White)
>2. Coding Plug (Yellow/Black) 
>3. Fuel Pump Relay J17, G6 (Brown/Green) Fuse Box "BS" (Green/purple) 
>4. Idle Stabilizer N71 (Gray/Black)
>5. Carbon Canister Frequency valve N80 (Black) 
>6. Tachometer (Purple) DigiDash "T35/31" (Purple) 7/25 
>7. Mass Air Flow Sensor G70 (Black/Gay)
>8. Hall Sender, G40 (signal wire) (Green)
>9. Open, not used
>10. Ground (Brown/Yellow)
>11. Knock Sensor #1 G61 (Black)
>12. Hall sender, altitude sensor, etc. (+5V) supply (Red/Black)
>13. Diagnostic plug (L wire) (Black/White) Diagnostic "T2a" 
>14. Control Unit ground (Brown/Red)
>15. Injector #3 control signal N32 (Brown/Green)
>16. Injector #2 control signal N31 (Brown/Blue)
>17. Injector #1 control signal N30 (Brown/Black)
>18. Terminal 30 (+12V) supply, Fuse #26 (Red/White) Fuse Box "L30"
>19. Control Unit ground (Brown/Yellow)
>20. Open, not used
>21. Open, not used
>22. Diagnos. out (Gray/Brown) Diagnostic"T2b"DigiDash"T35/33"FuseBox"ILa"   
>23. Wastegate Frequency valve N75 (Green/Yellow)
>24. Control Unit ground (Brown/Red)
>25. Mass Air Flow Sensor (+ pin 4) G70 (Blue/Purple)
>26. Mass Air Flow Sensor (+ pin 2) G70 (White/Green)
>27. Terminal #15 (Ignition +12V) (Black) Fuse Box "B15")
>28. Oxygen Sensor G39 (green coax cable)
>29. Knock Sensor #2 G66 (White)
>30. Ground (Black/Purple)
>31. Boost Pressure Gauge (Purple/White) DigiDash"T35/16"(Brown/white) 2/25 
>32. Trip Computer (Blue/Black) DigiDash "T35/34" (White/Green, Green/White)
>33. Open, not used
>34. Injector #5control signal N83 (Brown/Red)
>35. Injector #4 control signal N33 (Brown/White)
>36. Multifunction temperature sensor F76 Pin R (Blue/Black)
>37. Voltage Supply input (+12V, Fuse #28, Blue/Black) Fuse Box "87a"
>38. Coding plug (Brown/Blue) 
>39. Coding plug (White/Black) 
>40. A/C Compressor (Green/Black)
>41. Idle speed increase signal (A/C on) (Brown/Black)
>42. Open, not used
>43. Open, not used
>44. Intake Air Temperature Sensor G42 (Blue)
>45. Coolant Temperature Sensor G62 (Red/Green)
>46. Altitude Sensor F96 (Gray)
>47. Engine Speed Sensor G28 (Gray)
>48. Ground for reference and speed sending units (shown as two wires, one
>Red, one Blue)
>49. Reference G4 (62 degree before TDC) sending unit (Purple)
>50. Open, not used
>51. Open, not used
>52. Idle Switch F60 (Green/Purple)
>53. Throttle Valve Potentiometer G69 (Gray/Blue)
>54. Coding plug (Red/Yellow) 
>55. Diagnostic plug (K wire) (Yellow/Blue) Diagnostic"T2a"  
>Martin Pajak
>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 :)
>1990 Audi V8 quattro (365,000 km) pipe and slippers
>-----Original Message-----
>From: Jack Walker [mailto:JackW at ihco.com] 
>Sent: Wednesday, April 26, 2006 7:46 PM
>To: seiche at shadetreesoftware.com
>Cc: Martin Pajak; es2 at audifans.com; urq at audifans.com
>Subject: RE: [Es2] [urq] Wiring Harness
>Baby with the bath water, pretty good???
>Wasn't something I had control over, before it was sitting in a scrap
>yard, my original goal was the harness, the fuse box, the dash,
>everything. But when it went to the scrap yard, I didn't have a lot of
>options. They weren't even going to let me in the yard after it got
>loaded into the dump box, until they asked for the title. Told them to
>bring it back...or I would call the police and say it was stolen.
>The major reason I went for the fuse box surround was the lip in the
>under hood area that another fuse box could eventually go on top of
>along with the butyl tape. I've got a fuse box and harness from a FWD
>4000 and a bunch of dash parts...? There are a ton of 4000 CSQs around
>Don't things like the Ur all the dash display-speedo, tach, wiring have
>to be spliced into what ever harness I end up using, On the Lighting,
>A/C, Starter, rear wiper, and the battery can't I use the Ur wiring?
>Jack Walker
>503) 419-4601  Direct Phone Line
>503) 807-3807  Cellular Phone
>-----Original Message-----
>From: Steve Eiche [mailto:seiche at shadetreesoftware.com] 
>Sent: Wednesday, April 26, 2006 5:22 PM
>To: Jack Walker
>Cc: Martin Pajak; es2 at audifans.com; urq at audifans.com
>Subject: Re: [Es2] [urq] Wiring Harness
>Well, you kind of threw away the baby with the bath water.  There is no 
>need replace the area where the newer fusebox mounts.   The area is 
>already properly shaped for the newer fuse box.  All you need to do is 
>cut the hole for the housing and seal it with butyl tape (same stuff 
>used by the factory).  It will be indistinguishable from the later fuse 
>box setup.  You will want to remove the old fusebox bracket, and weld in
>the two brackets for the relay panel, but that is all you need.  You 
>should have saved the wiring and forgotten about the sheetmetal.  You 
>will want CGT wiring for the rear harness(es if you have a rear wiper), 
>as well as the control stalks, but 4kq harnesses will work for the 
>rest.  Either way, you will have to make some changes, especially in the
>lighting circuits, A/C, starter and battery no matter what you do.
>As for the RS2 harness, yes, that will work much better than the S4/S6 
>AAN harness.  I'm not sure where Martin gets his 99% from, but I have an
>RS2 harness, and while the black connector with five wires that goes to 
>the fuse box has them in the right places, and the fuses are easy to 
>connect, but the other 19 are not plug-in compatible.

Steve Eiche
Shade Tree Software, LLC
http://www.shadetreesoftware.com   http://www.prodiag-hd.com
seiche at shadetreesoftware.com

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