S4 Spider Radio Harness

[Cintos]

Greetings: I had searched the forums for help securing a wiring harness to adapt a newer head unit to the original factory supplied connection plugs. Finding only a possible reference to a Toyota-fitment kit which did't seem to fit, I stumbled onto a kit from Crutchfield which works perfectly. Their unit #70-1381 is identified as fitting the 1985 through 1989 Alfas, but it mates with my 1991 S4 connectors fine.

The unit I bought - a Sony - does not have an input to control the unit's lighting level, so the only missing wire in the Crutchfield harness (Black-White on pin 4 of 6-pin). If your unit has such an input, the smaller 6-connector plug would need to be enhanced.

I was unaware, but it seems that the industry has settled on a common color code for LF, RF, LR, RR and the power/antenna remote wires. Makes getting everything joined a bit less stressful. Splicing up the Crutchfield harness with the Sony's harness simply matching colors resulted in a correctly wired installation.

One additional note on the Alfa- supplied wiring diagrams. The radio connectors are displayed as two connectors, but as a single row, vs the actual double-row plugs. As implemented, the six-connector plug runs 1,2,3 on the bottom and 4,5,6 above them viewed with the lock indentation on the bottom. Similarly, the 8-connector plug runs 1,2,3,4 on bottom and 5,6,7,8 above.

[Tifosi]

Now there's some useful info for future reference. :thumbsup:

[Cintos]

..... I should have known it wouldn't be that easy.

After getting the Crutchfield harness wired up and the radio functioning - and after posting the above - I set about balancing the 4 speakers and found that the rear left and right were swapped. The harness expects the factory connector to march RF, LF, RR, LR - ya'd think. But Milano wants to exert its logic, which is RF, LF, LR, RR. positive on the 8-pin connector pins 1,2,3,4 and negative on pins 5,6,7,8 respectively.

<<So to make the harness work correctly, the rear two pairs of wires need to be swapped>> That can be done when the harness is spliced to the radio wires, or by swapping the pins at the connector.

Just to make things more complicated, I read the positive & negative above by verifying that pin 1 on the speaker jack is connects to the negative (small) pin on the speaker, and pin 2 connects to the positive speaker pin. Crutchfield's supplied diagram is reversed, which makes all the wire color wrong, but as long as they are all switched, makes no matter. (?) All of my speakers had been changed by a PO, so don't read too much into the polarity point.

Unfortunately, Alfa's schematic diagram on shop manual p40-15 does not denote speaker polarity. It does, however, contain a documentation error. It shows that the at the right front speaker, a grey wire is on terminal one and a grey-black is on terminal 2. The opposite is true - which is a good thing since the 1-2-3-4 and 5-6-7-8 march would be broken.

- Cintos