I need help finding out if I need a new Control Unit or ecu on a 90 loyale

[Step-a-toe]

Just trying to think about factory radio wiring of this era

Speaking generally not Subie specific, there have been two methods since the days of digital functions such as memory and clock are concerned. Prior to this, car radio just had its power from accessory circuit, so worked on ACC and IGN positions of IGN switch

Once radios had clock and digital memory they got two power feeds. For main functions, the fattest power wire came from ACC, then a skinny wire from direct , constant battery hopefully fused from battery, just for time and memory.

Then someone changed things just to trick me -

They decided the constant battery supply would be main power supply so the fattest power wire would have power while ever battery is connected, and the skinny wire at radio would just be like a relay switch wire for ACC and IGN key positions.

Did the 1990 model use earlier or later method?

I suspect the earlier, skinny constant feed for memory was used until CD players hit cars a few years later.

I got tricked wiring up the newer model with older method, so whenever I cranked the volume I blew a fuse as main power was sucking from my skinny ' signal's wire.

So your buddy must have encountered two power supply circuits in his adventure, but neither of these appear to share circuits with starting and running of engine

EXCEPT , possibly the fusible links near the coolant reservoir on EA82 models......usually fabric covered fuse wire, in red, green, black, in a little plastic box in line of 12 v positive lead from battery

 

Has all this been checked??

 

[rickyhils]

On 6/30/2020 at 11:52 PM, Step-a-toe said:

It might help again if you can identify the wiring your gifted friend shorted out. Where it is located, more importantly the colours, main and trace

Someone may recognise it.

Liked "gifted friend".

[rickyhils]

17 hours ago, Step-a-toe said:

Just trying to think about factory radio wiring of this era

Speaking generally not Subie specific, there have been two methods since the days of digital functions such as memory and clock are concerned. Prior to this, car radio just had its power from accessory circuit, so worked on ACC and IGN positions of IGN switch

Once radios had clock and digital memory they got two power feeds. For main functions, the fattest power wire came from ACC, then a skinny wire from direct , constant battery hopefully fused from battery, just for time and memory.

Then someone changed things just to trick me -

They decided the constant battery supply would be main power supply so the fattest power wire would have power while ever battery is connected, and the skinny wire at radio would just be like a relay switch wire for ACC and IGN key positions.

Did the 1990 model use earlier or later method?

I suspect the earlier, skinny constant feed for memory was used until CD players hit cars a few years later.

I got tricked wiring up the newer model with older method, so whenever I cranked the volume I blew a fuse as main power was sucking from my skinny ' signal's wire.

So your buddy must have encountered two power supply circuits in his adventure, but neither of these appear to share circuits with starting and running of engine

EXCEPT , possibly the fusible links near the coolant reservoir on EA82 models......usually fabric covered fuse wire, in red, green, black, in a little plastic box in line of 12 v positive lead from battery

 

Has all this been checked??

 

As a test, I just went over to my 1991 Loyale wagon (SPFI- FWD) . When the front [closest to battery] GREEN fusible link is unplugged, the ECU does not operate at all. FWIW, the radio still works as do the headlights and everything else. It even cranks over. A peculiar behavior is that [when that 1st GREEN link is unplugged] the IAC makes a chattering sound that then goes away when GREEN link re-connected.  

Anyway, for the 1991 model Loyale, that 1st GREEN fusible link transfers the power to the ECU.

Edited July 2, 2020 by rickyhils
added "cranks over"