Thanks Santa (the neverending trials of the 400,000klm, 400kw, RB30, manual swapped Stagea)

[niZmO_Man]

ok... so I read "B-52" can someone photoshop 4x turbofan engines onto a Stagea please?

[Duncan]

So, as it turns out, a new wire was the answer I went for, but getting there was not straightforward...

Firstly, I'd been told before by shops that had worked on the car that it had some weird factory wiring, and I can now confirm that is true in at least a couple of places.

For example....that very purple/white wire that provides IGN power to ECU pin 31.....I traced it out of the ECU loom into a connector high on the nav's A pillar under the dash, where it headed up and out of site across the dash, then back down at driver's A pillar. After trying about 8 different relays I found it coming into the back of the fuse box, and confirmed it was the same wire with a multimeter* (more to follow on that....

So, which fuse is the ECU IGN power connected to in my car? 

Very top right, labelled IGN (good), 10A (good), Auto Trans Control (WTF?). It's not impossible it has been f**ked with before, but if so someone removed the pins from the back of the fuse box and moved it somewhere else, noting an AT control fuse would be functionally useless as the car was auto converted to manual long ago. It is not simply a wire cut and joined to the wrong place, both ends of the wire are the same colour just one is in the wrong location (you can see there is an IGN Engine Control fuse in the bottom row 4th from the right.

Note, that is the fuse box sticker from my actual car, so either I have the wrong coin holder sticker, someone f**ked with it post factory, or factory sticker does not match the wiring.....whichever option it is just plain weird.

Undermining the likelihood of someone having gone to that trouble to move a power feed when everything else in the loom had already been butchered....the fuse next to it IGN 7.5a ABS doesn't even have a wire running to it....so no idea where that fuse is on this car.

All strange. But not the problem with my ECU power.

[Duncan]

Now I'd said earlier I'd checked the fuses, and per @Stick180's suggestion I checked them all again. The check was to use the multimeter in continuity mode on the top of each fuse where the little metal tabs are available for that purpose.

All good....except that very "A/T Control" fuse was actually blown when I pulled it out and looked at it. Put it back in, tested it again, there is continuity to both sides even though the fuse is blown. I'll need someone smarter than me, but my suspicion is that I was getting a circuit through a power supply, through an incandescent globe somewhere, to earth, to the shorted wire and back to the other side of the fuse, making it look like the fuse was OK when it wasn't....please anyone that understands this f**kery explain it to me.

Bottom line....that suspicious purple/white wire, in an undamaged factory loom, that goes to the the wrong place in the fuse box has a dead short to earth, confirmed from both ends.  How a single wire in a factory loom can be shorted, especially the best protected loom in the whole car (underneath the top of the dash) is going to keep me awake at night because surely whatever caused the damage has (or will) damaged other wires in that loom too.

So, to finish this long and sad story....cut the purple/white wire where it exits the fuse box, ran a new wire from there to the ECU loom pin 31, fired it up and drove happily into the sunset. Only 4 days of head scratching and peering into footwells to get me there.

Another collection of wire removed (in addition to the earlier photo) and a bunch of 10a fuses that gave their lives for the trouble shooting....thank you for their service. 

And, since the car was in the shed I resealed the cam cover (first time I've ever had a new seal leak on an RB, but the Stagea is that kind of lucky), and I put in the boost doc cam splash plates to try and turn down the blow by a bit while I was there.

Which, was all good because it also let me find the slow coolant leak, turns out it was from the turbo water supply which I nipped up again (the banjo bolt got new washers, and I tightened the hose end and hose to banjo fitting while I was there)

[Stick180]

Well, what a journey that was..

[Dose Pipe Sutututu]

Might as well wrap the dump 

[GTSBoy]

11 minutes ago, Dose Pipe Sutututu said:

Might as well wrap the dump 

You don't think he should leave it to torch the heat hoses?

[Duncan]

nah the heater hoses are fine, I just use the dump pipe as a booster until the coolant warms up

[MBS206]

@Duncan a meter will read continuity, so long as resistance is below a certain threshold.

 

For example, on a headlight globe, you'll probably manage to get your MM to beep for continuity.

 

I always go with measuring resistance.

 

I've had some digital Multimeters beep continuity even with a 100ohm load.

 

Now as for that wire that should be undamaged earthing out... I really really don't want to say it, as I hope it's not the case... Do you happen to have any evidence of mice/rats around?