Project Phoenix: Power and Wiring

[chazsandiego]

Hello all! Awhile back I posted about my gf's 535i that caught fire due to an electrical fire (headlights). After successfully rolling the windows back up with an external battery (thanks again) the next step is to get some power back to the dash.

I've been waiting for another m30b35 to arrive at the junkyard and recently a pair of 735, e32's have shown up. I'm hoping to cut out part of the wiring harness as shown in the picture and replace it with one from the salvaged 7er.



I'm not sure how well this will go, so if anyone has any protips or moral support they would be greatly appreciated!

[CarterH]

Headlights did this? That's very unusual. I have to wonder about differences in wiring though since I'm sure the E32 is probably a little different to the E34 since it had slightly different features.

Still, for something like this there's no harm in trying. Those wires need to come out anyway so if this doesn't work, you can just wait for an E34 to show up and get the wires then.

[moroza]

I hope that's not your first bite of electrical work, because it's a lot to chew. You have wiring diagrams, a good soldering setup, and considerable patience for not only doing the actual splice work, but troubleshooting any gremlins that remain?

I'll stay tuned and offer moral support. When I did wiring jobs this scale, I made a spreadsheet, one per bundle (so two, in your case):

	Actual wire in patient	Wire in diagrams, if different	Actual wire in donor	Wire in diagrams, if different	Where it goes	Notes
1	1.5 RD		1.5 RD		Flux capacitor power
2	1.5 BR/BK		1.5 BR/BU		Flux capacitor ground
3	0.35 GN/GR	0.35 GN	0.35 GN/GR		Flush control module doomsday signal
4	0.75 BK/WT		0.75 BK/WT		Gremlin generator	Disable this feature anyway.
5			1.0 YL/PU/WT		Secret hyperjet switch	Donor had hyperjets, patient doesn't; disable.

Another suggestion is consider this car's future and evaluate the importance of retaining features you don't use or have. I deleted my data link wires when they melted down. Less wiring = fewer fire hazards and other problems.

[south42]

I have the complete engine compartment harness for a 535i. Parting a 91 535i.


Pm me if interested.



Andy

[chazsandiego]

I've made some decent progress on getting the harness prepared. Was curious though how I can determine which wire is which in these diagrams.

I can figure out the wiring on the ABS side but I'm not sure what is happening on the fuse block side. My guess is a visual inspection will be the only way to determine what is what. But I'm hoping someone will have another idea.

Thanks!

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[moroza]

Recommend you use the factory wiring diagrams, for they list wire gauge in addition to color, helping disambiguation. They also list splice locations. Both features would help figure out which red wire goes where. In this case, they're electrically equivalent, only a gauge difference would matter.

[fo3]

Isn't red 'always hot' straight off the battery/"distribution box"?

[chazsandiego]

Recommend you use the factory wiring diagrams, for they list wire gauge in addition to color, helping disambiguation. They also list splice locations. Both features would help figure out which red wire goes where. In this case, they're electrically equivalent, only a gauge difference would matter.

Thanks moroza! I also have the electrical troubleshooting manual so I will reference the wire gauges. I'm just using this "quick sheet" that I found on prodemand to begin the sorting process.

Oh and thanks for the link! I'd been struggling to remember where I downloaded the manual originally. Kept thinking it was "armchair qb" oh well

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[chazsandiego]

Isn't red 'always hot' straight off the battery/"distribution box"?

That's what I was thinking too, but since this is for wiring the ABS I'd rather not take any chances.

Im sure there will be a few of those down the line with less essential accessories

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[chazsandiego]

Update:

I told my automotive electrical teacher about my plan to splice an e32 wiring harness onto an e34 and he thought it was one of the worst ideas imaginable. He said it was something a "meatball" would do.

Anyways as luck would have it a comparable e34 535i arrived at the junkyard around this time and I was able to salvage a complete engine harness without cutting anything.

I don't know why I thought that the harness would be "hard wired" to the vehicle and necessitate being cut out. It doesn't, and everything just unclips under the drivers side kick panel. I had no idea!

Hoping to have time this weekend to get all the new wiring in and see some signs of life on the dash!



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