Harness Power/Ground Wiring Confirmation ('89 E30/'95 S50)

[PutterMcGavin]

Ok before I go blowing stuff up I’d like some feedback to ensure I have everything hooked up correctly. First a couple “basics”…

Chassis: ’89 325is (originally auto, swapping to G260 manual)
Engine: S50 - ’95 M3 (9/’95 build)
Harness: S50 - ’95 M3 (9/’95 build) AUTO harness
Tranny: G260
Flywheel: Lightened single mass G260
Starter: G260 (duh…)

So I did all wiring (fingers crossed) and was left with the following:

Passenger Side:

- A – RED/Delete(?)/Goes to E36 harness/SPLITS into two red wires on driver’s side near fuse box– Thought to be E36 fusebox power and starter wire. Will delete as I’m using the E30 starter wire and retaining E30 fusebox power lines.
- B – RED/Power Block(?)/Goes into E36 harness/Unsure of termination point
- C – BROWN/Strut tower ground/Goes into E36 harness/Terminates with other brown grounds
- D – UNKNOWN/From Power distribution block/Goes straight to large post on starter



Alternator (not shown)
- D – UNKNOWN/From Power distribution block/Goes straight to large post on starter
- E – (NOT SHOWN) RED/Goes from large post on Starter (stacked with D) to the alternator large post
- F (NOT SHOWN) UNKNOWN color/Goes from small post on alternator to the harness – think this is the signal wire to the alternator?

Driver Side:

- G – RED/Starts at A above/ Would usually go to fusebox for power on E36’s. Will be deleted for the swap in favor of E30 wiring?
- H – RED/Starts at A above/Would usually go to the large post on the starer in E36’s. Will be deleted for the swap in favor of E30 wiring?

[Blaine0002]

Oh god... what???


Why dont you use the power lines on the harness?? Just power the fusebox with the new lines... definately the easiest way to do it!

[PutterMcGavin]

Oh god... what???


Why dont you use the power lines on the harness?? Just power the fusebox with the new lines... definately the easiest way to do it!

Hmmmm I heard of both but since using the E30 lines only required a single hook up rather than figuring out the E36 lines I went with that.

Can anyone else weigh in? Really don't want to fry this car! Ha

[PutterMcGavin]

Bump anyone else a wiring guru?

[BenjaminButtton]

You have it mostly correct I believe.

Delete the stuff that you know for sure powered the e36 fusebox, you have all that correct I believe. I removed that and retained the e30 starter power wire, and fuse box power wiring was never touched (just left it alone).

I'm a little confused on all your starter wire numbers etc, but you should be able to figure it out.
Remove the e36 only fusebox wires, use the stock e30 setup for that (unless you removed the fuse box to respray or something you probably didn't remove that).
Use the e30 starter power wire (or e36, doesn't really matter just have a heavy wire from the power distrib to the starter main lug).

Brown is ground, Red is power. You have 'B' and 'C' correct. Good luck!

[dsobering47]

Pro-tip: Use any multimeter (a $5 Harbor Freight one is fine) set to continuity and verify all power/ground connections. Its easier to visualize AND have the multimeter telling you where the wires go. Learn the crap out of your harness....it will help in diagnosing anything later on.

[Blaine0002]

I think my harness must have been different being an 87! Everything was on my engine harness not to my fusebox.

[PutterMcGavin]

You have it mostly correct I believe.

Delete the stuff that you know for sure powered the e36 fusebox, you have all that correct I believe. I removed that and retained the e30 starter power wire, and fuse box power wiring was never touched (just left it alone).

I'm a little confused on all your starter wire numbers etc, but you should be able to figure it out.
Remove the e36 only fusebox wires, use the stock e30 setup for that (unless you removed the fuse box to respray or something you probably didn't remove that).
Use the e30 starter power wire (or e36, doesn't really matter just have a heavy wire from the power distrib to the starter main lug).

Brown is ground, Red is power. You have 'B' and 'C' correct. Good luck!

Got it thanks! I tried starting it and the starter engages correctly but she won't turn over. Checking all of the grounds, etc. now.

Pro-tip: Use any multimeter (a $5 Harbor Freight one is fine) set to continuity and verify all power/ground connections. Its easier to visualize AND have the multimeter telling you where the wires go. Learn the crap out of your harness....it will help in diagnosing anything later on.

Yep I have one and have been using it for continuity, etc. I was simply wanting to make sure the leads were hooked up correctly. Now I need to figure out why she won't turn over...

I think my harness must have been different being an 87! Everything was on my engine harness not to my fusebox.

Hmmmm I could have used the harness but am just using the E30 stuff instead. VERY easy!

[PutterMcGavin]

FYI this should be correct.

I tried starting it and had spark but no fuel. Pulled the pump and there was about 12 gallons of 10 yo gas and rust in the tank. Needless to say new tank and pump ordered.

I sprayed some starting fluid into the manifold and it started and idled immediately before quickly dying. So it should be good once I get fuel back...