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June 29, 2008 10:35 a.m. GordonD None

I have a 1072 2002 which will be used mainly for track days. Over the last 3 years I have had it soda blasted - rust fixed - and then repainted it myself.

Last year I had the engine rebuilt and overhauled the Weber DCOE 45's myself.

Last big challenge is the wiring harness. It has been hacked into a thousand times and everything is brittle so I would love to have it all redone. Cash is a bit short these days and there are no kits (except generic ones) so i am looking for some advice on how to do this a) without too many tears and b) as inexpensively as possible
June 29, 2008 11:02 a.m. iceracer New Reader

First you need a wiring diagram, and lots of patience.
June 29, 2008 11:06 a.m. mel_horn HalfDork

(I think you mean 1972...they've been around awhile but not THAT long!)

My suggestion is to find a local example as either a parts source or as a live wiring diagram. You don't say where you are but if you are close to Central PA I may be able to help.
June 29, 2008 11:14 a.m. GordonD New Reader

mel_horn wrote: (I think you mean 1972...they've been around awhile but not THAT long!)

My suggestion is to find a local example as either a parts source or as a live wiring diagram. You don't say where you are but if you are close to Central PA I may be able to help.

Definitely 1972

I have wiring diagrams and obviously the car still has everything there.

I keep walking up to it and then chickening out. I had thought of pulling the fuse panel then just working on replacing whatever wires lead to each fuse by following them back to whatever they connect to and making a new wire etc.

Just seems a bit daunting and maybe what I need to do is just start
June 29, 2008 6:10 p.m. iceracer New Reader

One thing, since it is a track car, you can eliminate a lot of the wiring. Don't trust crimped connections, solder everything.
June 29, 2008 8:22 p.m. Spitsix New Reader

Painless type wiring system?
June 29, 2008 8:48 p.m. mel_horn HalfDork

Spitsix wrote: Painless type wiring system?

THERE you go...

if it's really going to be a track car that will never see the street again.

NOTE: Saw an ad for what I thought was two cars in the local paper. "2002 325i" I thought" COOL! An 02 and an E30! "; then I realized...

THIS MIGHT HELP: Terminal Designation Numbers (courtesy www.e30tech.com but should apply to 02s as well): 30-Battery hot

31- Battery ground

50- Hot during crank

X- Battery voltage supplied by load reduction relay (interrupted during crank)

15- Hot during crank and ignition ON

85- Relay ground terminal

86-Relay switching voltage terminal

87-Relay output terminal

B+ main battery hot connection at alternator

D+ Alternator warning light and field exitation circuit

You might also try 2002 Forums
June 29, 2008 10:53 p.m. 02Pilot New Reader

There really isn't much to the wiring in these cars, and you can eliminate a lot in a track-only car. Working from the fuse box will probably be the way to go if you're doing it from scratch. Just get some spools of wire and go at it. The OE crimp-on terminals are still available from BMW if you want to use them.

The only place you'll get into a rat's nest of wires is under the dash, and a lot of that can go. You might consider a dedicated switch panel in the center console, rather than dealing with the old OE switches. Get new standard 4-pin relay sockets and relays while you're at it.

Wiring diagrams are in the Haynes manual, though I think the BMW service manual ones are better. These will be harder to source, but may be worth the trouble for a project of this size. I do think that you'll be better off setting up a switch panel and deciding yourself where you want the wires to go. There are very few things on a 2002 that will complicate this.
June 30, 2008 7:56 a.m. Jensenman SuperDork

For a track rat, I'd do the start from scratch thing rather than the Painless. Their stuff is pretty good but if you aren't running turn signals, heater blower etc it doesn't make sense to spend the big $ on it.

Put the fuse block on the dash within easy reach of the driver. That vastly simplifies things if something goes wrong. Then run wires from there.
June 30, 2008 8:55 a.m. pigeon New Reader

I don't know if this would help in this case, but the Mobile Tradition parts catalog is available online using the following instructions that I shamelessly cribbed from another site:

FYI: The BMW Mobile Traditions ETK is available FREE online. This is the same parts system that BMW Dealers use, except it is missing the pricing and linkage to warehouse(s) for parts availability, etc. It is also available on CD ($40) at BMW dealers and several of the popular online parts houses. The ETK covers older BMW models like the 2002, E12 etc.

BMW's site makes it a little tough to provide a direct link to the Online ETK, but if you go to... http://www.bmw.com/generic/com/en/fascination/discover/history/mobiletradition/ind...

Then: * Click on Parts Supply Select Historic Parts catalog (in the popup menu) The click on the little grey "No Online!" below the description of the CD contents...

...you will get to a screen that allows you to Register. Don't get excited yet, the response by email with a Login ID took nearly 24 hrs in my case.

The exploded parts diagram graphics in the online version are the 'same' as the commercial CD BUT much better resolution when you pop them up in the separate (graphics+) window. Even better you can then capture them and build a mini exploded diagram catalog for any rebuild or repair project. All in all, the free Online version is much better than the commercial CD if you have a broadband connection.

Also, www.realoem.com is the complete online catalog of bimmer parts for virtually everything BMW's ever made.

Scott
June 30, 2008 9:22 a.m. Wall-e SuperDork

If your making your own harness I'd look at replacing the fuses with push button circuit breakers somewhere you can reach them from the driver's seat. We usually had a row of switches with the corresponding circuit breaker under it so it was easy to access in case it popped.
June 30, 2008 9:43 a.m. Jack SuperDork

iceracer wrote: One thing, since it is a track car, you can eliminate a lot of the wiring. Don't trust crimped connections, solder everything.

Yes, eliminate much of the wiring, but get a good crimper, don't trust soldering.

There are definitely two camps to the solder versus crimp arguement. There is a reason OEM's crimp, not solder and I don't believe it's all cost. A good crimp anchors the wire, without embrittling the connection. Soldering will leave a defined part where the flex will occur; it's where the solder in the wire stops.

Personally, I don't have an issues with either, IF they are done correctly, but take your time and make a good decision on how best to terminate electrical connections on your vehicle.

Jack
June 30, 2008 11:16 a.m. GordonD New Reader

Thanks everyone - seems like it's courage I lack not information.

I looked at Painless but I do need to drive to and from the track so need signals etc - plus I was thinking of adding some driving lights to augment the stock headlights so need some extra circuits/relays etc

I have looked at the Mobile tradition site too but while it lists the harnesses they are no longer in production