Jump to content
  • When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.

Help me diagnose trunk mount battery / wiring issue


kris

Recommended Posts

I am finally ready (after 18 months) to start my car, but I can't get any power to anything. I am an admitted wiring dweeb so hopefully someone can help.

The PO did the rear battery mod, and I did a refurb replacing the E30 battery ground, e30 terminal block and E30 starter cable. At the same time I replaced the front wiring harness with a new one from BMW...so that means I pulled everything from the fuse box etc and rewired. I picked up a new battery today to eliminate that as an issue. So for the starter I now have the E30 hot cable and the hot cable from the NOS harness...are they both supposed to be connected? What about the extra hot cable that would have originally been connected to the battery when it was mounted in the engine bay...do I just tape it off?

I also have not grounded the motor or alternator yet, will ground them to the frame today.

I figure I have a ground issue or the harness is not getting power. Help please wiring experts, I want to drive my car!!

New terminal block, red wire is the hot for my H4 conversion

ot16ol.jpg

Starter cable attached to the terminal block

2hmzm0p.jpg

E30 M3 starter, e30 Starter cable attached, harness hot attached as well, is this correct?

2hrzu6u.jpg

Extra hot cable from original harness...what do I do with it?

15fk4di.jpg

Battery relocation temporary setup - is this ground acceptable??

2cxvwd1.jpg

New wiring

2q0ve51.jpg

70 M2 2.5L 

Link to comment
Share on other sites

1) Looks like you don't have a chassis ground to the block. Make sure you run a big wire (at LEAST 4AWG) from the block to the fender. I recommend the ground point coming off the harness ahead of the relays. That keeps it all in one place.

2) Where is your alternator (+) wire? I'm unfamiliar with tii wiring, but is that the big, fat wire with no connection? If so, run it to the same (+) wire on the starter, or get yourself a distribution block.

3) That ground doesn't look like the most optimal place. I'd try to find thicker metal. I used the rear subframe carrier bolts for my ground.

SIG4.jpg

click signature above for my resto blog

Link to comment
Share on other sites

1) Looks like you don't have a chassis ground to the block. Make sure you run a big wire (at LEAST 4AWG) from the block to the fender. I recommend the ground point coming off the harness ahead of the relays. That keeps it all in one place.

2) Where is your alternator (+) wire? I'm unfamiliar with tii wiring, but is that the big, fat wire with no connection? If so, run it to the same (+) wire on the starter, or get yourself a distribution block.

3) That ground doesn't look like the most optimal place. I'd try to find thicker metal. I used the rear subframe carrier bolts for my ground.

The alternator is wired in with the harness wire and plug - you can kinda see it all here:

2e0mjow.jpg

The extra hot is the main feed for the battery.

70 M2 2.5L 

Link to comment
Share on other sites

If you're not getting ANY power to ANYTHING then it is most likely either an insufficient ground at the battery or something wrong between the battery and the main electrical connection (not starter). First make sure the battery is grounding correctly (test light from battery positive to body. Then start at the e30 terminal in the engine compartment. How about at the fuses: electricity there? Keep going. Wiring is simple and logical and the problem is usually something very simple; just a matter of finding it.

now: '72 Inka 2000 touring, '82 Alpina C1 2.3  & '92 M5T (daily driver)

before: a lot of old BMWs (some nice, some not so much), a few air-cooled 911s and even a water-cooled Cayman S

Alpina restoration blog: https://www.alpinac1.com/

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • BMW Neue Klasse - a birth of a Sports Sedan

    BMW Neue Klasse - a birth of a Sports Sedan

    Unveiling of the Neue Klasse Unveiled in 1961, BMW 1500 sedan was a revolutionary concept at the outset of the '60s. No tail fins or chrome fountains. Instead, what you got was understated and elegant, in a modern sense, exciting to drive as nearly any sports car, and yet still comfortable for four.   The elegant little sedan was an instant sensation. In the 1500, BMW not only found the long-term solution to its dire business straits but, more importantly, created an entirely new
    History of the BMW 2002 and the 02 Series

    History of the BMW 2002 and the 02 Series

    In 1966, BMW was practically unknown in the US unless you were a touring motorcycle enthusiast or had seen an Isetta given away on a quiz show.  BMW’s sales in the US that year were just 1253 cars.  Then BMW 1600-2 came to America’s shores, tripling US sales to 4564 the following year, boosted by favorable articles in the Buff Books. Car and Driver called it “the best $2500 sedan anywhere.”  Road & Track’s road test was equally enthusiastic.  Then, BMW took a cue from American manufacturers,
    The BMW 2002 Production Run

    The BMW 2002 Production Run

    BMW 02 series are like the original Volkswagen Beetles in one way (besides both being German classic cars)—throughout their long production, they all essentially look alike—at least to the uninitiated:  small, boxy, rear-wheel drive, two-door sedan.  Aficionados know better.   Not only were there three other body styles—none, unfortunately, exported to the US—but there were some significant visual and mechanical changes over their eleven-year production run.   I’ve extracted t
  • Upcoming Events

  • Supporting Vendors

×
×
  • Create New...