Wiring harness help with pictures

[jbowen944]

Hey All!

Ran into an issue running the harness and wanted to check with you all on it. Which way is it supposed to run/where does it bolt to the engine? I just want to make sure I'm running it the right way to not mess up the cable. the area i'm concerned on is the spot where all the wires sort of split on the harness, i've got iyt near the starter. Also, for the alternator, what order does the bushings, adjusting bar, and toothed bar go in to bolt on?

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[jbowen944]

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[OLD MAN]

Great question!

I have taken out about 5 1.8 post 80 engine now and still wonder about this.

For me the issue is trying to figure out a better way to run some of the wires making it easier to work on the engine. Mainly getting the starter out - I keep my cars for a long time. Which means I have had a couple of E21s I have had to change the starters in more then once each.

I looked and could not find a picture to share.

Your first picture first post is what I did with the harness going across the back of the engine and to the firewall. But this is not where the factor ran it. They ran it up between the #3 and #4 intake runners I believe. This makes it really hard to take the intake off so I ran the wires where you did.

Thinking more the factor may have run that wire group across the top of the intake and down between the #2 and #3 intake runners. Or one of my E21s had been worked on before I got it.

[320iAman]

Mine is run between 3rd and 4th intakes, this is original wiring, its up the person where he wants to run the wiring harness, the cylinder head does not get removed very often and there is only one wire which causes an issue thus a bullet connector or a male/female spade terminal connection takes care of that.

Randy

[jbowen944]

For the alternator, I've got the blue wires hooked up, the red wire screwed on, and its grounded, is that all? And for the battery, theres the black cable coming from the wiring harness, I'm assuming this goes to the negative on the battery? The red comes from the body of the car? What is the red cable coming from the fuse box? On the starter, where do the wires connect? Theres the double red wires, the black wire, and the small yellow wire. My car basically came disconnected, so i don't have any reference images.

[320iAman]

The alternator has 3 outside wires connected to it.s-l1600.jpg The Red B+ wire on the alternator gets connected to the start solenoid on the starter-the big threaded lug and then there is 2nd red wire that goes from the start solenoid to the positive battery post, The D+ is generally a smaller Blue wire that is 12 Volts + and energizes the field coil in the alternator and the alternator light in the instrument cluster, The long screw sticking out has a wire connected to it that goes to the engine ground. There is also one other spade connector on the alternator its a capacitor that keeps electrical noise down so its not heard thru the radio. Here is a picture of it. s-l16001.jpg Its about $6,, Wiring Job is step by step.

There is no wire that runs directly to the battery negative post from the alternator-its indirectly connected thru the chassis ground at the engine ground( the meshed wires).

The red wire coming from the fuse box gets connected to the Positive Battery Post.


Once you have these done, we'll move to the starter and get it sorted out.


Randy

[jbowen944]

Randy, I’ve got the alternator red wire connected, grounded to engine with the brown wire from the mesh cable, blue wire connected, I’ll order that part.

[jbowen944]

Randy, Attached is a picture of my alternator, I've got the toothed nut, the toothed bar, and the adjustment arm. I'm unsure on the order of these, as my bracket has two threaded holes compared to the standard one.Do you know the order of parts for this? Also thank you for the help on this. I'd be lost without it.

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[320iAman]

Randy, Attached is a picture of my alternator, I've got the toothed nut, the toothed bar, and the adjustment arm. I'm unsure on the order of these, as my bracket has two threaded holes compared to the standard one.Do you know the order of parts for this? Also thank you for the help on this. I'd be lost without it.

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No,,,,,The red wire B+ on the alternator is positive must be attached to the positive lug on the starter solenoid-not grounded to the engine ground or this will burn up your alternator.

I have the same toothed bar and toothed adjustment nut. The slotted bar goes on first, then the toothed bar and is secured by a bolt with a special washer to the alternator bracket, the toothed nut with its bolt fits in the toothed bracket, then the bolt goes thru the slotted bracket thru the top of the alternator bushing and is secured by a 13 mm nut.

In fact, yesterday I took out my Alternator and changed out the rubber bushings on the bottom to polyurethane ones--much stronger, the rubber ones were getting chewed up.

Randy

[jbowen944]

I guess i phrased that wrong, the red wire is hooked up to B+, the blue wires are hooked to D+. Brown cable from the copper mesh cable is screwed to the alternator body. For some reason when I screw the bracket and adjustment together, It looks like it might be pulling the alternator at an angle. I'll work on the order of the arms, and see if if it does it. It screws to the middle bolt hole, not the top, correct?

[320iAman]

I guess i phrased that wrong, the red wire is hooked up to B+, the blue wires are hooked to D+. Brown cable from the copper mesh cable is screwed to the alternator body. For some reason when I screw the bracket and adjustment together, It looks like it might be pulling the alternator at an angle. I'll work on the order of the arms, and see if if it does it. It screws to the middle bolt hole, not the top, correct?

Good on the wiring, as too the angle mine does that too, thats why I installed polyurethane bushings on the bottom as the angle is cut down-it harder material and resists the twist,, this has been a problem with BMW since the days of Adam and Eve and has been brought up to them numerous times-that alternator bracket-the bottom holes are not aligned correctly and twist the alternator pulley from being exactly straight to the crankshaft pulley.

The other fix to this is too enlarge the hole going toward the motor and push the securing bolt toward the motor then tightened in-this would counteract the non straightness-then one would have to weld the hole on the side going toward the fender to make it solid or put a shim in the hole to keep the bolt more towards the motor so that the fan belt on both pulleys is straight.

Randy

[jbowen944]

Randy, so now how do I make sure the starter is wired in properly? Also, I’ve got a red cable that bolts to the battery tray with a battery terminal on it, but also the red cable coming from the fuse box, what’s the wiring situation for the battery? Also how can I track down that capacitor you mentioned for the alternator? Flywheel is going in now, freshly surfaced, almost done!

[320iAman]

The short cable from the battery tray-goes to the negative battery post-generally these are colored black, the red cable from the fuse box goes to the positive post on the battery-there is another longer red cable that goes to the start solenoid on the starter to the positive battery post. You can also run a longer black cable from the negative battery post to the engine ground which makes the grounding system much better and is recommended by BMW.

The Capacitor :

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Here $5.99, New/Free Shipping, Capacitor for Bosch Alternator

https://www.ebay.com/itm/Capacitor-f...53.m1438.l2649

Once you have these installed there is only one more connection to get the starter sorted out , its a black wire with a female spade connector -named in wiring diagrams NO. 50- this is the ignition wire that activates the start solenoid which runs the starter motor when the key is turned to the start position-it connects to the 1st male spade terminal right next to the the threaded bolt which has the positive red wire from the alternator and longer red wire-thicker from the positive battery post.

Randy

[GDAus]

Randy, so now how do I make sure the starter is wired in properly? Also, I’ve got a red cable that bolts to the battery tray with a battery terminal on it, but also the red cable coming from the fuse box, what’s the wiring situation for the battery? Also how can I track down that capacitor you mentioned for the alternator? Flywheel is going in now, freshly surfaced, almost done!

This might help

Cheers

[320iAman]

Here is the Bosch SR40X starter for 1980-83 E21's to see actually where the wires go too. No 50-Ignition Wire is in between the threaded bolts next to the partition. The bottom threaded bolt connects the Starter Motor to the Start Solenoid-the top threaded bolt has only the Alternator + wire and the Battery Post + wire.

FYI the other male spade terminal is not used on 80-1983's its a connector to a power resistor if one is running points to keep voltage up in the Ignition Coil for easier start ups. If one connected No 50 to it rather than the NO 50 male terminal it wont not hurt anything--the car would simply not start up as the starter motor would not engage or operate on 1980-83 Models.

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Randy

[jbowen944]

Thanks! for some reason the cable in the harness that runs to the starter from the battery is black on my car! So that cable and the fuse box cable both go to the + terminal on the battery, and the short one that connects to the tray goes to - terminal correct?

[320iAman]

Thanks! for some reason the cable in the harness that runs to the starter from the battery is black on my car! So that cable and the fuse box cable both go to the + terminal on the battery, and the short one that connects to the tray goes to - terminal correct?

Yes, Thats right. Color of insulation is not critical , it makes it easier to trace wires to +/- start and end points.

Randy

[jbowen944]

Thanks Randy, should have it all together now!