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E28 Retrofit Kits are available for purchase!

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Also available for E21

Upgrade your flakey, melty, and unreliable E12, E23, E24, or E28 fuse box.

Address one of the biggest causes of electrical problems in your classic BMW—the ancient and unreliable torpedo fuses. Our kit upgrades your E12, E23, E24, or E28 to modern, reliable blade-style fuses.

• Lower total resistance and won't lose spring pressure over time
• Prevents melty
• LEDs show green for any circuit with power; red if the fuse is missing or blown
• LEDs can be disabled via a switch
• Includes sockets for four spare fuses
• Fits under the stock fuse box cover
• Includes a full set of blade style fuses

IMPORTANT: This kit requires the modification of the fuse box by removing the bullet (torpedo) fuse holders. Once the torpedo fuse holders are removed the new circuit board drops into the existing slots through the plastic.

The "E28 Blade Fuse Box Upgrade Kit" is compatible with

• All BMW E12 models
• All BMW E23 models built before September 1982
• All BMW E24 models built before September 1982
• All BMW E28 models

E28 Blade Fuse Box Upgrade Kit Installation Manual

E28 Blade Fuse Retrofit Kit Install Walkthrough Video

Product Photos:



----------Original post below----------

Hi everybody,
I've been working on a blade fuse retrofit kit for e28 fuse boxes for a number of months now and it's high time I made my own thread about it. I'm very close to a final version and will be posting updates here as progress is made.
I'd like to thank @cek for offering up his cars as guinea pigs - his input has been invaluable for improving the final product.
Quick specs:
Compatible with standard / mini / low-profile blade fuses (no longer applies from 5/28/23 onwards, I had to make a change to support manufacturing efforts)
Works with both Euro and US cars
Lower total resistance and won't lose spring pressure over time
Indicator LEDs to identify blown fuses
Does require modifying the fuse box by removing the bullet fuse holders, but drops into the existing slots through the plastic
Fits under the stock fuse box cover

Here's a photo of the current prototype:


See the installation here.

Let me know if you have any questions.
-Galahad

I have installed various versions of prototypes on all three of my cars now:

- Minerva got the first prototype:


- Maytag got the 2nd:



- And tonight I completed install of the 3rd in Vlad:


I timed the installation on Maytag and it took 2.5 hours, but I was taking pictures and documenting things for Galahad the whole time. Maytag's fuse box was in great shape (no melty). On Vlad, I spent close to 4 hours, but this is because the PO (and a younger me) did some pretty poor workmanship inside of that box that I decided to fix correctly while I was in there, and Vlad had a bunch of melty. I suspect when I put Galahad's final version on Maytag and Minerva it'll take me no more than 90 minutes each.

Here's a Flickr album with all the photos I took documenting both Maytag and Vlad's installs.

https://www.flickr.com/photos/ckindel/a ... 7929876781

I've been giddy about this upgrade ever since Galahad reached out to me to see if I'd test it for him. I've investigated other ways of converting to blade fuses before, including using an E30 and/or E24 fuse box. In fact, I bought a new E24 box for Minerva and was originally going to re-do the wiring harness as part of the build, but decided it would be too much trouble.

Galahad's solution is very well engineered and he knows what he's doing. He seems like a swell guy too; quite unlikely to be an ax murderer or something.

Now that I've installed "prototype V3" my message to Galahad is "ship it". This thing is ready for prime time.

Basic instructions:

1. Remove old fuses and relays.
2. Remove back cover from fuse box.
3. Unplug all wires that connect to the bottom of the bullet-style fuse holders.
4. Remove cardboard color guide.
5. Remove all of the bullet-style holders (destructive operation).
6. Put new circuit board in.
7. Replace cardboard color guide.
8. Plug all wires back in to their original locations.
9. Wire up the LED ground wire.
10. Put back cover back on.
11. Reinstall relays.

Detailed instructions:

1. Verify all electrics work (or not).
2. Cover your fender with something so you don't scratch your paint while working.
3. Disconnect positive terminal from the battery. IMPORTANT!
4. Move out of the way: cruise control actuator, aux fuse box, and anything else that will make fondling fuse box difficult.
5. Remove ground bolt on fender.
6. Remove fuse box cover.
7. Disconnect C101 and relays hanging off the fuse box.
8. Remove two 10mm nuts holding fuse box in place.
9. Put something soft between the fuse box and the fender. Like a cushy towel. This is to protect your fender from sharp bits on the fuse box and to prevent pointy bits on the fender from catching wires as you manhandle the fuse box.
10. Verify you can rotate the fuse box 180 degrees BOTH directions. If you can't you still need to snip some zip ties or free up more wires.
11. Remove all relays from the fuse box (technically you could get away with only removing the horn and high beam relays, but you'll want the rest removed for when you get to the 'going medieval' step below.
12. Remove all old fuses.
13. Unscrew the two Philips screws that were hidden under the horn and high beam relays. DO NOT unbolt the hex nut.
14. Rotate the fuse box 180 degrees towards you.
15. Pop the base cover off. A sharp screwdriver in the gap might get it started. The wires stay with the part you are not removing.
16. You will now see the nest of wires in all their glory. If you see any hacky splices, nicked wires, or other things obviously amiss, note them and ensure they get fixed while you're in there.
17. Unplug the three plugs.
18. Start taking gobs of pictures. You cannot take enough pictures. You will most certainly regret not taking more. This Flickr album may help, but your fuse box may be slightly different. Note, for example how the WH/PINK wire goes to a plug labeled WH/OR and NOT the one next to it that is WH/VI. You'd THINK PINK is closer to VIOLET than ORANGE. You'd be wrong.
19. Start unplugging. Start with the wires that are most accessible (usually those that go to the rear of car) and move to those that were more buried. To remove the wires DO NOT JUST YANK ON THE WIRE. Use the plastic pluggy thing. If needed, use a thin-bladed screwdriver to CAREFULLY pry under the plastic thingies. But be careful to NOT DAMAGE the cardboard color-coding card!
20. You will find rotating the fuse box 360 degrees in the other direction will make getting some of the wires unplugged easier.
21. Take more pictures as you progress and more connectors become visible.
22. Eventually there will be no more wires connected to pins.
23. De-pin the BR wire going to the Horn Relay. It is not strictly necessary to de-pin any of the relay connectors, but removing the pin for the BR wire that goes to the horn relay will make moving the fuse box around easier in subsequent steps.
24. Carefully (like, really) remove the cardboard color-coding card. It is fragile. It is cardboard that was probably made in East Germany before the war. If you tear it a little that's ok, but it IS YOUR GUIDE to completing this project.
25. Rotate the fuse box back so the business side is up.
26. Now it's time to go medieval. The following is destructive and there's no turning back (other than acquiring another fuse box) after this point.
27. Remove all of the bullet-style fuse holders. Use a combination of screwdrivers and needle-nose pliers to rip them out.
28. Some will come out easy.
29. Some will break when you try. Just push the pins through the bottom, or use needle nose pliers to pull them through.
30. Some will have melty associated with them. You'll just need to win the fight.
31. If you break some plastic, don't sweat. The design of the retrofit doesn't care.
32. After removing all the bullet-style holders, use a knife to score the bases of the spare fuse holders. Use needlenose pliers to rip them off. Then use a sharp blade to cut any remaining jaggies down flat (this is IMPORTANT) because the new circuit board may sit too high otherwise.
33. For any of the slots where fuses cause melty, use a file or knife to ensure the slot is clear and the right size.
34. Carefully set the new circuit board on top and CAREFULLY try to get the blades to slide through the slots. DO NOT FORCE IT. If it doesn't go relatively easily some of the melty needs to be cleaned up more. You may also need to CAREFULLY slightly bend some blades to line them up with their slots. Rock it back and forth gently and take your time.
35. Once the circuit board is seated, put the fuse box cover back on. Check to ensure the new blade style fuses are not interfering with the cover. There should be 0.5-1mm gap between the inside of the cover and the top of the fuses. If there is interference the circuit board is not seated all the way (did you leave melty or parts of the spare holders sticking up)?
36. LEAVE THE FUSE BOX COVER ON. Attach it with a screw so it's secure. If you have a pristine cover you may want to find a not-so-pristine cover to do this with... the idea is you'll be protecting the new circuit board from damage when you flip the whole thing back over again and start plugging wires back in.
37. Flip the fuse box 180 degrees so the blades are visible.
38. Put the cardboard color guide on. IMPORTANT: Some cars' cardboard color guide don't have pin slots for all of the pins on the retrofit kit. Use a knife to carefully cut new slots.
39. Fix any wiring crimes committed by POs (or younger yous) now. Use proper tools and splicing methods. Seriously, don't be that guy anymore.
40. Reconnect all the plugs onto the appropriate blades, using the cardboard color guide, your photos, and the following:
41. - If there are two places a wire can go, wires that go to the front of the car, go on the left (towards the engine). Wires that go to the rear of the car go on the right.
42. - Wires with white plastic thingies are "output" from fuses and thus go on the bottom (front of the car).
43. - Wires with black plastic thingies are "input" to fuses and thus go on the bottom.
44. - Wires without plastic thingies go where they were originally (check your pictures).
45. - Start with the front of the car wiring first. Then do rear of the car.
46. Feed the small end of the black wire that came with the kit through the grommet that goes to the front of the car. Plug the little end of this wire into the small blade poking down from the circuit board below where the spare fuses are. This is a ground wire for the status LED circuit. The LEDs will not work (but everything else will) if you skip this step.
47. Once you are done, double-check your photos. If a little voice voiced uncertainty, listen to it. Go back and check the pictures.
48. Plug the three plugs you unplugged above back together.
49. Now test that you did it right.
50. - Rotate the fusebox 180 degrees so the business end is up again.
51. - Remove cover.
52. - Install all relays.
53. - Plug C101 in (you will forget to do this at some point and wonder why the car won't start).
54. - Take a deep breath and look around ensuring you didn't forget anything.
55. - Reconnect the positive terminal to the battery.
56. - Three LEDs should light. If they don't, flip the little switch between the spare fuses and fuse 4. If the LEDs still don't light, something ain't right.
57. - Try to start the car and test that all electrics work.
58. - Assuming it's all A-OK, button everything back up the reverse of above. When putting the fusebox back cover on, there are three posts. If you can't get it to close tightly there's probably a wire interfering with one of the posts.

The hardest thing about installing this thing is ensuring you plug all the wires back correctly. Having tons of photos really helps because even though things are color-coded, the colors don't really match after 35 years.

Any ballpark on price yet?

Looks amazing! Was looking at an e30 fusebox, but this looks much better (both in functionality and ease of installation)
Same question as Dale, what would be the price?
Do we know if this affects the vdrop that plagues several e28s?
Thanks for keeping the e28 alive and supported

Subscribed.

Ju@n wrote: Apr 08, 2021 8:11 AM Do we know if this affects the vdrop that plagues several e28s?

I'll let Galahad comment further, but it should help.

Subscribed here too.

A couple people have asked about pricing - the design isn't finalized so I'm not going to make any definitive comments at the moment.

Ju@n wrote: Apr 08, 2021 8:11 AM Do we know if this affects the vdrop that plagues several e28s?

Yes, this will at least help those problems; the lower total resistance will reduce the voltage drop across the fuse. I'll be taking some data on e28s I can access to better quantify the difference. The fuse box melting is caused by resistive heating due to bad contact between the holder and the fuse, (un)fortunately neither of my cars have this issue so I don't have data for how bad the resistance can be right now.

Very interested, PM sent.

I'll take two, when ready. Mark me down.

Interested.

Beyond interested.

Interested

Very interested. Just waiting to hear at least ballpark pricing. As long as its not astronomical I will surely get one. Kudos to the both of you for this soon to be excellent contribution to the e28 community.

Interested; add me to the order list.

Subscribed.

Looks great!

In for one 100%, two maybe. So so down and excited. No more melty.

Interested for at least one kit. Add me to the list unless they are gonna be one zillion bitcoin...

Mark me down for one.

Mark me down for one as well.

Hi.
Mark me down on 2 please.
Cheers
Sagi

Neat-O, great work from both parties. Might as well have one...The better bullet fuses are getting harder to find.

Local pickup available in MA

In for one as well

Heck yeah! Been waiting- count me in.

I'm interested, but I have questions about the LEDs:
-Do they stay on for unswitched 12V fuses even when the car is off?
-Are they on only when their fuses are intact, only when blown, or a different color when intact than when blown?

RonW wrote: Apr 09, 2021 10:57 AM I'm interested, but I have questions about the LEDs:
-Do they stay on for unswitched 12V fuses even when the car is off?
-Are they on only when their fuses are intact, only when blown, or a different color when intact than when blown?

There's a master switch for the LEDs between the spares and fuse 4 so you can turn them off when you're not using them.
Each LED only turns on when the associated fuse has power - green when the fuse is good and red when it's blown.

Count me in man. I will take one.

I would like 2 please, can you add me to your list?

Colin