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240z Fuse Box Replacement - Feedback Request - MSA, ST, Etc.

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So my ’71 240z has the dreaded yet common parking circuit contact burn hole. I see that I can get MSA’s updated fuse box for $200 or get a used good condition box with a cover for $100 - $140 shipped. For those of you with the MSA fuse box, does the clear fuse cover still fit over it? So far the few reviews I have seen on the box’s functionality and benefits are very good. Can anyone else speak to the MSA box?

I have also seen the Blue Sea ST line of boxes that look very nice and are very affordable. If I went that route I know I would have to relocate the fuse box. I am thinking either making a custom glove box liner to mount the box or just putting it on the passenger side kick panel, much the like 280z’s had. This of course is not factory and this is where I am on the fence. I know I don't want it under the hood or to be easily seen. So these are my options, pony up at least $100 for a used fuse box but still use 40+ year old technology, pony up $200 and keep the original box location and have much more modern technology, or spend approx. $70 on a ST box and pieces needed to wire it up and relocate the box. No matter which way I go, the original box is outta here!

Fusebox01.jpg

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The MSA boxes are very good quality. They have no provision for the OEM lids to fit however. The curcuit ID's are printed on the circuit board so the lid is not required to remember what's what.

I have BlueSea stuff in my Z, exceptionally good quality. Using the right one gives you not only replacements for OE curcuits but room to grow for future additions. Get the 5032. ST Blade Split Bus Fuse Block - Blue Sea Systems then you don't have to go hacking up the bus bar yourself. One side for IGN/ACC only, the other Hot all the time. Simple. Go get a couple of 6 pin connector blocks from OEM-Type Bullet & Spade Electrical Connectors for 1960's through 1970's Japanese Vehicles... Bridgestone, Datsun, Hodaka, Honda, Kawasaki, Landcruiser, Suzuki, Tohatsu, VW, & Yamaha and make an lovely plug and play replacement.

I would stay away from used OE fuse boxes.

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I have the MSA fuse box and love it. True - the OE clear cover will not fit on the MSA box. Since it is under the ash tray cover I don't consider it an issue. At one time MSA had a cover available but no more. The MSA box had one pigtail connector wrong so I stole the correct one from my old box and transferred it.

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+1 on the link to vintageconnections.com (source jim lists above for connectors) - great stuff at a reasonable price. while i haven't replaced a fuse block, i bought a "professional kit" from them, which includes a great assortment of connectors and housings plus a really nice crimping tool. i've used these plugs on the z as well as on my motorcycles and am very happy with it. the spade connectors are brass and the tool gives excellent crimps - first one i've used that approaches factory quality.

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Here's my side-by-side photos of the OE and MSA fuse boxes. Correction to my earlier post - two connectors were wrong on the MSA: female bullet style vs. OE female blade style - visible in the pictures.

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Great pictures for comparison Jim.

I betting the incorrect MSA connectors are actually just butt splice connectors, where you were supposed to cut your old spade connectors off your old box wiring and crimp the ends of the resulting pigtail wires into those butt splices. No doubt the instructions to do that were MIA....

Sourcing those large spade connectors is tough. I haven't found them yet. Anyone?

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You guys are great! This is exactly the kind of info I needed. I can see the value in the MSA box in the fact it only takes a few minutes to install. Of course the ST box from Blue Sea along with the connectors from JDM Electronics would make a sweet and expandable fuse box solution. Seeing that I plan on putting a Vintage Air system in the car at some point the ST box may be the way to go. Plus, by making some 6-pin connectors if anyone ever wanted to go back to a stock style fuse box they could.

zKars, can you expand on how you went about it building and installing your Blue Sea ST box?

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Just remember to upgrade to a relay harness for your headlights & parking lights! Don't want to melt out the new box.

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I actually use two BlueSea panels. One is a high current 4 fuse panel then 7748l SafetyHub 150 Fuse Block - Blue Sea Systems

This panel gives me the main high current alternator output fuse and whatever I want eventually that's I want high current protected.

Then I have a 12 fuse distribution panel with ground bus terminals, the 5026. ST Blade Fuse Block - 12 Circuits with Negative Bus and Cover - Blue Sea Systems

I cut through the bus bar on the back of the 5026 somewhere along its length based on how many of the 12 circuits I wanted IGN/Acc and how many Constant 12, then ran a fat 8 gauge to the bus bar that I isolated.

Interestingly, I kept the stock fuse block (well, the MSA equivalent) to get me enough fuses for the total system. This puts all the new components on the new fuse panel and leaves most of the stock fuses for stock things, with the exception of Head lights and HVAC which are on the new panel.

Now all this and the bank of relays for all the new stuff (fans, light relays, HVAC etc) and wiring connections to everything are mounted on and around the passenger foot well area

Edited by zKars

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I also put the MSA box on my '71 Z. It installed pretty easily, and was of good quality. I do remember that a couple of the connectors were not right, but I just spliced in the correct ones from the old burned up fuse box. I never had fuse box problems again after that.

Marty

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Thanks for all the feedback guys. Based on everything above I think I have figured out what I am going to do. I am going to go with a MSA box and get Dave's parking light harness and install the headlight relay harness that I already have. Then if I decide to add A/C to the car or anything else I will install a secondary ST fuse box to control power to those components. As brother J.D. would say, "its time to get out tha chuckboooook"

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This is my first contact with the forum. Lot's of great info here, so thanks for that.

My recently-purchased 1973 240Z has the common fuse box melt issue. I am leaning toward the MSA box as a fix, but want to repair the underlying issue(s). Can someone enlighten me as to the "Dave's parking light harness" and headlight relay harness references in this thread?

Thanks in advance.

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The basic problem is that as the car ages... so does all of the electrical wiring in the car, as the wiring ages it starts to oxidize.. as the wiring begins to oxidize, the resistance of the wire increases, and the current passing through the wiring begins to experience higher resistance, higher resistance results in the wiring getting hotter then it was designed to.

This is what is happening with the parking Light circuit, and headlight circuit, current passes from one side of the fuse (The battery, or source side) thru the fuse and then on to the load (the headlights).

the weak links... say the combo switch, and the rivets securing the fuse holder to the fuse box experiences more resistance then it was designed to (the rivet get hot, and melt the fuse box plastic, the contacts in the combo switch degraded) ... the only way I think (not positive).. to totally repair the underlying cause of the problem is to replace electrical wiring with new non-oxidized wire.

What Dave's harness upgrade does is to place a relay into the circuit to take the high current load off of the factory headlight circuit, instead of having say (Just guessing here) 15amps or more of current passing through the factory electrical wiring... only a few milliamps of current is passing through the factory wiring to power up the rely.... and the main current to power the headlights goes through the relay circuit in Dave's harness upgrade.

Edited by peng155

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BvtnDave -

Phil provided an excellent description of Dave's harness benefits. These are really great upgrades for your car and will potentially save your combo and turn signal switches from burnout. So... DO add them to your MSA order for the fuse box, your car will thank you! ;)

Also, change out your old, tired turn signal and emergency flasher cans for electronic units similar to this one: Novita/Hazard Warning Flasher (EL12) | AutoZone.com

These units are available at almost any auto supply store. No more pokey turn signals!

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I know this thread is a little old, but it came up on a search for replacement boxes.  I just installed the headlight upgrade harness (which is awesome and easy, btw!), and noticed that my parking/tail lights were out.  Traced it back to the fuse box--yay.  Saw the cover was head distorted and the inner clip was slightly melted, as was the metal inside the fuse, but the not in the middle where it should have gone out.

So--question is, what causes this particular fuse (and the inner side of it) to consistently overheat?  Have I unknowingly solved the problem with the headlight upgrade?  It seems silly to just replace the box only to have it overheat and fail again because I haven't solved the problem that caused it in the first place.

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The headlight relay harness does not impact the parking lights at all.

I posted this a few years back: 

The best way to keep the circuit intact (IMHO):

  1. Change all of the exterior markers and interior dash bulbs to LEDs. (You will lose the dimmer function unless you change the rheostat to a PWM, but that's a topic for @Captain Obvious to describe.)
  2. Change the 20A fuse to a 10A fuse. (This limits the current and heat build-up.)
  3. Clean the contacts (front and back) on the fusebox. (This should get rid of hot-spots in your fusebox.)
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Time and corrosion that slowly builds on the contacts, creating ever increasing resistance at the fuse/clip contacts and even within the wire crimps at the connectors. This creates increasing heat. Which accelerates the corrosion, which accelerates the heat, etc. That particular circuit operates at a fairly high current level that makes it the first go. 

BTW the fuse selection itself does nothing to limit current, it is just a switch that blows when the current in the circuit exceeds its melt point. Voltage and resistance in the circuit determine the current. V=IR 

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The fuse is a current limiting device by definition. One of the problems with that circuit was that it was designed to have too close to 10A draw, so the engineers selected a 20A fuse to prevent nuisance trips. This gives the opportunity to build up more heat at the fuse clips. At close to 20A, that sucker will glow in the dark. I have seen it.

Using the 10A fuse in conjunction with the other steps I listed will reduce the opportunity for heat to build up to the point of melting the fuse box. If the fuse is blowing at that point in time, it could mean it's time to clean the corrosion from the fuse box and light sockets again.

For owners of 73 and later cars, there is another incentive to drop the fuse to 10A (after swapping over to LEDs). The gauge of the wire at the 9-pin connector on the combo switch is too small to support 20A of current. I had a short at one of the bulbs in the gauge light portion of the parking light circuit. Since the current in the short was too much for the wire, the 9-pin connector was damaged. A properly sized fuse (in this case 10A) would protect the wiring and connnectors.

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Thanks for the speedy reply!  I'll swap those for LEDs, for all the obvious reasons.  Pretty much all that I saw are listed as 1156 bulbs with less than 5w draw--I'm guessing from your post above that the sockets are identical between the 67/89/1156 bulbs--they're just different wattages?

My rheostat is not awesome, so it's no worries replacing that--did you have a recommendation on something that fits easily?  I'm guessing with full LEDs I'll need to swap out the flasher unit as well, looks like that's in the steering column, so I'll find out what will fit there when I take the headlight switch out to clean it.

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57 minutes ago, santamaus said:

Thanks for the speedy reply!  I'll swap those for LEDs, for all the obvious reasons.  Pretty much all that I saw are listed as 1156 bulbs with less than 5w draw--I'm guessing from your post above that the sockets are identical between the 67/89/1156 bulbs--they're just different wattages?

My rheostat is not awesome, so it's no worries replacing that--did you have a recommendation on something that fits easily?  I'm guessing with full LEDs I'll need to swap out the flasher unit as well, looks like that's in the steering column, so I'll find out what will fit there when I take the headlight switch out to clean it.

Are you referring to LED or incandescent bulbs for 5W draw from an 1156 bulb? Phillips lists the incandescent at 26.9W. The wattage of the different types of incandescent bulbs are listed in the spreadsheet I attached to the post in the other thread.

There is not a ready replacement for the rheostat. The bulbs I used aren't overwhelmingly bright, so I have no need to dim them.

If you replace the turn signal bulbs, you will need to replace BOTH flashers. I have been using these for 5 years: https://www.amazon.com/gp/product/B011BTMDQM There is one on the driver side under the dash, and the other is on the passenger side.

 

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Yes--LEDs, I saw a range of about 2W to 5W, mostly depending on lumen output.  I knew there were two flashers, I didn't know they where in two different places.  Did you end up just bypassing the rheostat and bridging the two sides?

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I just put the rheostat on the lowest resistance, and I leave it there.

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