Fuses, Allocation and Troubleshooting                                                                                                9 /2010/ R.Kwas

Note on Picture Credits:  I’ve included pictures in this article of other’s vehicles, which were kindly contributed to me in response to a Brickboard request for them, including permission to post.  I do not give picture credits to the photographer because I didn’t originally attach the photographer’s name to the picture files.  I have since changed my system to remedy this.  It is now my practice to include the photographer’s name in the file name whenever possible.  I thank contributors for their picture files, and permission to repost them.  If you see a picture of yours used here and wish to be given credit as the photographer, please send me a note and I will do so. 

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Background:  The Fuseblock is the electrical distribution center and heart of a vehicular electrical system.  It needs to be clean and be free of dirt or oxidation.  Fuses should also be held snugly held in their holders, allowing current to flow unimpeded.  Any contamination or looseness will make poor connections and result in nuisance faults a driver can do without!  I highly recommend Anti-Corrosive Zinc Paste applied to clean holders and contact points for a long-term trouble-free service, and the reader can find much information around the SwEm site in support of this! 

 

Fuse and Load Allocation Compilation:  The following tables are presented to help with locating the trouble when an electrical function fails to work on your vintage Volvo.  The simplest check to perform first if possible is to try if other functions on the same fuse circuit are also non-working (one therefore obviously needs to know how the fuses and load circuits are allocated).  Checking for other functions on a common circuit is also recommended as the immediate course of action when the dreaded AMP Indicator comes ON full in your Amazon, while you were just driving along minding your own business!  The following fuse and load allocation tables are intended to help with this. 

If another load on a circuit supplied and protected by a given fuse is also not working, the entire protected circuit is likely unpowered and fuse for it should be checked.  If the other loads on the same fuse work, and only one load supplied by a particular fuse is exhibiting problems, its controlling switch and wiring should be checked (note that included in the term “wiring” may often be a connection to and current path through vehicle chassis, and that the wackier the problem symptoms, the more likely it is that a compromised chassis connection is involved...because poor connections to chassis can result in connecting circuits together, which normally have little to do with each other!).  LINK to:  An explanation of “Whacky Electrical Symptoms” and “Whacky Electrical Wiring?”. 

444 (6V)
544/210 (12V)
122 (12V)
123GT
140
1800 (P,S, not E or ES)
1800 (E, ES)

ADDITIONAL
7X17mm (Shorty) 25A Fuse Notes and Options
Understanding the information an open fuse can give
Corrosion Caused a Blown Fuse

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Tables are presented by vintage Volvo vehicle / Location of Fuse Block / Number of Fuses / and Special Notes are included.

Fuse Numbers are listed from top down, where applicable.  To be certain, its always a good double-check to verify the wiring color codes against the associated wiring diagram.  The consistency of the color codes with the wiring diagrams for these vehicles is quite good.  It’s also a good idea when working on electrical issues, to have an enlarged wiring diagram confirmed to be suitable for the vehicle in question.  Remember the General Rule:  The color code is you friend!

Fuse Allocation Tables are listed by Power Source / Fuse Number / Fuse Type / Size / Current Rating / Load(s) supplied by fuse

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444 (6V) / Firewall in engine compartment / 6 / Screw clamping is used on wires.  These should all be free of oxidation and secured snugly with a dab of ACZP at the contact area of set-screw to wire-end and also, on the threads of the set screws!.  Also, rivets which connect the screw-clamp to the fuse links are susceptible to corrosion (I’ll try to add a detailed pic of this sometime) and making a poor connection (but this is really a fuseblock rework issue beyond the scope of this information).  Be advised that if relative motion is possible, a poor connection exists, and should be eliminated!

LINK to WIRING DIAGRAM used to derive this chart: 
 

 Power Source

 Fuse Number

 Fuse Type

 Size

 Current Rating

 Load(s) supplied

[IGNition Power]

F1

ABF

7X17mm

25A

/ Heater Blower motor, Till Bakŕe Fläkt ??  [translation needed!  Please help identify this load!]

[IGNition Power]

F2

ABC

6X25mm

8A

Directional Indicators

[IGNition Power]

F3

ABC

6X25mm

8A

Wipers

[Battery Power]

F4

ABC

6X25mm

8A

Brake Lights, Courtesy Lights

[Battery Power]

F5

ABF

7X17mm

25A

Headlights, Marker Lights, Instrument Lights

[Battery Power]

F6

ABF

6X25mm

8A

Horns (incl. Relay when fitted)

 
FIGURE 1.
  444 (6V) FuseBlock Fuse 1 on the right...but I'm not so sure as there are three shortie fuses installed! 
Picture Credits to Tom P. 


FIGURE 2.  A second 444 (6V) FuseBlock.  Notice the differences between this and FIGURE 1.
including the fact that the two heavy gauge wires come through the firewall above the FB here and below FB in
other FIGURE 1.  This reinforces the point of double-checking the color codes whenever possible.  Picture Credits to Keith J.  
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544/210 (12V) / Firewall in engine compartment / 4 / Standard flat spade terminals are used to receive push-on crimp terminals (riveted assembly used on these is same as that used on 122 and this design and fastening technique is susceptible to contact problems due to oxidation with age, problems due to this are covered here:  LINK to The Gas-Tight-Joint

LINK to BB thread:  If I understand this correctly the Fuseblock was associated with the system voltage...in other words, a six volt system had the horizontal mounted six fuse FB, and the 12V system had the vertically mounted four fuse FB. 

LINK to WIRING DIAGRAM used to derive this chart: 

 Power Source

 Fuse Number

 Fuse Type

 Size

 Current Rating

 Load(s) supplied

[IGNition Power]

F1

ABF

7X17mm

25A

Directional Indicators, Heater Blower motor, Wipers, Brake Lights, Oil Pressure Indicator, AMP Indicator.

[IGNition Power]

F2

ABC

6X25mm

8A

Horns

[Lights Power]

F3

ABC

6X25mm

8A

Parking lights Instrument Lighting (by way of Dimmer Control)

[Battery Power] 

F4

ABC

6X25mm

8A

Courtesy Lighting, (Momentary) Headlight Signal


FIGURE 3.   544
(12V) Fuseblock with a modern 25A fuse installed instead of the ABF 25A shorty.  Picture Credits to:  ?? 


FIGURE 4.  210
(6V) Fuseblock.  Picture Credits to:  ??

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122 (12V):  Vertical panel near hood hinge in engine compartment / 4 / Standard flat spade terminals are used to receive push-on crimp terminals (riveted design and fastening technique of contacts is susceptible to contact problems due to oxidation with age, problems due to this are covered elsewhere on the SwEm site. 

LINK to WIRING DIAGRAM used to derive this chart: 

 Power Source

 Fuse Number

 Fuse Type

 Size

 Current Rating

 Load(s) supplied

[IGNition Power]

F1

ABX

7X17mm

25A

Directional Indicators, Fuel Gauge, Heater Blower motor, Wipers (incl. Washer motor), Brake Lights, Oil Pressure Indicator. 

[IGNition Power]

F2

ABX /

6X25mm

8A

Brake Lights, Horns, Backing Lights. 

[Lights Power]

F3

ABX

6X25mm

8A

Parking lights, Instrument Lighting (by way of Dimmer Control)

[Battery Power] 

F4

ABX /

6X25mm

8A

Courtesy Lighting, (Momentary) Headlight Signal

Note:  Cigarette Lighter is IGNition powered but unfused.  Since it is a high current load which if it fails could damage the IGNition Switch, if you keep it and use it, it might not be such a bad idea to fuse it with a 20A inline fuse. 


FIGURE 5.  122 (12V) Fuseblock Showing a temporary modern 25A fuse holder installed, also soldered rivets.  It's looks pretty good, but is definitely not a SwEm reworked FB because the link between right side of Fuse 1 and 2 is not tinned and bridged with solder...and there's no ACZP in sight!  Picture Credits to:  ??

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123GT:  Vertical panel near hood hinge in engine compartment / 4 / These are the same riveted contact style FBs used on the 122 which are susceptible to contact problems due to oxidation with age, problems due to this are covered here:  LINK
A second Fuseblock is located on inner fender.  Be aware that the two FBs, although similar in appearance with cover in place, are electrically configured differently (this is immediately apparent when inspecting the fuses…the main FB No. 1 has the beloved 7X17mm shorty fuse, and FB No. 2 has all 6X25mm longies), so they may not be interchanged during restorations!  

LINK to WIRING DIAGRAM used to derive this chart: 

 

 Power Source

 Fuse Number

 Fuse Type

 Size

 Current Rating

 Load(s) supplied

Fuseblock 1

 

 

 

 

 

[IGNition Power]

F1

ABX

7X17mm

25A

Directional Indicators, Fuel Gauge, Heater Blower motor, Wipers (incl. Washer motor), Brake Lights, Oil Pressure Indicator, Tachometer, Overdrive Solenoid. 

[IGNition Power]

F2

ABX /

6X25mm

8A

Brake Lights, Horn (relay only), Backing Lights. 

[Lights Power]

F3

ABX

6X25mm

8A

Parking lights, Instrument Lighting (by way of Dimmer Control)

[Battery Power] 

F4

ABX /

6X25mm

8A

Courtesy Lighting, (Momentary) Headlight Signal

 

 Power Source

 Fuse Number

 Fuse Type

 Size

 Current Rating

 Load(s) supplied

Fuseblock 2

 

 

 

 

 

 

F1

ABX

6X25mm

8A

 Engine compartment, Trunk Courtesy lights.

 

F2

ABX /

6X25mm

16A

 Driving Lights

 

F3

ABX

6X25mm

8A

 Spare

 

F4

ABX /

6X25mm

8A

 Horns


FIGURE 6.  123GT (12V) Underhood area showing  both Fuseblocks.  Yellow is normal and similar to be basic 122.  Green is additional FB supplying and protecting horns, lighting, and those handy underhood and trunk lights as can be seen on the partial wiring diagram below.  With cover removed, it can be seen the additional FB has only normal sized 7X25mm fuses.  Photo Credit (and credit also for a very clean example of a 123GT!:  Ross S. )


FIGURE 7.   Partial Wiring Diagram of 123GT, showing Fuseblock 2.
 

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140  (Early, carbureted) / Behind removable panel on lower center of dashboard /

LINK to WIRING DIAGRAM used to derive this chart: 

 

 

 

 

 

 

PIc OF 140 INSTALLATION:
FIGURE 8.  140 Fuseblock

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1800 (P, S, not E, or ES) (P, S, non-injected) / Electrical panel on inner fender in engine compartment, / Two separate FBs are used.  A double FB contains the important Fuses 1and 2, (Battery and Ignition Power, respectively) and a single FB contains the less important Fuse 3 (Parking Lights…that’s it!  See:  IMPORTANT ELECTRICAL SAFETY NOTICE 1!).  Both are Lucas automotive aberrations with known reliability issues, so I highly recommend at the very least reworking or replacing...especially if you have suffered from inexplicable intermittent electrical problems
Links: 
Gas-Tight-Joint Part II
British vs. Swedish Automotive Electrical

IMPORTANT ELECTRICAL SAFETY NOTICE 1.  Thanks to Lucas, the circuit for Fuse 3, a circuit in which less than 4 Amps flow, originally had a 35A rated fuse specified...so not only can it be said that they produced products of poor quality, but their engineering was also really baaad!  See also: SW-EM Technical Bulletin No. 4:  Owner’s Manual and wiring diagram call for a 35A fuse in the Fuse 3 location.  This is crazy!  Installing a fuse of this rating will allow much more current to flow, than the 14ga. wire is capable of safely handling.  This is perhaps more questionable automotive electrical (non-)wizardry courtesy of Lucas…  You will notice referring to the 1800E / ES information, that on this vehicle, fuses 11 and 12, rated at a mere 5A each protect these circuits with similar loads, so consistent with this, I strongly recommend replacing this fuse with an 8A or 10A rated one, which will clear and protect wiring in case a fault current ever flows.  When this is done, the fuse rating and level of protection will be more appropriate (and similar to a 122). 

LINK to WIRING DIAGRAM used to derive this chart: 

 Power Source

 Fuse Number

 Fuse Type

 Size

 Current Rating

 Load(s) supplied

[Battery Power] 

F1

3AG

1 1/4" X  1/4”

35A

All Battery Power loads:  Headlight Signal (Momentary), Courtesy Lights, Horns, Brake Lights, Oil Pressure Indicator. 

[IGNition Power]

F2

3AG

1 1/4" X  1/4”

35A

All Ignition Power loads:  Fuel Gauge, Heater blower, Directional Indicators, Wipers (incl. Washer motor), Brake Lights, Backing Lights, Tachometer,

 

[Lights Power]

F3

3AG

1 1/4" X  1/4”

35A Way Too High!
See: IMPORTANT ELECTRICAL SAFETY NOTICE 1!  SW-EM Technical Bulletin No. 4

Parking (Marker) Lights, Instrumentation Lighting (by way of Dimmer Control).

 

 

IMPORTANT ELECTRICAL SAFETY NOTICE 2::  You will also notice that the Overdrive (Control and Solenoid) are IGNition powered, and unfused...this is not such a good idea, given the high current load of the solenoid and propensity of Lucas LINK  electrical equipment to fail in the most spectacular ways without prior warning (many of which result in the vehicle being able to be spotted by infra-red detecting satellites from space!).  Adding a fuse of 20A in series with the solenoid circuit is also highly recommended here!  An in-line type would do nicely!

 

PIC OF 1800 INSTALLATION:
FIGURE 9.  1800 Fuseblock

 

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1800 (E, ES) / Left side footwell of passenger compartment / 12 / These FBs use a similar corrosion susceptible, riveted construction as those used on the 544, 122, and 140s, but as they are located in the relatively cozy passenger compartment, corrosion problems at the rivet connections are a lot less common…they can still occur, but much later than those occurring in the Amazons.  However, they are certainly also susceptible to corrosion at the contact ends of the fuses themselves.  When this occurs, particularly on Fuse 5 (supplying the Fuel Pump), the condition is a true show stopper!  Assure clean conical fuse ends on ALL fuses and keep it that way over the long haul with ACZP!  LINK:

LINK to WIRING DIAGRAM used to derive this chart: 

 

         
 

F1

ABX

6X25mm

8A

Heater blower

 

F2

ABX

6X25mm

8A

Wiper (incl. Washer motor)

 

F3

ABX

6X25mm

8A

Cigarette Lighter, Overdrive.

 

F4

ABX

6X25mm

5A

Tachometer, Voltage Stabilizer (supplies Fuel Gauge, Oil Temp, Coolant Temp. Gauges), (Momentary) Headlight Signal.

 

F5

ABX

6X25mm

8A

Fuel Pump, C Enable (Relay 61)1

 

F6

ABX

6X25mm

8A

Horns, Backing Lights

 

F7

ABX

6X25mm

16A

Unused Spare

 

F8

ABX

6X25mm

16A

Rear Window Defrost  See Note 1.

 

F9

ABX

6X25mm

8A

Brake Lights, Emergency Flashers, Clock

 

F10

ABX

6X25mm

5A

Courtesy Lights, (Momentary) Headlight Signal

 

F11

ABX

6X25mm

5A

Parking Lights (Left), Instrument Lighting (by way of Dimmer Control)

 

F12

ABX

6X25mm

5A

Parking Lights (Right, Center-Rear)

Note 1.  This relay allows the significant load current of Rear Window Defrost only when IGNition is ON (and alternator is presumably on-line and able to supply the significant load current).

PIC OF 1800E/ES INSTALLATION:
FIGURE 10.  1800E/ES Fuseblock

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ADDITIONAL: 

“Whacky Electrical Wiring”  

If you have ever accidentally cut through the extension cord while trimming the hedges, and blown a fuse / tripped a breaker (this is strictly hypothetical, I don’t have any practical experience with this, honest!!) ...and found, in this rather indirect manner, that the bedroom was wired on the same circuit as the garage…because the alarm clock was flashing the next time you looked at it, your experience might cause you to question the sanity and/or qualifications of the electricians who wired the house. 

This is an example of multiple unrelated loads in very different locations, on one circuit.  It is quite common and is done for a number of reasons, none the least of which is saving wire and fuses…it is possible, but it doesn’t necessarily mean the electricians were drunk and disorderly. 

Similarly in a vehicular electrical system, it may mean that seemingly disassociated loads are combined on a particular fuse.  Here, the reason is often to even up the total current such that fuses of similar ratings can be fitted. 

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7X17mm (Shorty) 25A Fuse Notes and Options

Blowing Fuse 1 on a 122: 

25 Amps is a substantial current magnitude*, and a fuse of that rating requires significantly more than that to blow open…so if you blow that shorty Fuse No1., you can be fairly certain that there is something quite wrong!  Before maybe blowing another of these semi-precious gems, it’s a very good idea to locate and remedy the cause!
If you were working on your Wiper Switch at the time and the Red wire touched the dashboard with a big spark, you (should) have a good hint as to the cause!  This is a valid clearing of a fault current, so you can go ahead and plug in a replacement fuse (having learned the hard way to work more carefully on live circuits, or maybe to make them not live in the first place before doing electrical work!)...but fuses can also open for less obvious reasons...like having gotten gradually weaker with the corrosion of time where the element was finally not able to pass a normal operating current...this is called a “nuisance blow”.  A “nuisance blow” can be defined as any time a fuse opens without an actual fault current level having caused it.  While working to locate the unknown cause of the fuse blowing, it is a good idea to install a modern fuseholder with a 25A fuse as shown above in
FIGURE 3 and 5, and keep a few of the modern fuses on hand. 

*  ...to give you an idea of how much power 25A in a 12V system can develop, multiply the current times the 12V system voltage, and compare the resulting of 300Watts to more familiar equipment at home...that’s three 100W light bulbs (or one and a half Easy Bake Ovens!)…a substantial amount of power!

An open fuse should always be closely inspected in order to learn as much as possible about the cause of the open from what is left.  Evidence left in or on a fuse which opened when a “hot” wire dropped on the dashboard will look a lot different than the one which opened due to less violent reasons!  LINK to:  Understanding the information an open fuse can give you.

Replacing Fuse1...Options...listed in the order of simplicity: 

1.  Replace the fuse with a replacement from your on-board spares, after remedying cause of fault current, or determining (and making an Executive Decision) that nothing is amiss, and a “nuisance blow” was the cause (you may be sorry!).  Refer to:  LINK Understanding the information an open fuse can give you.

2.  Install a bypass jumper, if a 7 X 17mm 25A fuse is not available (or during troubleshooting, or while waiting for a replacement to arrive).  Wire a modern fuse-holder with a 25A fuse installed, and connect this to temporarily to pass the Circuit 1 current and protect it.  See:  FIGURE 3 and 5 above.

3.  Install a 25A fuse in the more readily available 7X25mm size, after first modifying the Fuse 1 position to accept this style, by bending the left (or right) contact tab to accommodate it.  I don’t particularly like these solutions because they are a bit too rustic/violent for me and also arguably non-reversible, but present them here for the sake of presenting the entire list of all solutions known to me…and showing some creative thinking!  I wouldn’t perform them on my own vehicles as a rule…but  in a “pinch”, I would certainly relax my "keep-it-original attitude" somewhat (totally if necessary!).  Part of the reason I like vintage Volvos is because the original design and materials, with just a bit of tender loving care beyond abundant neglect, prevails against all odds!


FIGURE 11.  7X25 25A Fuse installed into Fuse1 position after first bending
left (Beryllium Copper) spring terminal to accommodate the 25mm fusebody. 

 
FIGURE 12. 
Permanently modified right (brass) terminal to
accommodate a 6X25mm 25A fuse in the Fuse 1 location.
This modification requires
irreversibly bending the terminal, also drilling a new hole in the terminal to capture the conical end of fuse. 
Picture Credits to:  Jim Hekker

4.  Installing the conductor (fusing) element from a 25A 6X25mm fuse onto a 7X17mm ceramic body! 

Harvest the replacement element from the more easily available 25A 6X25mm donor fuse.  Unlike the somewhat uncommon 7X17mm shorties, 6X25mm 25A fuses are much more common and available just about anywhere Eurofuses can be obtained.  Using the donor fuse’s element assures the correct current rating, no muss, no fuss.  Install this onto the shorter ceramic form. 


FIGURE 13.  A 7X17mm ceramic with the element from a 6X25mm 25Afuse installed. 
This solution would work just dandy!  Picture Credits to:  Bladerider  


FIGURE 14.  Another example of a shorty fuse with an element of its full-size brother installed. 
The assembly fits and functions nicely!  Picture Credits to:  simplesimon 

 

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Understanding the information an open fuse can give, how to interpret it, and what action to take: 

Condition       Interpretation           Example        Recommended Action           Comment

1.  Condition:  Blown "wide open", with black soot and tiny globes of molten fuse element plated on inside of glass envelope, or stuck to the ceramic form.  Interpretation:  Fuse was passed a very high amount of current (short circuit!?) quickly vaporizing much of the element.  Example:  A power wire was dropped onto dashboard, resulted in an instant of Smoke, Fire and Brimstone...oops!  Recommended Action:  After that green dot burned into your retina finally goes away, maybe you should leave the power source disabled while finishing what you were doing...or Comment:  This is why we use fuses, but:  "...maybe you should let that nice young man at the gas station with the pony-tail wire up your new stereo!"

2.  Condition:  Barely blown...with a tiny break in the fuse element barely detectable, possibly even only with magnification:  Interpretation:  Fuse passed just over its rated current for a while, or Example:  Another load was added to a circuit, and fuse rating was not considered and increased up to accommodate.  Sometime later, the temperature increased and a nuisance-blow resulted.  Recommended Action:  Reconsider operating conditions of load, recalculate total typical operating current, possibly increasing current rating of fuse.  Comment:  This is the trickiest situation, because a judgment call is necessary. 

3.  Condition: Barely blown...with pitting around the tiny break in the element.  White spots of corrosion are present on fuse element in places.  Interpretation: Fuse passed just over its rated current for a while, or area weakened by corrosion finally gave up the ghost (one of the downsides of living near the coast!)  Example:  Recommended Action:  Reinstall replacement fuse with ACZP! ...even a minimal film on the fusing element itself will keep the salt air from attacking the metal. 

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Related Links:

http://www.brickboard.com/RWD/volvo/1294830/120-130/just_blew_2_25amp_fuses.html

http://www.brickboard.com/RWD/volvo/1517969/120-130/fuse.html

http://www.brickboard.com/RWD/volvo/1441801/120-130/dashboard_green_light_dark_amazon.html

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This article is Copyright © 2012.  The terms Volvo, Bosch are used for reference only.  I have no affiliation with either of these companies other than to present my experience, and highly opinionated results of the use and care of their products here.  The information presented is my own, and can be used or not, or ridiculed and laughed at, at the readers discretion.  As with any recipe, your results may vary, and you are, and will always be, in charge of your own knuckles! 

You are welcome to use the information here in good health, and for your own non-commercial purposes, but if you reprint or otherwise republish this article, you must give credit to the author or link back to the SwEm site as the source.  If you don’t, you’re just a lazy, scum sucking plagiarist…so the Boston Globe wants you!  As always, if you can supply corrections, or additional objective information or experience, I will always consider it, and consider working it into the next revision of this article...along with likely the odd metaphor and maybe wise-a** comment. 

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Corrosion Caused a Blown Fuse?

I read in a wellmeaning, but misinformed (and mis-informing) posting:  (paraphrased) “the blown fuse occurred because the corrosion resulted in more current being needed to be pushed through the circuit…” (or something to that effect).

The poster had the first part right…that association between an over-current and a blown fuse right…unfortunately there remains a large hole in the remaining logic…corrosion in (series with) a circuit typically makes the current less (because it increases the total load resistance).  For this reason, and Ohms Law, the current is typically less, not more.  In the event that corrosion occurs from an energized terminal or connection and presents a path for current to the mounting surface (chassis), for any actual current to flow through a corrosion bloom is rare and if it were to flow, minimal in amplitude at best, certainly not enough to bring the current to an overload magnitude. 

To clarify, a blown fuse can rarely be attributed to corrosion present.  Certainly the corrosion should be eliminated (and prevented from returning/continuing) during troubleshooting, but it did not cause the blown fuse…keep looking! 

Related:  An oxide bloom on a length of wire caused a steadily decreasing cross-sectional area and therefore decreasing current-carrying ability…this resulted in an increase in the heat generated when current was flowing, which eventually compromised (heated and melted!) the insulation to enough of an extent, to lead to a contact between an energized conductor and a chassis conductor causing Smoke Fire & Brimstone.  LINK:  740 Harness Failure and Flameout Notes

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B A C K !