Corrosion on 1800E and 1800ES Fuseblocks
First published: Mar 2020  R. Kwas  (Updates and comments on-going!)


Four wire Low Resistance (Kelvin) Testing


Fuseblock of a '72 1800E, located on the driver's footwell.
Picture by Allan H. and used with his kind permission.

On earlier, carbureted 1800s, the FuseBlock, is the terrible Lucas supplied FB, which, because of its construction, is particularly susceptible to developing ever-increasing in-line Resistance, and because of its location under the hood, is also under environmental attack, accelerating deterioration...really a two strikes against situation!

Thankfully, FBs of the later 1800E and ES models, are on the other hand, located the cozy passenger compartment, so they are certainly, under much less environmental attack.  These FBs are because of their location and less susceptible construction, only necessary or recommended to be reworked if they are actually exhibiting green copper corrosion, or voltage drops under load have been confirmed by measurements with test equipment (See:  Reference Information, Four Wire Low Resistance (Kelvin) Test) ...or if they are exhibiting indirect other symptoms of inline resistance, such circuit interaction or other whacky symptoms.  [Such as Lightswitch / Tachometer interaction!  See:  Actually, this was a highly unusual Ignition Sys / Tach interaction!]  

E and ES FBs are of the same high quality, stacked, riveted brass contact construction as the 122 FBs, so they work well for a long time, but eventually can also develop series resistance in the same manner that the 122 FBs develop it (See:  ), only slower, as the deterioration is not aided by poor environmental conditions due to location...of course a poorly sealed Windshield can result in some water raining down on the FB also (if your feet get rained upon when driving in the rain, this water source is well worth investigating before your FB might suffer!).    

If an injected 1800 vehicle has experienced a Fuel Pump power supply failure, due to corroded contacts on the conical fuse-ends on F5 (spinning the fuse in its holder to cut through corrosion remakes the contact and restores function), that is an early indication the owner should most definitely clean conical ends of ALL fuses and reinstall them with ACZP, but again, unless there is a definite indication it needs it, I probably wouldn't advise a complete rework as a general rule.  FBs can certainly be reworked preventatively, if an owner insists, but I am writing this because I don't like being sold something I don't really need (for that, you can go to the dealer!), and I expect most people are of that mind...! 

If you have confirmed in-line resistance (ideally made while passing high current, not just the minimal test current of the Ohms function of a Multimeter [See:  Reference Information, Four Wire Low Resistance (Kelvin) Test]), or simply decide you want your FB reworked as part of a detailed restoration, with the typical fully soldered, absolutely minimum in-line resistance on all connections with all gas-tight-joints, and permanent superior electrical performance(!) of the FB similar to what I offer for the other models, I can certainly offer this service for the 12 fuse 1800E/ES units at $140 plus $30 core charge (which I will be happy to refund core charge when I get your old FB, whole and intact, corroded only, back from you). 



Reference Information:  

1800E Fuseblock, frontview.

Rear-view of FB.  Quality riveted construction similar to that of 122 FBs is apparent,
as are bus-bars, which electrically tie certain power input terminals and circuits together. 

Excerpt of Wiring Diagram ('71 1800E) with FB internal bus-bars highlighted,
 and showing their electrical function.


Four wire Low Resistance (Kelvin) Testing:


Low in-line resistance on the order caused by corrosion, starts at a very low magnitude, but will creep ever higher, and can/will at some point, become significant enough to negatively affect electrical function, but still be too low to measure with even a quality Multimeter.  A special technique is necessary, and should be employed to get a stable and usable reading.  This is called a four-wire resistance Or Kelvin measurement.

I was going to write something up here, but there is no need...this outstanding presentation on YT covers it well. 




Brickboard Thread on Tach and Lightswitch interaction: 

SW-EM Tech Article:  Voltage Drops Cause Inadvertent Circuit Interactions!


Related:, Allocation and Troubleshooting.htm#1800_(E_ES) 


External material sources are attributed.  Otherwise, this article is Copyright © 2020.  Ronald Kwas.  The term Volvo is used for reference only.  I have no affiliation with this company other than to present my experience, and highly opinionated results of the use and care of their products, for the purpose of helping other owners keep their vehicles on the road, safe and reliable.  The information presented is my own carefully considered experience, and can be used or not, or ridiculed and laughed at, (or worshipped!) 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, and future! 

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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