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General car electrical question - replace fuses or not?

Help, Advice, Owners' Discussion and DIY Tutorials on Volvo's stylish, distinctive P2 platform cars sold as model years 2001-2007 (North American market year designations).

2001 - 2007 V70
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scot850
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General car electrical question - replace fuses or not?

Post by scot850 »

I am slowly working my way through the electrics on the 07 C30 T5. One thing I found is that the engine bay fuse and relay box was missing it's cover. The interior looked crusty, so I removed all the large square fuses and the relays. 2 of the relays were showing signs of corrosion on the undersides. However they are the foglights and some other not major item. So while corrosion was present they pins were not burnt or too bad. I cleaned all the relays, sprayed all the contacts in the box with a Wurth contact cleaner which is pretty strong. I then cleaned all the contacts using a fiberglass pen to get them all shiny. Finally I blew out the contacts in the box, used No-Ox-it on all the contacts and refitted.

Today, I decided to tackle the mini-fuses in the box as they looked like they were dirty and had been sprayed with dirty water:

Fuse area of main fuse box
Fuse area of main fuse box

I removed all the fuses (after taking the above picture for fuse value and position reference) and this is what I found:

Fuse corrosion
Fuse corrosion

All the 10-12 fuses were like this or worse. I have removed them then and cleaned then all with a fiberglass brush so they now look like this:

Fuses after cleaning
Fuses after cleaning

I have soaked the fuse box contacts for the fuses in the Wurth contact cleaner and I'm leaving them the ferment for a few hours before blowing out and remaining residue and fluid with compressed air. My 2 questions are this:

1) Even though the fuses have cleaned up pretty well, would you re-use them or just use new ones. I have a box of cheap mini-fuses for our 06 XC70 as emergencies, but would I be better off using those or reuse the old one ok. In both cases I will brush the contacts with No-Ox-it.

2) I have as mentioned left the contacts for the fuses in the box soaking in contact cleaner. Should I clean the contacts mechanical some how? If so what should I use? Normally I'd use a toothbrush but due to the design and position of the box, it is hard to get into the contacts as they are countersunk:

Fuse box contacts
Fuse box contacts

These are what the 2 relays looked like. The others were lightly oxidized:

Relay corrosion
Relay corrosion

Appreciate any guidance from you electrical boffins please!

Neil.
2006 V70 2.5T AWD Polestar tune
2000 V70 R - still being an endless PITA
2006 XC70 - Our son now has this and still parked in our garage
2003 Toyota 4Runner V8 Limited
2015 Kia Sportage EX-L - Sold
1993 850 GLT -Sold
1998 V70 XC - Sold
1997 Volvo 850 SE NA - Went to niece in California - Sold
2000 V70 SE NA - Sold

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jonesg
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Post by jonesg »

wow, what about the computer ?

Vova585
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Post by Vova585 »

https://www.amazon.com/Electrical-Termi ... 7898&psc=1

That's the idea about how to clean pins inside.i would be slightly worried about corrosion entering inside the relays or corrosion too much inside the fuse box in the areas where it is hard to see or reach. Possibly can consider just replacing all the relays from the donor after the main issue will be fixed.
I am bowing to the titanic work you are doing. You will sure emerge like the most knowledgeable person of C30 on this forum. Much respect

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Blacklab467
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Post by Blacklab467 »

You can buy a set of jewellers/ watchmakers flat files that are less thick than the fuse tabs. I would find some files and clean them up that way.
2003 XC 70 (sold)
2007 XC 70, 1970 Dodge Charger R/T.

scot850
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Post by scot850 »

I ordered a set of files as per Vova585's suggestion as well as some di-electric grease. I swear I keep buying that stuff and I can never seem to find it!

Actually, the Wurth cleaner did an amazing job and the connections were really clean after leaving for an hour or so.

All the fuse engine bay main fuse box relays and fuses were cleaned, as well as the pin connectors, particularly the fuses that were bad.

All the grounds (7 of then in total on the 2 strut towers!) were removed, including the main engine ground, cleaned to clean metal and connector ends before Ni-Ox-it brushed and refitted. All now nice and shiny, including the battery terminals.

I tried using the ignition key turned to II as per Volvo instructions, but still don't get it, especially when the DLR lights come on. So nice spark again with the ground connected to the battery. Car fired up immediately and idles nicely after short cold start higher RPM's.

Tomorrow, I will move the car into the larger garage to allow the passenger door to be fully opened and the CEM checked and cleaned. I suspect there might be corrosion from a leaking sunroof drain on that side.

Neil.
2006 V70 2.5T AWD Polestar tune
2000 V70 R - still being an endless PITA
2006 XC70 - Our son now has this and still parked in our garage
2003 Toyota 4Runner V8 Limited
2015 Kia Sportage EX-L - Sold
1993 850 GLT -Sold
1998 V70 XC - Sold
1997 Volvo 850 SE NA - Went to niece in California - Sold
2000 V70 SE NA - Sold

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abscate
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Post by abscate »

I’ve had a persistent problem with my REM fuses in my 2005, every two years I have to clean fuses or I lose taillights. I’ve been pulled over a couple times for this. I’ve replaced it with new , pulled and cleaned every fuse , but they see, to develop the dark oxidation over 24 months of use. I wonder if I should spring for a modestly priced Volvo fuse over aftermarket, perhaps there is an alloy difference
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1999-V70-T5M56 2005-V70-M56 1999-S70 VW T4 XC90-in-Red
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scot850
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Post by scot850 »

Modestly priced Volvo fuse................? :roll:

That would be a first for sure!

I just cleaned all the fuses with a fiber glass pen. They came up real nice and clean. I came to the conclusion that mush of the black on the fuses is actually meant to be there. It is I think an anti-oxide coating. When you push the fuse home for the first time it only scrapes away the contact area. If that is the case then I just ruined them all as I cleaned them all, then De-Ox-ID'd them, before refitting.

It is probably just my imagination, but I'm convinced the lighting is brighter! :roll: :lol:

I think there was somewhere in the region of 50 fuses or more.

On the relays, I have this cheap AliExpress relay tester for 4/5 pin relays. All is does is cycle the relays maybe 6 times or so and then if all is good give you a green light. I had some from a P2 that all failed, actually would not even test. Then the P80's for the most parts are not testable as they have countersunk pins which the tester can't deal with.

All the relays passed fine. Now would they pass still after the car is hot? No idea. I guess if issues continue, then I may have to take that tester along with me as well as a DVM.

Neil.
2006 V70 2.5T AWD Polestar tune
2000 V70 R - still being an endless PITA
2006 XC70 - Our son now has this and still parked in our garage
2003 Toyota 4Runner V8 Limited
2015 Kia Sportage EX-L - Sold
1993 850 GLT -Sold
1998 V70 XC - Sold
1997 Volvo 850 SE NA - Went to niece in California - Sold
2000 V70 SE NA - Sold

scot850
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Post by scot850 »

I forgot to add. I did open both of the corroded relays and internally they were pristine.

Neil.
2006 V70 2.5T AWD Polestar tune
2000 V70 R - still being an endless PITA
2006 XC70 - Our son now has this and still parked in our garage
2003 Toyota 4Runner V8 Limited
2015 Kia Sportage EX-L - Sold
1993 850 GLT -Sold
1998 V70 XC - Sold
1997 Volvo 850 SE NA - Went to niece in California - Sold
2000 V70 SE NA - Sold

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abscate
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Post by abscate »

I once pulled all the relays on the 99 and found dark burned pins on all of them. No running symptoms but didn’t like, so I cleaned them all to shiny metal
Empty Nester
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1999-V70-T5M56 2005-V70-M56 1999-S70 VW T4 XC90-in-Red
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BlackBart
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Post by BlackBart »

"To FUSE...or not to fuse....." That...is the (original) question.

In my very old car, I'm going with good quality new fuses, keep the olds for spares. It has 8 fuses, all 10A. That's the way cars should be!
ex-1984 245T wagon
1994 850T5 wagon
2004 XC70 wagon BlackBetty

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