My car is currently running but I am having trouble understanding what wires connect where and how the fuse in the engine bay near the junction box is connected and to what exactly. At this point the wires are a mess and any clarification on what exactly is connected to the fuse near the junction box would be helpful. I can't make heads or tails of electrical schematics but any detailed schematics relevant to 85 that anybody has would be helpful as well.

Basically I've had the car for 9 years and just recently fixed the A/C. I drove 1,000 miles through Texas in the Summer with the A/C on high and had no problems. One of the main power lines going to the junction box on the driver side of the engine bay was not soldered correctly or maybe at all and this was getting hot and pulling away from its mated wire. The mechanic figured this out and also replaced a 20 amp fuse in very bad shape. I do not know exactly what was connected to what but basically he ended up putting most of the car's electrical components online directly with the fuse and as soon as I got home that fuse had blown. I brought it back and he tried to separate out the lines to figure out what was the problem and I told him that this fuse did not need to be integrated with basically everything and that originally I thought there was supposed to be a 25 amp fuse as opposed to the 20 amp he replaced. The fuse is blowing when the A/C is put on 4 and the headlights are on. Being that there is an entire fuse box for almost every electrical part in the car I'm assuming there should not be a fuse between the battery and the rest of the electrical components creating an additive scenario for all devices but I don't exactly know. My other hunch is that the fuse is supposed to protect the computer and should be sitting between the battery and the computer only? Any help would be greatly appreciated as I am blowing fuses trying to figure this out. These images are his first and second attempts at fixing the problem. The first attempt is with all the electrical tape. There is a 20 amp fuse in a hefty black inclosure that is just for a fan attached to the radiator, pay no attention to that. There is currently one 25 amp fuse and one 20 amp fuse that this mechanic has randomly placed along two different lines based on no actual information about the car HELP!

 

stock, there is just one fuse directly off the battery positive terminal, this fuse powers the LH2.2 fuel injection system. I believe it goes directly to the fuel system relay thats under the glovebox, and then from the fuel relay, various circuits go to the ECU, to the injectors, to the fuel pumps, to the MAF/AMM, etc.

however, I think I see *THREE* fuses in the vicinity of your battery. one appears to be on the main circuit to the 'positive terminal' (that flat black square box on the relay bracket on the fender behind the battery).... The Positive Terminal supplies +12V to most everything else in the car except the fuel injection, and the starter/alternator. ... there's no fuse on that wire in the original car, most circuits coming *off* the positive terminal are wired through the main fuse panel. the other one, I have no idea where it goes, fuses like that are often added for things like aftermarket stereos, lighting.

any splices wrapped in electrical tape have no place under the hood of a car, tape will deteriorate quickly in the heat of an engine compartment.

 

Yes, there are three fuses, I should have been more clear. The one in the black fuse holder is not part of the equation and is just connected to an electric fan on the radiator to help the A/C blow colder. Is there any way for me to assess which wire is which? If the fuse is connected to the relay where does the wire coming from the fuse go exactly? To the junction box? Can anybody explain to me which wire is which in the junction box? Thank you! Any Schematics for this year would help. My books are in another state currently in storage.

 

every wire off the positive terminal is red, there's really no way to know whats what. one of the heavier ones goes directly to the ignition key (or on some years, 2 heavier red wires, to better carry more current).

the factory setup had 3 wires on the battery + terminal... the main really heavy one that goes to the starter, a medium heavy one to the positive terminal, and the one to the fuel injection fuse, which then goes through the main engine harness, through teh firewall near the glovebox, and connects to the fuel system relay thats also behind/under the glove box, then that relay feeds everything else (one half of the fuel system relay powers the ECU and stuff, the other half powers the fuel pumps and stuff).


the only good wiring diagrams are the ones in the 'green books' which are out of print, and were model year specific. The only way they are available now is via Volvo Original Technical Publications, on a secured subscription website or a secured USB stick. I have an earlier version of the OTP for the all years of the 240/260 (and another for all years of the 940/960) that was on a CDROM, but is heavily copy protected such that I can't even make PDFs from the diagrams. https://store.otpubs.com/volvo-origi...lication-dvds/