The remaining two large multi-pin relays do not energise but they do show ohm resistance numbers
Okay , your relay layout is not dissimilar to mine , though i do appear to have at least a couple more relays . It's at this point we begin travelling into unknown territory , and so i'm gonna lay out my suspicions as to what i think each does . But i would also like to add a caution at the same time here , the following is based on theory and logic , none of this is actually backed up by fact . An examination of the relay layout is on my list , but i've simply not had time to actually do this to date . So i would urge you to treat this information with caution .
Now a little back ground here . A relay is little more than a high voltage switch . It's prime purpose is to protect lighter core cable from damaging high voltage , the type of voltage that would convert a light wire section to a light bulb . They also enable more fancy switches to be used , and by that i mean the type that sell cars (most people buy on looks , not technical achievement) , however they do make wiring more complicated . Though a few switches do have a maximum capacity of 10 amp , the vast majority are only capable of handling around half that , about 5 amp . Though relays seldom fail , you should never completely ignore them , i have actually replaced only two in 40 years of motoring , and believe it or not , one wasn't actually on a vehicle .
Something else i would add , is the Italians were famous for their electrics , though many , may say it's more infamy . I don't know if that still stands , but i do know older electricians are loafed to work on Italian electrics . They simply don't do electrics is the most common answer , and have a notorious reputation for this among the older mechanical circles . Now , i will say in their defence , i've not found anything too bad on my vehicle , so much so , that i would vote them higher than the Germans . I've ragged out numerous cables and connections for rerun , and reconnected those fitted by Hymer . Probably the worst i've found is the connection into the d+ wire . A scotch clip and heavy section cable joined to a very thin section wire that was threatening to break it , like really ? .
Right so looking at your last photo , we have a general relay layout , lets deal with that first . Pretty much in the centre of the layout , you're showing 3 relays which all look similar 12v , 20a . They look light tan , but on my vehicle are actually black . My research discovered they are available in several colours , which is common with most relays . It could be classed as an identification issue .
I believe two of these are for your head lights . Now if my information is correct H4 bulbs are rated at 50/65w , which equates to around 5 amps a piece , maximum wattage , totalling just over 10 amps in total . This would be perfectly within the limits of a 20a relay , but the problem here is both headlights would be connected , whereby they are fused separately . It's a mystery as to why they are fused separately , but this could be some kind of redundancy feature , quite common on heavy trucks . So i suspect each headlight has it's own relay , as there would be no point fusing separately then feeding the same relay . The third grey relay i suspect could have one of two functions , the fuel pump , or rear fog . All three relays are standard 5 terminal 20a , with a Lancia part number and listed as either headlight or fuel pump . However as it is a mandantory requirement for at least one rear fog light to be fitted on all vehicles post 1986 , i list this as well . This is one of few areas i have investigated , as i had a problem with my front fogs . I found a broken wire in the engine bay with no obvious purpose . On tracing it back until it terminated , i discovered it was the earth for the front fog relay . Beside it was the rear fog , so i know both these circuits have relays , and where they are . But lets not forget the fuel pump , as this is also likely high powered and for obvious reasons , powered continuously .
Now the faded black relays . These are also standard 5 pin , but with a higher 30a capacity . I suspect these could be main beam , and again two because they are fused separately . Faded black ? could be an indication of extensive use . Is your vehicle high mileage ?
So now i'm gonna throw these two in here , starting with the black relay you've removed . This is interesting as the unit appears to have rather a lot of connections , and that leads me to suspect this could be more than just a simple relay . An internet search revealed the part number is generic though out Italian motors including Maserati , but is helpfully listed as just ignition , with no further clues . The one exception is Maserati , who list it as part of the heater system , so it could be something to do with the heater blower , but this is a bit sketchy at best . We should not forget this is a very high amperage circuit , up to 30a in fact , and the wiring from the dash control is nowhere near heavy enough to carry this type of amperage , making a relay here a necessity . To be honest , my first thought was your windshield wiper relay , but a further problem here is mine is actually under the bonnet . Mounted pretty much where your wiper motor is , on the fire wall . I can't tell if yours has a similar layout from the photos , but i suspect not , as access would be poor . I do have to add my wiper motor has been moved as part of the Hymer conversion , so i have exceptional access to these relays . There are 2 relays in this position of which one is a 6 pin and basically twice the height , of say one of those 20a relays . I can also add , i've found evidence that suggests it's quite common for this unit not to respond in the usual manner , which further suggests this may not be a relay in the usual sense .
So now that brings us to the Orange relay , and yes i also have one of these too . It's actually an Alfa part number , and due to it's colour , screams either indicator or hazard unit . Modern practice is to combine these two functions now , so likely supports both . There is a significant amount of wiring to the switch , which appears to be replicated on this relay , the exception being the switch lighting . Lets not forget with the four ways working , including the repeaters , the system is consuming something like 94 w , though just on a matter of fact here , my van is closer to 136w . Either way it's too much for a switch to handle , making a relay also necessary . This is slightly further reinforced as you state you can't activate this again , it's technically not a relay .
and so that leaves us with the blue relay , and i also have one of these too . I've left this to last , because , well to be perfectly honest i'm not really sure what this is ! . My first thought was , with it being blue it's has something to do with water , or perhaps cold , maybe the fridge ?. I knew it couldn't be anything to do with the cooling fans , as i had already found these relays under the bonnet . However my suspicions were blown apart , after i discovered the fridge relay maybe part of the internal workings of the EBL electronic management system fitted in my van . An internet search revealed it to actually be a Fiat/Lancia part number , further making a fridge relay even more unlikely . This left me at quite a loss as to what it could be , frankly i did (and still do) suspect it could be part of the heater system , but if the new information is correct with the black relay , that would mean two relays on this system which is even more unlikely . I could be convinced that it may be something to do with a glow plug start system , but i'm pretty sure i also have one , and i have flame start . The wiring really does need tracing to figure this one out
