I own a 1980 308GTSI. Trying to get a basic understanding of car wiring so I can trouble shoot and better understand how things work. Tell me if this is correct - The negative battery cable connects to the frame somewhere, and the positive cable leaves the battery and supplies power to the fuse box, right? Each circuit in the car comes off that fuse box with the fuse in between the power supply (battery) and the wire that leads to whatever is being powered. Is that basically how it works? And what about relays? How is the relay different from a fuse? I know - really elementary questions for most of you I"m sure. I'm currently trying to trouble shoot the power leads to my two radiator fans, which have no power, and the fuses are not blown. I tested for current. So, I am assuming that would mean there's a break somewhere in the wire? Can I try hooking the fan directly to the fused side of the fuse box and see if that powers the fan motor? And if not, would I be better off to simply run a new wire from the fused side back to where the fan mounts in front of the radiator? Thanks
Elementary check no 1 - when you turn the air con on does one fan come on ? Elementary check no 2 - at the bottom right of the radiator is the thermal switch - if you short the two terminals with the ignition on do the fans come on ?
First, I don't own a Ferrari, so I can only comment on general things - and yes, it's basically how you describe it. Don't know about the 308, but the starter motor is often not fused because it draws such a large current that the fuse would blow, which leads us to... Two completely different things. a) Fuse - fuses are needed to limit the current that flows in case something goes wrong. If you look at an older fuse, the little glas tubes, you see a small part of metal inside. If there's a shortcut or any fault leading to a high current somewhere, this metal part will melt and thus protect the actual electric system from damage. Fuses are intended to brake to protect other (more valuable) parts. b)Relay - a relay is a kind of electric switch. It consists of an electromagnet/solenoid that actuates a switch. The trick here is: The electromagnet doesn't need high currents to operate the switch, but the switch itself can be made very strong. So imagine you have, let's say, the fuel pump and the battery in direct proximity. Now you want to add a switch in your cockpit which allows you to switch your fuel pump on and off (yes, VERY stupid example). You would have to pull a thick wire (fuel pump needs a lot of energy -> high current) from your battery in the back to the switch in the cockpit back to the fuel pump. Heavy, needs space, and you have high currents flowing all around so to speak, which isn't that good. Now what you do is: Add a relay between the battery and the fuel pump, with the relay's switch part connecting them both with thick cable. Then you pull a thin wire from the relay's electromagnet part to your switch in the cockpit. If you now toggle your cockpit switch, the electromagnet opens or closes the relay switch which controls the fuel pump. Voilà, you can now switch your fuel pump on and off without loads of heavy cable.
Generally, this is correct, but the +12V power path has a somewhat more "wandering" route on your model: +12V battery terminal -to- starter motor "+" terminal -to- 4-way power distribution connector -to- fuse box (via several wires) -to- fuse -to- whatever is being powered (sometimes via a relay). The wiring schematic is shown in your OM so you will find this most helpful (186/80 OM for a US version and 195/80 OM for a standard/euro version). However, if the only thing not working correctly are the water fans, the problem lies in the 4-way connector or somewhere downstream from that. greyboxer gave the first things to check, and briefly putting +12V directly to the water fan motors is perfectly OK to test that they work or not. If the fans still do not run with the key "on" and the thermoswitch in the bottom of the radiator shorted closed, (while still in this condition), try moving the large red (R) wire from the top of fuse #16 to the top of fuse #17 and then over to the top of fuse #18 and see if either or both fan runs (would indicate a bad fuseblock). Otherwise, if you've got a voltmeter we'll go deeper, but in any case, no need to do any custom wiring -- this is fixable.
My car is not a stock 308. It has a 2.8 liter G.M. V-6. Whoever did the conversion disconnected the thermal switch and the fans were wired to run continuously whenever the ignition switch is on. I've owned the car for more than a year, and the fans always came on until recently. I have verified the fans themselves are working, by touching the wires from the fan motors directly to the battery terminals. I also tested the wires that feed the fans by hooking up a new fan motor and got nothing, so I'm pretty sure the problem is with the electrical feed.
Assuming that the fan +12V power source is still the same (the big red wire going into the top of fuse #16), you could also try connecting a jumper wire from the big red wire going into the top of fuse #16 (when you're in the condition where you think the fans should be running) directly to one of the fan motors "+" leads and confirm/deny if you've got +12V power on the big red wire.
Ok, now I think you've hit on something. . The top connections of fuses 15 and 16 are not connected to anything. Both have connections coming off the bottom side if the fuse, but not the top. I assume that both the top and bottom connection points coming off each fuse are fused feeds, is that correct ?
The jpeg shows the fuseblock area from the stock 186/80 (1980 US/NA 308i). The top terminals of fuses #16, #17, and #18 are all connected together by a riveted plate on the backside of the fuseblock (this connection is where the 308 fuseblock problems that Birdman noted usually occur -- i.e., the plastic softens from the I^2*R heating which "loosens" the riveted connection) so on a stock car it wouldn't matter if the big red wire, which is the +12V power to run the water fans (labeled "Cu2.5R"), is connected to the top terminal of any of these three terminals. One of the big green wires (labeled "Cu2.5V") at the bottom of fuse #17 goes to one water fan (via its relay) and the big green/black wire leaving the bottom of fuse #18 (labeled just "VN") goes to the other water fan (via its relay). Can you identify these wires (big red, big green, and big green/black) on your "unstock" 308, and are they still connected to the fuseblock in the stock area? Your not having a wire connect to the top of fuse #15 (in addition to the engine change ) and having the water fans run all the time indicate to me that you've got some serious electrical changes (so I can't help much if it's not stock unless you can describe the configuration). Not quite sure how you define a "fused feeds" so I'd answer your question this way: the top male spades above the fuses are typically the +12V input; however, via the riveted plates, some of these top terminal are connected together so not every male spade will have a directly wire attached. The wires leaving the bottom male spades go off to run whatever they are meant to run so these usually have one or more wires each (and are not connected to the "neighbors"). Image Unavailable, Please Login
Birdman, Are you still selling your fuseblocks? If so, how much, and are these pretty much "plug & play" Thanks Tim
Yes, click the link on my signature. I am not trying to sell you fuseblocks if you don't need them, just suggesting that this is the EXACT circuit (radiator fans) that failed in my fuseblocks. See picture! The is the back of the right fuseblock showing the "bus bar" that connects the three right-most fuse circuits to one +12V supply. Once the plastic melts, the thing is toast, but even before that, you can have a bad connection in the rivet that goes through from the bus bar on the back to the fuseholders on the front. It's basically the most unreliable POS ever designed. Birdman Image Unavailable, Please Login
