Ferrari 328 Fusebox

The Fusebox is located on the passenger side of the vehicle, behind a dashboord cover. The cover is held on by two thumbscrews under the dashboard:- >/p>

Once this cover is removed, the fuses and the relays on the fusebox can be accessed although the top of the fusebox is still behind a bit of the dashboard. This hidden part does cover some of the connectors. Please note the brown wire leading from the relay in the left hand column 2nd down is NOT original, this was an emergency repar when the pin supplying the fuel pump on the left hand connector burnt out, which started my whole investigation into the fusebox.

The main fusebox in the Ferrari 328 has most of the circuitry for the anxilluary devices in the car, taking input from the user controls and then using that to switch the devices on and off. It also includes the circuitry for the fuel pump, radiator fans and key switch. There are other locations for important circuitry in the Ferrari 328, so if you have an electrical problem it may not involve the fusebox.

The purpose of the fuses in the fusebox (like any fusebox!) is to protect the circuitry and wiring of the car in the event of a device drawing too much current, for example in the case of a short circuit. What is supposed to happen is that the fuse heats up and melts, safely contained within the fuse, cutting off the current to the faulty circuit. After the fault causing the high current is fixed, the fuse has to be replaced.

In a good fusebox, any output is protected from being connected to either the negative side of the battery (any part of the chassis in the ferrari 328) or the positive side of the battery (nominally 12V but higher when the engine is running with the alternator charging the battery). Unfortunately this is not completely true in the original ferrai 328 fusebox leading to some nasty problems, more on this later.

There are 23 fuses in my 328 fusebox, all standard (not mini or Maxi) blade fuses. This standard is sometimes called ATO. The values include 7.5A, 10A, 15A, 20A and 25A. The value required for each location is given in the car handbook and on the back of the fusebox cover so I will not repeat it here unless someone specifically asks me. Never replace fuses without checking that the fault that caused the fuse is fixed (if the fault still exists the fuse will just blow again), never replace them with higher values than they should have without carefully considering the consequences and never bridge the fuse with a conductor. If you pass currents that are higher than a circuit was designed for through it, you are risking serious consequences including fire.

The fusebox also contains the relays for the car. I will not include a tutorial on relays here, there are many good ones on the Web. The main purpose of relays is to allow a small current (such as the one you can reasonably put through a dashboard switch or control) to switch a high current (such as the ones required to run a device, for example the headlights). You can also implement digital logic using relays for example only put the headlights on if the key switch is in a certain position and the headlight switch is on. According to my car handbook, there are 18 relays in the Ferrari 328 but this is not true for my car, it has only 17 and a metal connector in a slot designed for a relay. From the location of the metal connector, this is because of lighting requirements in the UK.

There are three types of relay origanlly fitted in the Ferrari 328.

1. A single pole single throw relay, Bosch part number 0 332 014 113, rated at 30 Amps. Note the two 87 terminals on the circuit picture is slightly misleading, there is only one connected to the circuitry in the fusebox.
   
2. A single pole double throw relay, also known as a changeover relay, Bosch part number 0 332 204 101, rated at 20 Amps for the normally closed terminal and 30 Amps for the normally open terminal.
   
3. A twin relay, bosch part number 0 332 015 006.
   

The TYCO catalogue is also a good source of the dimensions and physical pin layout for these relays, Bosch as well as TYCO. Dimensions are in milimeters. Note the bracket attached to the side of the relay is an option for the TYCO relays which you don't want in this application - it wouldn't fit under the fusebox cover.

I also have quite a few of these new relays spare and can get more easily if anyone is interested in purchasing these, cost £2.50 each +P&P at cost, minumum order 6 relays.

The third type of relay is a bit more of a problem and many advertised equivalent relays are incorrect, this is a twin relay where the two made contacts are NOT connected until the relay is energised. I am currently using an unbranded one, which is not ideal. I would like to use TYCO part number v23134-M0052-C642 which is in their catalogue, but I can't find anyone who actually sells them, any ideas?.

Connections to the fuse box are made using plug in connectors. The large physically double but electrically single black connector is the main 12V supply direct from the battery. This connector is good for over 100 Amps and provides a solid power supply for the fuse box. The other connections are made using 8 multi-way white plug in connectors, one on the left, four at the top and three on the right. These connectors are a problem, they are nowhere near substantial enough to carry the currents they are used for. In particular, the fourth connection down on the left hand connector, a beige wire which powers the fuel pump, often heats up and burns out, disconnecting the fuel pump and preventing the car from starting. This happened to my car and is why I have spent so my time examining the fusebox on the 328. I also know of other cases of this. To spot this you need to remove the left hand connector and inspect the white connector housing for any signs of scorching (brown marks). You may need to remove the fusebox (see below) to access the connector. If this is a problem in your car, there is a simple fix. Take the wire from the fuel pump and solder it directly to the correct pin on relay r. The correct pin is pin 87 on the circuit diagrams, the horizontal one at the top.

There is a document that is freely available on the internet titled "Circuiti Elettrici / Wiring Diagrams / Circuits Electriques", the file is often called 1989_328_wiring.pdf. This document gives fairly complete circuit diagrams for 1989 US version 328 cars including the connectors and the internal circuitry of the fusebox. Despite being for a different country and the revised (post-ABS) version of the 328 it seems very accurate for my 328, at least as far as the fusebox is concerned. The black 12V power connectors are labelled A and B and the white multi-way connectors are labelled J, K, U, V, W, X, Y Z as shown below.

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