Rewiring an 86 GTV

[GTVeloce]

I've never been happy with the electrics on the GTV (no big surprises there!) Both the design was badly flawed plus the use of poor connectors/wiring size etc. So a year ago I started to re-wire the car. I have kept some of the exisiting wiring (and the original fuse box) but generally it is new. A big part of the project was a redesign of how the system works plus adding a number of upgrades. I have finally virtually finished with just a few remaining touches to go but critically, the car drives again.

The number of changes/modifications I have made are too numerous to mention but a few of the major bits:
I have increased the number of relays used significantly and as such now have three fuse boxes. Like I said, I have kept the main fuse box under the dash but now it has relays for the starter solenoid, electric windows, interior blower fan, AC cutout when starting, heated rear screen (but this just feeds another relay), interior lights, headlights warning buzzer, directions indicators and ignition.

In the boot is another fuse box with relays for heated rear screen, rear fog light, fuel pump and windscreen washer bottle pump.

There are two 'loose relays' under the dash for the central locking and the electric fan and water pump controller.

In the engine bay there is a new fuse box with relays for the horn, headlights, high beams, AC, engine fans and low speed fan control.

Some of the upgrades I have made include;
- electric water pump
- electric controller for fans and water pump (PWM) allows me to set what temperature I want the engine to maintain
- replaced the resisters for the internal blower fan with a PWM controller
- central locking
- addition of a lights timer kit to keep internal lights on after doors close for a pre-determined (and adjustable time)
- extra internal lights under dash
- all LED lights inside and out including headlights
- relocated windscreen washer to boot
- added a boot light activated via a reed switch so it comes on automatically when the boot is opened
- added a pair of amps to run the sound system
- relay that switches the AC off while the starter motor is engaged so I don't have to turn it off to start the car
- added a charcoal canister and solenoid from a 156 to wash the petrol tank fumes

I have replaced all the connectors that are exposed such as engine bay and headlight connectors to Deutsch connectors.

Redesigned the main power circuit such that power from the battery passes through a kill switch then heads direct to the starter motor. From there, it passes through an ANL fuse which then branches to 1) alternator, 2) engine fuse box and 3) interior fuse box.

The upshot of all this work is that everything on the car is working better than it ever has done before! And it is just using a 65amp alternator. It should also last a very long time. I have tried to make everything very discrete so it is hard to see a lot of the work done and the car presents very originally. For example, I used a potentiometer to control the PWM device for the blower fan which I modified so that it would fit where the original fan switch goes and the original knob fits over it.

The last few things to do are;
- I am going to try and add a circuit breaker straight of the battery before the starter motor as I hate the idea of such a long run of cable with no protection. Not sure if the starter will draw too much but it will be easy to remove if it doesn't work.
- I am going to add a PWM device to control the engine fans. The electric controller I have allows for PWM of the water pump and controls the fans but only with on/off control. I have a design that will allow me to use the Mazda controller to engage the fans at a lower speed (whatever I choose but I'm thinking 75% to start) and then have an old school thermal switch in the radiator set to a higher temperature that when activated (i.e. the fans at 75% aren't enough) switches the fans to run at 100%. This controller includes a nice soft start feature to limit current in-rush at start-up.
- I have thought about extra relays for the windows in the doors but currently the speed is so good I'm not sure it's necessary! We will see.

I am also in the (slow) process of building a 3L V6 to go in this car (currently runs a TS engine) so I haven't touched most of the engine wiring as that will happen with the new engine.

[Anth73]

Well done Julian!

Which Mazda fan controller are you using? I was able to use a Nissan / Mitsubishi controller on my GTV6 with an inline resistor to set the initial turn on speed to around 50%.