MoTeC Global Forum

I've been working on a project car for a few years now (89 Supra I hope you are reading Figgie!) and will be commencing on the wiring soon.
One thing I'd like to do is get rid of the fuse box in the engine bay, and while relocating it is one option, the PDM seems the better option.
Having read the threads in this section it seems most people are doing a rewire of a whole car of wiring a race car from scratch, I'm not the best with wiring yet so I'm trying to get a feel for what is the best approach to this to make the most efficient use of the PDM, and if possible use a 15 rather than a 30. Is it just a case of wiring the PDM to the plugs that normally go into the fuse box and switching the PDM outputs with the signals going into the fuse box?
One thing I notice is that there are a few high current circuit breakers and relays in that fuse box , 60, 80 A etc so that will chew up alot of outputs.

Sorry if this is a broad question but any tips are appreciated

A PDM would commonly be used as part of a complete vehicle re-wire.

I beleve that trying to retro-fit a pdm into a car with a factory wiring loom, replacing the relay and fuse setup would be just too difficult (though not impossible).

I would recommend this:
write down a list of the electrical components that the PDM will have to control. For example.
Starter Motor
Wiper
Indicators
Tail lights
low pressure fuel pumps
high pressure fuel pumps
brake lights
ECU
ignition
Dash
radio
shift lights
Fans
pumps
etc
etc

When you have this list, count how many items you need to control, and see which PDM will be enough to control your car. Sometimes, you can combine items to use up less outputs. Perhaps watch the PDM webinars to get more info on this.

Once you decide what to do, then you would remove ALL wirng from the car, and make a complete new PDM loom based on the list above.

then add to this an ADL loom (if required) and an ECU loom.

It is a big job, but the end result will be a car that is lighter, more controlable, and more reliable.

-Jamie

I'll look into this some more bearing in mind what you have mentioned.

I remember that one fuse was for the horns, another for the interior lights etc and a 60A fuse was for the ABS

There is a harness that runs from the drivers side kick panel, out to the rad support, across the rad support and then to behind the pass side headlight to the fuse box and battery. I am going to get a spare one of these harnesses and remove all the redundant wiring, then look at either relocating the fuse box or explore the PDM option more. My idea was to recreate this loom with a PDM in place of the fuse box and relays

I'll have a look at the wiring diagrams to see what is actually supported by each fuse and relay and also get a list together of what it is I need to run in the front of the car.

I do have an M800 and SDL combo, and the battery will be going in the boot area. I plan to PWM two fuel pumps however I am happy to run these straight off the battery with a fuse as its geographically easier.

The main issue I see is the few high current circuit breakers chewing up alot of outputs but if I wire all the systems individually that may actually use more outputs, need to think about it some more

Thankyou for the advice provided thus far, gives me some direction to proceed with this

I can see using a PDM for the wipers, turn signals, various fans, auxiliary pumps, etc, that all get switched either often by the driver, or often switched controlled via the ECU etc.

Can One not put the ABS on a relay and have that triggered by one of outputs - which would take ~1/2 of SFA to do?