Project EXI

The building of a Marlin 5EXi kit car, using a Seat Leon 1.8T 20v Donor
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Mar 09 2010

Understanding how to connect to the donor loom


The wiring loom is still moving forwards. One thing I had to overcome is the power requirements for the fuses and relays, which are now some distance from the battery. In a convential setup this is not a problem, particulary in a front wheel drive, front mounted engine.
There are a number of ways to solve this problem.
Run small invidual cables from the battery, rated at the capcity the device being powered needs.
Run a large cable with capcity to power all devices, with some overhead for future expansion. This route is the more costly route, but in my opinion is the better option, it will allow other devices, such as a radio, electric heater etc, to be added later without the need to add more power circuits.
Given the seat donor also this method, with a 110A interior feed, this is the route the marlin loom will take.This then adds another problem, how to get a 10mm diameter cable to connect to 6.3mm terminal on the fuse box? Simple answer is you cant, so I need to get a battery terminal distribution connector. This two M8 studs, one for a the battery cable, using a 20mm2 M8 connector, the other is for smaller wires, stacked up, but using 6mm2 connectors with an M8 stud. using smaller wires with 6.3mm spades on the end to power the fuses box system.
In total this adds about £15 to the total cost of the wiring, but worth it in my opinion.
So another AES order has gone in, for battery cable, terminal connector, terminals, washer bottle and some slipon terminal id markers.
I have now identified the Mass Air Meter, and associated cable to the ECU. Just one connector left near the Air inlet manifold.
I will create a Marlin loom to VAG loom interface document, so all the wires that need to be connected up are easily identifable. !!
Also to fit the fuse box and relays to the front, it has been suggested to mount all the components onto an aluminium sheet, then mount the sheet to the front bulkhead. That way the switch gear can be removed and serviced outside of the marlin, awesome. Means I can solder inthe warmth indoors :)

Posted by Steve | Permanent link | File under: ecu, electrical