All Power drops
 

Why guys,

Ok so have found a very strange problem, I wired my starter directly to the ignition to by pass all the OEM wiring mess as I had an issue that when I turned the key all power would drop for a second and then come back. Now that I have by passed all that mess the problem is still there, when I start cracking the motor the power drops to everything for less than a second, ECU, accessories, headlights, etc but keeps on cranking. Battery is good and all fuses are good.

Any idea of what I can look for or do to fix this.

Sounds like a bad contact in the ignition switch to me.

Thanks man, should I try and clean the contacts on the switch or replace the switch?

Probably easier to just replace the switch. Do a search on it. I recall a thread where someone got a "BWD switch" from oreillys or something and it ended up being an OEM part, like in Mazda packaging and all.

Matt

edit Check here

Great thanks man, will give the switch a once over and see if it fixes it otherwise will order one.

Just reading up a bit and looks like my fusible link might be acting up, should I replace the fuses in the link, the main fuse is brand new but the other are a bit corroded.
What do you guys think?

Fuses are either "open circuit" (blown) or they are fine. I haven't seen any condition of corrosion that may cause your issue. Unless you are talking about corrosion in the contacts of the fuse socket, you should look elsewhere.
The likely culprit is the ignition switch. It may be possible for you to remove the switch, carefully disassemble it, and examine the contacts. Clean them, and put the switch back in and try it out. If the problem goes away I would just replace the switch anyways so the problem doesn't come back.

Thanks man, yeah I think Im going to clean the switch and see what happens, also hoping to replace my positive and negative battery cables just to be safe.

Issue sorted, was my positive battery cable, it had a fault in the cable.
Tested a new 0 gauge cable and had no drop in power and all is working when cranking the motor.