Some Fiat Electrical Basics: Part 3 A better solution

[zachmac]

NOTE: I take no responsibility for work you or someone else does on you car and the results. I have taken every precaution I can think of to get all this right but I cannot control the actions of others.

Part one of this series laid out some Fiat Spider electrical basics. Part 2 applied that knowledge to the use of a replacement Lada ignition switch. This part will discuss an alternative wiring approach that can both extend the life of a stock SIPEA switch and make use of a replacement Lada switch without making the sacrifice of creating new UNSWITCHED loads.

In part 2 of this series I recommended wiring a replacement Lada ignition switch just like a stock SIPEA switch. However this does change the behavior of the Switched (Situational Needs) loads (see Part 1 for def.). In this section I will tell you how to either simplify the wiring even more and further extend your ignition switch life (Option 1 below) or better yet how to get the Switched (Situational Needs) back to behaving as switched loads while still increasing ignition switch life

Option 1: improving the life of your SIPEA of Lada ignition switch but living with previously Switched (Situational Needs) loads now becoming UNSWITCHED loads

After wiring my Lada switch the way I describe in Part 2 of this series I realized I could further simplify my wiring and reduce the load on the ignition switch by doing this: don’t connect anything to the INT post coming off the ignition switch. Normally this post is connected to the BLUE/blk wire that feeds the Switched (Situational Needs) loads going to the fuse box. Instead just run a new medium gauge feed from the starter main post (like the BROWN wire) to the connection point on the fuse box where the BLUE/blk wire from the ignition post connects in the stock wiring. Basically you are making all those loads UNSWITCHED. I wouldn’t do this if I was running a stock SIPEA switch but if are going to run a Lada switch wired as I suggest in Part 2 of this series then why not just go the next step and eliminate these loads form the ignition switch completely since the Lada switch wired the way I suggested would cause them to behave as UNSWITCHED anyway.

I would run a new wire from the starter versus just jumpering the black feed from fuses #9 / #10 input to the #2 fuse input (factory UNSWITCHED feed) as I don’t want to overload that feed. BTW, if you have a working SIPEA switch this is still worth considering as again it removes all the current for those loads form the ignition switch. The downside is they are now UNSWITCHED so you have to make sure you turn off the lights / wipers / heater blower independent of the ignition. Option 2 below fixes that issue for both a SIPEA and a Lada switch and I think is what I am going to do.

Option 2: improving the life of your SIPEA of Lada ignition switch and NOT having to live with previously Switched (Situational Needs) loads now becoming UNSWITCHED loads

The final solution to help extend your SEPIA switch life or make the Lada switch last while also getting all the loads to act like a stock wiring setup I to run a new feed from the starter to the #2 fuse as described in option 1 above BUT to do it through a relay that is triggered by the 15 post on the ignition switch. This moves all the main power going to the headlights / wipers / heater blower motor off the ignition switch but keeps all those loads working as SWITCHED loads. You reconnect the BLUE/blk wire on the ignition switch to the #15 post versus the INT post and use it as the relay trigger wire. This requires joining the BLUE/blk and PINK wires together. BTW, the vendor supplied the Lada switch already wired this way but for use as the main feed without a relay which I discuss the weakness of in Part 2 of the series.

You disconnect the BLUE/blk feed wire at the #2 fuse input and again, make it the trigger feed for the new relay. Power from a newly routed hot feed from the starter / alternator hot point comes into the relay main in and feeds from the relay main out to the #2 fuse input previously occupied by the BLUE/blk feed from the ignition switch.

While this may seem complicated it is very doable if you are mildly electrically adept. If you are forced to run a Lada switch I think is the best overall solution. If you are running a stock SIPEA switch I think it is worth doing UNLESS you have already installed relay kits for both you headlights and wipers. If you have both of those already done then the current through the ignition switch has already been minimized (except for the heater blower motor) and it is not worth the effort IMO.
Hopefully this is helpful? I’ll be posting a final Part 4 to just run through a review of what power goes into and what loads come off of a typical Spider fuse box fuse by fuse.

[wetminkey]

Cool,...
And this part of your writeup describes how to return the altered ignition circuits back to a stock-type state after wiring in a replacement ignition switch,...perfect. Might do it one of these days,...but I usually leave the keys in the ignition, so I'm good for now.
Again, nice writeup. Thanks.