Brown Wire Fix / IAP Headlight Relay Kit Questions

[btoran]

I’m about to do the Brown Wire Fix and install the IAP Headlight Relay Kit and have some questions about each.

Brown Wire Fix: I’ve read multiple threads on this and know there is a quick fix (cleaning up existing contacts / terminals) and a not so quick (but better) fix that involves running an additional 10 gauge wire either from the starter to an unused terminal on the ignition switch or fromt he battery to an unused terminal switch on the ignition switch. Since my battery is in the trunk, it's easier (I think) to run the wire through the firewall (assuming I can find a grommet with some space. I know where my ignition switch is (since I put the key into the thing frequently), but where do I find the starter on my 1975 car? Does anyone have a picture of what it looks like, where it is, and what the new connection should look like?

IAP Headlight Relay Kit: After reading the instructions, I THINK I understand how this thing works, but I’d like confirmation, as well as any tips for those that have already done it. I think two new relays (one for the high beams and one for the low beams) gets mounted in the engine compartment and then wires run from those relays to the headlights (through some new holes I have to drill in the headlight buckets) and each gets grounded. Then the existing connection to the driver side headlight gets connected to a small wiring harness supplied with the kit (which in turn runs to the relays). finally, the one of the wires int he kit gets connected to the alternator's + terminal. Is that it? are all the connections made inside the engine compartment with no need to route wires through the firewall to either the ignition or existing light switches?

[4uall]

GOOGLE is your friend

https://www.google.ca/images?hl=en-CA&q ... d=0CB8QsAQ

From the forum http://www.fiatspider.com/f08/viewtopic.php?f=6&t=15314

[aj81spider]

I have not done the brown wire fix, but I'm not a big fan of it. Basically you are just jumpering around the existing wiring to the ignition switch. If the connectors are old and have developed some resistance then that will help improve the voltage to the ignition switch - however so will cleaning the connections.

I put the IAP headlight relays in two different cars (74 and 81). You are correct, all the wiring is in the engine compartment - nothing through the firewall. It's pretty straightforward, and as you described. I had to drill the hole bigger on one set of headlight buckets (81) and was able to squeek the connectors through the other (74). They are grounded to the mounting screws of the bucket. I had a little trouble with that not being a great ground so ended up extending the ground wires and connecting them to ground points in the engine bay. Overall it was one of the best upgrades I ever did to the cars and should someone want to convert back to stock you haven't cut up any of the cars wiring.

[KidDingo]

I did the IAP headlight upgrade on my '81 and found I didn't have to drill into the bucket. I simply used the existing connectors on the headlight and plugged them straight into the IAP harnesses. If I remember correctly, it took a little bit of messing about, but nothing egregious and nothing someone with a fundamental understanding of automotive electrics couldn't manage.I think I had the job done in about 30 minutes.

[btoran]

Thanks guys. That helps a bunch!

[KidDingo]

This probably won't be much use to you, but sometimes a photo can help.

[timspider]

I did the brown wire fix with this understanding (which could be wrong), by running the second wire to the other side of the same connector at the ignition switch, you are sharing the load between the two, not just jumping the original. Seems like a good idea, no?
Did I unwittingly do a bad thing?

[aj81spider]

You didn't do anything bad - and if the car runs better then you probably did some good. The reason I'm a brown wire skeptic is that anywhere else in the car no one would consider just jumpering around the existing wires, but on the ignition switch it is OK.

Technically you are sharing the load - but not much. If you need the brown wire fix it is because you are dropping voltage on the path to the ignition switch. Let's say you are dropping 0.4 volts when drawing 6 amps. That means the wire has 0.066 ohms of resistance. If you put in 12 AWG wire for the brown wire fix it has a resistance of 0.001588 ohms/foot. Say you use 6 feet. That is a resistance of 0.0095 ohms. If I do the math correctly (always I dicey proposition) then the 6 amps of current will split 5.25 amps down the new brown wire and 0.75 amps down the old higher resistance wire. For all practical purposes you've just moved the current to the new wire.

There's nothing wrong with this - but anywhere else in the car people would be saying we should fix the problem, not just jumper around it.

[redcars]

The brown wire fix started at the Fiat factory or more likely with the Fiat electrical engineers. I believe it started with the 79 model. I know for sure that my 81 and 82 models have it. The brown wire is molded on too the battery terminal with the big power cable that goes to the starter. The factory brown wire goes to the open connector on the ignition switch. This cuts the load on the switch in half. Even with the brown wire fix I think the ignition switch is over loaded and as many high draw loads as possible as possible should be relayed.

[aj81spider]

I'm not sure I agree with that. I sold my 81 so I can't go look at it, but when I put ignition relays in (I agree this is a useful modification that unloads the overloaded ignition switch) I remember the wiring as largely the same as my 74 - and the wiring diagrams I created at the time support that memory. I consulted Brad Artigue's wiring diagram for the 80-82 and it looks the same as well.

As I understand it, there are two wires providing power to the ignition switch, a black and a brown - but that was true on early cars as well. One of the wires goes to the 30 terminal and one goes to the 30/1 terminal. These are separate circuits in the switch and power separate parts of the car. My understanding of the brown wire fix is to parallel up the brown wire going to terminal 30. This terminal supplies a good deal of the car as well as the starter output, so is more heavily loaded than the 30/1 side.

I'm happy to be re-educated, but I believe the later cars are no better than the early cars in this respect.

[majicwrench]

Just a note regarding the picture of the relays', they should always be mounted, if possible, with the connector down to help prevent water getting in there.

I'm a sceptic about things like brown wire fixes too.

[4uall]

I had been informed when I bought Fiona that this was the factory brown wire fix I have had zero issues so far

[aj81spider]

That's interesting - I don't remember that on my 81 (but then again I barely remember what I had for breakfast), and it doesn't show up on the wiring diagrams I have.

Do you have three wires bringing power into the ignition switch as well?

I may have to consider myself re-educated.

[spider2081]

Here is a link I feel explains the " Famous brown wire fix"

http://www.mirafiori.com/faq/content/bwfix/bwfix.htm

After reading this link I opened an ignition switch here is what I found.

Yes, there are 2 terminals identified as # 30. Inside the switch they are connected to electrically the same point. So using both # 30 terminals does nothing inside the switch. It does not add another set of internal contacts. Both # 30 terminals are the same piece of brass inside the switch.

The switches I have have push on terminals on the back of the switch assembly. These terminals often referred to as "spade" terminals are known in the electrical industry to become intermittent over time. All the switches I have a have a 5 cavity connector about 8 inches from the switch. This connector (C31 in Fiat diagram) has similar style contacts as the ignition switch itself.

So in my opinion the Brown wire fix
1. Bypasses C31 as a possible cause of intermittent contacts.
2 Adds an additional contact at the switch to share the current flow.
3. Increases the wire current carrying capacity by doubling the existing wire size.
4. Does nothing to improve or extend the life of an ignition switch

Another opinion,
For older OE ignition switches the wires can be soldered to the switches eliminating the spade connectors. The new switch I saw would melt if soldering was attempted.
Properly installed ignition switch bypass relay or relays accomplish much more than the Brown wire fix.

When I purchased my 1981 Spider in 2003 it had an intermittent ignition switch. Without disassembling and cleaning the switch contacts I installed the following relays.
I have installed relays for the headlights, windshield wipers, and starter solenoid.
I have not had a single issue since.

Hope this is some help.

[4uall]

great , now I have to get under the dash and take a picLOL I have no idea. Will try tonight.