As long as it's all taken apart...

[rbbailey]

OK, so I've pulled the wings off the IIa specifically to replace the brake lines and probably a master cylinder, but I'm going to be doing some basic rust work on the footwell on the driver's side, and some major rust work on the passenger side. With all this going on, I figure I should get other stuff done while I'm in there.

Question:
How crazy is it to think of rewiring the whole truck? I want to put a 2m mobile in, as well as a CD player, cabin lights, rear work lights, and some IPF's. Everything electrical works, but I get a heavy draw when using the heater or lights. Should I be looking for a fix to this issue, or if I'm going to be putting all the new stuff in anyway, should I just start fresh?

Any pointers would be great, whether you have ideas about fixing the heavy load on the system, or on how to actually go about doing a full rewire.

[rejeep]

I would personally...
make sure you have a deep cycle battery
Delco alt convert
and throw in a separate 3-5 fuse panel and not throw it on the original LR system..
Painless makes a decent one..

[jac04]

I wouldn't bother re-wiring the whole vehicle. As long as everything works, I wouldn't even bother with a Delco alternator conversion (assuming you have a decent alternator to begin with) or a deep cycle battery (assuming you won't be operating all your electrical equipment for long periods without the vehicle running). The "heavy draw" is due to the fact that the factory wiring does not use relays to power things such as the heater or lights. You can easily add simple relay circuits to power the heater and lights (fuse each one as close to the battery as possible).

[Momo]

Question: How crazy is it to think of rewiring the whole truck?

It's not crazy at all for what you want to do. The OG wiring on all these trucks is now brittle and weathered, not fun to work with. I've never used Painless but a lot of people like it. You could also go with an new OG style harness and customize it with the proper color coded wire stock, put everything on relays, add a fusebox, etc. Make it scalable. You can hide a fusebox and quite a few relays behind the instrument panel of a IIA.

[109 Pretender]

Relays are control devices and have absolutely nothing to do with the amperage draw that a "load" such as lights and heater motors place upon the wiring system. Relays are traditionally used to remove the higher current for the load from the operator'S control - usually a switch. Relays also allow the use of a 'small' switch in the instrument panel for size convenience. The switch then controls the relay (solenoid operated switch designed to handle larger current draws) which has HD contacts to 'switch' the load-ie lights).

Yeah, LR could've used more relays... but then, the KISS principle predicates simpler is usually better. That might be debatable since English vehicles are "problematic" concerning wiring issues...

Two very important points concerning the British vs American car industries - #1. British use fast blow fuses - American cars don't. Use Lucas fuses at proper rating ALWAYS. If not, then go ahead and use a nail cause you're gonna have problems otherwise... #2. British use smaller wire ga. for a given load vs American, rest of world. Why? Because they use fast blow fuses to compensate.

Keep this in mind when rewiring. A complete rewire is always nice, but yours is working ok now, right? The extra stuff will require wiring of course and I'd plan accordingly. You can be as simple or exotic as you want and time, money & talent permits. You will need an alt. if you are still running a gen. (Gen. only puts out around 30-40 amps max and that's above 1500rpm. Gens don't charge much at all on idle).

My 109 runs on a 120 amp alt. w/front and rear A/C and heat, 4 aux. lights, stereo, CB, 2nd set of brake/running lights in rear, Halogen headlamps, 2 speed wiper and blower mtrs, plus extra gauges, etc. I built a totally custom harness using factory clear Lucar connector boots and factory color coding. The entire system looks factory because it was made exactly Wiring and parts were purchased from R.I. Wiring - they carry everything to do job properly. I run a second set of fuses (Lucas fuses and block from an MGB which is identical to a SIIA fuse block) for a total of 4 on the firewall. I wired 2 inline fuses for the headlights and another for the a/c compressor. I haven't ever had a fuse blow or any other wiring related problems at all.
I deviated from the original wiring on the heated windscreens because the factory wired a single relay to 2 switches to control the heating elements (seperate for each side). The factory design does not allow the relay to operate properly as relays are designed to be used. I used 2 lucas relays instead and wired the resistor element on each screen to a relay individually.

Plan out your ideas and draw up a wiring diagram. Put special emphasis on good gnds and where you are getting the power from. Then craft up your harness and lace it up with electrical tape. (R.I. also can make up custom harnesses and they also do the cloth lacing for the older LR's - mine was 40% cloth insulated wiring 60% PVC w/PVC tape lacing originally). I wouldn't use cloth insulation or lacing unless it's for a "garage queen". Terminate w/good connectors. Ck your old Lucas bullet connectors - female type tend to get old and break inside the blk. rubber tube. Use stock color codes where possible - makes troubleshooting much easier later, if needed.

Good Luck!

[TedW]

You might consider just replacing the rear harness.

It's easy to do; I replaced mine a few years ago after it fused together, went "toaster" on me and started smoking.

This harness can have a lot of wear from having a half-century or so of sand and road debris blasting away at it. Hence the problem.

[Momo]

Relays are control devices and have absolutely nothing to do with the amperage draw that a "load" such as lights and heater motors place upon the wiring system.

What I think jac04 meant was this... when you've got all your current running through one switch (like the combo ign/light switch in an early IIA), adding accessories can overload it quickly. That switch was only designed for 14 amps or so... 2 amps here, 3 amps there adds up quickly. Relays will save the switch by assuming the load. They have their place.

[jac04]

^^At least someone understood my point.
I agree that the amperage draw doesn't change, but the wiring system carrying the amps will change. The best thing I ever did to my SIII was to add relays to power the headlights. Now my headlights don't dim every time the signals flash.

[109 Pretender]

jac,

If your headlamps dim when turn signals are on, it's probably a gnd issue. Whenever you introduce an electrical item like a relay into a system that never had it you actually SLIGHTLY INCREASE the total amperage draw for that leg of the circuit. Let's say you had a wire with a battery on one end and a lamp as the load on the other. No switches at all. There would be a very minimal voltage drop that is a function of the wire gauge and total length (wiring resistance). It would be very, very little loss from battery to lamp assuming proper wire size. 12 volts in - 12 volts to the lamp.
An average automotive switch in generally good condition will produce about 0.5 volt drop through the closed contacts of the switch. Why? Because the switch contacts have more internal resistance across the contacts than the short section of wire that it replaces. So now you have 12 volts in and only 11.5 volts going to the lamp after the switch. In order for the voltage to remain the same the amperage draw must increase.

The best way to view the functionality of a relay is to view it as a remote controlled switch. The relay contacts should switch the high current line and the coil of the relay is controlled by the remote switch on the dash.

Most relay contacts have about as much resistance as a regular manual switch. Adding in a relay to the circuit will add to the resistance of the wire that takes current to the load. It should be minimal and not a problem. As resistance increases in a system, voltage will drop and it will take more current to maintain the original voltage levels.

The best thing here is that analog systems like LR wiring are relatively tolerant of fairly wide voltage/amperage changes - but we still see and feel the effects - lights dimming, heater blower slowing down - until we exceed the amperage rating for the fused circuit which then opens and acts as a safety valve to prevent the wiring from melting.

Most automotive wiring problems are ground related. Bad gnds increase overall circuit resistance which causes big voltage drops and increased amp draw - that's when the smoke begins...

I do agree and it's certainly correct that you don't want to overload Lucas headlamp or ign. switches - they aren't very good when brand new!

Don't get me wrong - what you did is a good thing - any improvement in wiring systems is a good thing if its British (Italian too!).

My point was that the relay does not lessen the load requirement of the headlamp circuit. The amperage requirement is strictly a function of the lamp filament material and what amperage/voltage ratings are needed for it to function properly. A perfect system would have no loss - that doesn't exist. ALL components between the lamp (load) and the power source actually reduce the avail power because of resistance - unless it's a FLUX CAPACITOR - but they only use those on Jeeps

[Les Parker]

Furren wiring

Anyone work on Renaults or Citreons? The wiring on those make an MG look stellar!!

[jac04]

Whenever you introduce an electrical item like a relay into a system that never had it you actually SLIGHTLY INCREASE the total amperage draw for that leg of the circuit.
...
My point was that the relay does not lessen the load requirement of the headlamp circuit.

How is this possible in my example of the headlight circuit of the factory wiring harness? If the headlight circuit is no longer supplying power to your headlights, the only thing it needs to do is power the coil of the relay. How can the amp draw in the headlight circuit increase at all? Are you saying that a relay requires more current than a 55W headlight? Please educate me more on this subject.

Edit: I think our disconnect is in how we are each looking at the headlight circuit. I'm looking at it as only the original factory wiring used to power the headlights (not including any added relays). I believe you are looking at it as everything required to power the headlights (original factory wiring plus additional relays & wiring). From your viewpoint, I understand how the total power required for the headlights can be increased from the additional total system resistance.

[Terrys]

Any of the aftermarket headlamp relay harnesses I have seen get their switched voltage from a seperate, heavier wire, usually run to the battery or solenoid terminal, and the original headlight circuit is only used for switching the relays. The total current draw remains the same, or very slightly increased only by that nneded to operate the relay coils, but the headlamp load is taken off the original, and in the case of the Land Rover, marginal wiring. Without an alternator of sufficient capacity, pulling the load for the healights will still load the capacity of the battery/charging system as it was without the relays. The reason the headlights are brighter is most likely from the fact that the switched wire in the relay system is sufficiently heavy that voltage drop is minimized.

[rbbailey]

Thanks for all this info, I'm going to have to read through it all and make my decision.

I've got some rust on the pass. side foot well, right under the heater motor, that I need to fix. And the brake issues, of course, so I'm trying to figure out what MORE to do -- this is where the electrical comes in.

I know what relays do for switching... but based on some of the comments here, I'm wondering if a properly wired set of IPF's would cause the same type of draw that the headlights and heater cause. Either way, I do have a fuse box and all the wiring harnesses and good switches for all the new stuff.

Can any of you give me some ideas for an interior light that would work for both soft and hard top use?

Edit: By the way, it does have an older Delco alternator that seems to be doing the job, but may not be enough amps for what I want to do.

[TeriAnn]

With all this going on, I figure I should get other stuff done while I'm in there.

That phrase has always been my undoing and has always lead to major projects

Question:
How crazy is it to think of rewiring the whole truck?

The answer is that it depends upon your skill set and what you want to end up with. It sounds like you are looking for a modified harness that you can not buy off the shelf. To do it yourself you should be able to both read and understand wiring diagrams. You need to understand how relay circuits work and how to redraw diagrams to include them in the circuit.

If you are weak in understanding basic automotive electrics you will need to find a adult class or JC class covering this. If you are going to do a decent job that will last decades it really helps develop this skill before attempting the work.

So far I've rewired 5 Series trucks from scratch (the front harness from scratch, rear harnesses if needed from premade rear subharnesses), including my own truck which has likely one of the more complicated harnesses on a Series truck.

I have a few suggestions & comments:

1. know what you are doing before you do it

2. document your wiring harness. It helps to know where wires go if you have to change or repair something in the future. This should include a drawing of your fuse block, the size of each fuse and a listing of what each fuse connects to.

3. colour code your wiring so you can tell one wire from another. I didn't think of that on the very first car I built a harness for (an old Ford). I got a roll of this really good white wire and did the whole car with it. I had a horrible time figuring out what went where.

The British automotive industry has an insulation colour code for for wires used for specific uses. At a glance you can tell what a specific wire in a bundle is used for and where it goes. I suggest using the British standard for your wiring. It means buying a lot of odd lengths of different wires in different sizes, but if you keep your truck a few decades you will come to really appreciate your efforts as will the next owners.

4.If you have a generator, convert to an alternator. The Delco 3 wire alternators are the standard type used for a conversion.The Delco 10-SI and 12-SI series are the most common used.

Pangolin 4X4 makes a set of brackets what will mount these alternators at the top of the engine above wading depth. These brackets make the alternator mounting a snap and is more than worth the price.

I have a web page that goes over the basics of converting to these Delco alternators.

Oh and it is a good idea to use a voltmeter instead of an AMP meter to monitor your charging system.

5. I didn't see the year of the Land Rover mentioned. The ones that came from the factory with positive earth have a combination headlamp and ignition switch. These ignition switches are only good for about 12-13 AMPs of draw and are very expensive to replace. When I rewire trucks that will carry higher switched 12V current I add a relay. When I'm done all the ignition switch does is switch on and off the main power relay. That relay in turns handles the current flow for all the switched 12V.

6. I had been using the same wire routing behind the instrument panel that the factory used resulting in the same mess. On the last truck I rewired I added a barrier strip to the inside of the bulkhead, centered behind the panel and used the barrier strip for all the inside connections. It cleaned up the area very nicely and made everything much easier.

7. connectors. Most electrical problems in old Land Rovers are caused by dirty corroded connections. At first I used the standard Lucas bullet connectors but during the last decade or two I have been having problems inserting them into new barrels. So I have switched over to the crimp connectors commonly used in the US. Which ever you decide to use, invest in a proper crimping tool. The cheap pliers style found in every hardware store does not make a proper reliable crimp. There crimps will become a source for future electrical circuit problems. Invest in the proper crimp tool for what ever type of connected you decide to use. The cost closer to $75 or so but they are well worth the investment if you want to have an electrical system that is trouble free. And never use a spade connector where you can fit a ring connector.

There will be places where you will need to make solder connections. Invest in a good solder gun, and a heat gun for shrink tubing. Use shrink tubing instead of electrical take whenever possible.

8. Relays - Relays out of wrecking yard cars are usually better and more splash resistant than what you will find in an auto parts store blister pack. You are more apt to find discrete relays in 1980s and early 1990s cars. I suggest haunting wrecking yards for relays before hitting the auto parts store. The ones in the auto parts stores almost never have any moisture protection.

My favorites are found in late '80's Cadillacs on the front left inner wing panel. There is a group of 3 Bosh relays that have potted sockets and triple water seals between the relay and socket I have been using them for headlamp relays, horn and electric fan relays.

9. Don't get overwhelmed - a car electrical harness is nothing but a whole bunch of individual wiring circuits. Focus on doing one circuit at a time and testing that circuit when it is built. It is really simple when you do it that way. Build you r harness one circuit at a time then button up your harness after each circuit is wired and tested.

Basically, a brown wire from the battery to one side of the ignition switch. A white wire from the other pole of the ignition switch to the coil. A wire from the other low tension connector on the coil to the side of the distributor and you have spark. A wire from the battery to the relay switch and from the relay switch to the starter motor. A ground strap from one of the starter motor mounting bolts to the frame on a pre '67 and you have a functional starter circuit so you can start and run the engine. On the later ones you add a wire from the switched side of the ignition switch to the electrical started relay to make it happen.

It is all that simple if you take it one circuit at a time. You just need to be able to understand what each wire does, how to read it on a schematic and how to make proper crimp or solder connections.

-----

Anyway these are just suggestions if you plan to create your own wire harness. Please feel free to use or ignore any you wish.

[rbbailey]

Thanks, Teriann,

Lots of good info. I'm confident enough to do the work, I'm just not sure I WANT to go through with it because it will take me a long time...

I am thinking I might build my accessories wiring harness in such a way that if/when I ever do have problems with the original, I can leave it in place while gutting and rebuilding the original.

A couple of things:

1. How do I figure out what type of Delco the truck currently has? (It is mounted high on the driver's side of the engine -- don't know if it is one of Ike's brackets or not, but it was that way when I bought it in 1999.)
2. Yes, I hate the ammeter. It makes no sense to me, and I believe that is because it is a neg earth alternator now, not the original generator -- right? Any suggestions on getting a volt meter?