Custom Wiring Questions for a 62 Morris Mini –
I’m wondering if I need any more or any different parts.
I am doing a custom wiring using a Speedway Motors simple 12 circuit harness for a 62 Morris Mini because I didn’t want to return to a 2 or 4 fuse wiring harness. I suppose I should say sorry for making this decision, but it is a decision never-the-less that I’ve made, and have progressed with the wiring reasonably well, I think, up to the question(s) in this document. The challenge has been that the car was put together from parts, and may not be an exact 62 Morris Special as indicated by the information on the car body. The wiring was 50 years old, of course, and terribly deteriorated, to include painted over, and faded beyond recognition. I’ve used a several wiring diagrams to make judgments about the original wiring of the car. I’ve gotten to the point involving the wiring of the combination Starter Switch/Solenoid (which has confused me some ) to the starter and to the LRA100 Alternator GXE8211. I’ve attached (linked) a pdf document that illustrates the wiring as I have presently planned it, and am wondering if I’m on the right path, or am I going to burn everything up? The car was positive ground, and I’m now going to have it negative ground. The new alternator is used in place of the original positive ground generator, the positive ground radio is not being converted and a radio is not presently planned. Ammeter is not being used. Other original gauges and sending units will be used.
First, I’ll ask a brief version of my question on this page. Please see the link for more information where I've tried to provide some diagrams and detailed explanations of the question as it applies to my custom wiring.
The question is : What is the purpose of each of the spades on the LRA 100 Alternator GXE8211?
Small top spade: alternator excitor?
Middle large spade: power to alternator?
Bottom large spade: ????

Again, in the link pages, I have identified the detail questions with the following format: Q?? So we can discuss each question as may be needed. T

 

Yep, been there, done that. I replaced my Lucas wiring harness after the previous owner let out all of the smoke. I replaced it with a Painless Wiring 12 circuit hot rod harness, probably nearly exactly what you have. I found it to be very straight forward. The two problem areas I had were (1) replacing the electrical switch component of the ignition tumbler / switch, and (2) finding a good place for the fuse block. Everything else went very well.

I found the wiring diagrams in my MIni factory service manual very helpful.

I don't know about your alternator specifically, but if I remember correctly, my Lucas alternator had three wires: one used as an exciter (power to the alternator), one to the instrument cluster (to indicate charge or charge failure) and one to charge the battery (the big fat wire). I don't care about the charge indicator, so I only connected the exciter and charge wires.

I had a fair number of circuits unused in my harness ... things like radio and electric engine fan. The only new circuit that I've had to add was for an electric fuel pump. For some reason the 12 circuit harness doesn't have a switched 12v circuit for fuel pump.

Good luck with your project. I learned a neat trick from the Painless instructions. After everything is wired up, power the harness off of a 12v auto battery charger set to 10amp so if you have a short somewhere your new wiring won't go up in flames.

If you care, pictures of my swap are here:
Jeff

 

Regarding your PDF:

You should try to track down a wiring harness from an alternator mini and trace the charging system wires to confirm which wires go where. I did that and it worked out fine.

Q1: I believe it is the exciter wire, yes.

Q2: same as Q5 - both for the same purpose - to charge the battery. You can confirm this by grounding the alternator body, powering the exciter wire with 12v, and spinning the alternator. You should see a voltage induced between the charge wire(s) and ground.

Q3: I wired mine with a fused circuit from the alternator charge spades to the positive terminal of the starter solenoid. This is effectively battery positive. I opted for a 70 amp maxi fuse (huge physical size) inline in this circuit to prevent the alternator from melting the wire if the internal regulator fails.

Q5: I think there are two spades so that two smaller wires could be run to charge the battery instead of one big fat one. IIRC the two large spades are shorted together (as in same circuit) at the alternator.

Cheers,
Jeff

 

Your answers and advice are valued. Glad to find someone with a similar idea. I trust the Painless and Speedway harnesses are similar. I've got limited time to think about the project and to work on the project, so I'll get started. I'll check your pics as soon as possible.

 

Jeff, I contacted Speedway tech on the questions I have. It is difficult for them to be specific because they do not deal with Lucas Alternators. I got some direction however, and will post more as soon as I can get it down on paper. The biggest challenge for me, is to sort out what connects to this specific Alternator on each Spade. The thoughts after my call to Speedway is that the top (small) spade is only for an indicator light in the dash, and there doesn't appear to be any such wire in this small harness. The middle (large) spade thought now is that it is likely for the alternator excitor. And the bottom (large) spade is to send power back to the battery. How should this bottom (large) spade be wired back to the battery? Jeff, how is yours wired with the Painless harness, if your alternator has three connectors/posts?

 

And let me see if someone else can also help with the Spade question on this alternator: Lucas LRA100 Alternator GXE8211. My question is what are the purposes for the three spades:
1. For the small (top) spade? indicator?
2. For the large (middle) spade? excitor?
3. For the large (bottom) spade? power back to battery?

 

off the wall question / suggestion

when I blew the alternator in my 79 I had many suggest just buying the alt' from a current US car that appears to be a direct fit and HAS documentation {satern}

or ... any GOOD alternator with a good connection to your harness?

Physical mounting to the engine is NOT an issue is it? Can you simplify the electrical side for $60 bucks at the parts store?

 

You ready? This took me a while to write ...

Although it may not be much help for this exact problem, check out this thread, post #31 from myself. It has an attachment called mini_wiring.pdf that is a rough reference I created when I was installing my harness. I am absolutely certain that I didn't hook up the IGN instrument cluster lamp. It shows a ? on the exciter connection because I could only speculate that that's what it was.

So, just for you, I opened up the bonnet and dug around the wiring. It looks like I have three wires going to the alternator; two red ~ 10 gauge and 1 write 14 gauge, but only the two red wires are connected. For some reason I purposely didn't connect the white wire because I have shrink tubing covering the end. My Painless manual says white wire 914 (14 gauge) is alternator exciter and red wire 915 (10 gauge) is Alternator Bat+, As best I can tell (without pulling the harness apart) the two red wires both effectively connect straight to BAT+. Hmm, looks like my Lucas alternator doesn't have circuit 914 connected, and I've been running like that since 2008. Perhaps connecting the bat+ to the alternator has excited the alternator all of the time instead of only when the key is on. Althhough a week ago I measured the parasitic loss across my battery with the key off and I got 0 mA.

Ok back to your question ...

Edit: there are three spades on my alternator (looks like yours). The innermost (from the center of the alternator) and center spades are (I believe) connected to the starter solenoid bat+ post via a 70 amp maxi fuse. The outermost spade is not connected to anything.

For what it's worth, I think I didn't connect the wiring harness' exciter wire because I was originally going to swap in a GM 1-wire alternator from a 70's GM vehicle that doesn't need it . I bought one for a Nova but never installed it. It's sitting on my shelf waiting for the Lucas alternator to become smoke-free.

Hope it helps,
Jeff

 

Perhaps the wire that I didn't connect is for the instrument cluster idiot light. Just a thought.

 

I don't know the answer with any authority to the question about using a non-mini alternator. I have read some forums somewhere about the subject. My recollection about what I've read is that this option is certainly possible, but there are better options than others. You might try searching forums on MiniMania, http://miniaddicts.co.uk/Home.html, and miniworld.com. Hope that helps you in a positive direction.

 

Jeff thanks for you two posts. I've looked up the wiring document you site. I've been studying some new info most of the evening. (not at home to do any actual work on the car) and by the time I got to your posts, it is just to darn late. I will consider your thoughts, and I really appreciate you looking under the hood. There aren't any alternator Classic Minis in my town (that I know of), to look at under a hood. And unfortunately my cars have all been generator based. I did, today, get some authoritative and highly reliable information about the alternator spades: small (top) = alternator excitor and also indicator light; middle large and bottom large = power back to battery. I've enjoyed trying to understand this area of automotive wiring, but I find it gets confusing very easily, especially when trying to correlate the classic mini with the Speedway Motors harness. Again, thanks for your efforts. I'll think more about your wiring descriptions, and will probably work up a couple more questions. I think it is entirely possible to get a car to run with some variations in the circuits, and the key is to make it as safe and reliable as possible. Your record since 2008 sound pretty good!

 

Thanks for this detail, after lifting the bonnet! That is fantastic. I'll study and compare to more information learned today. From a Mini authority: the lucas alternator top "small spade" is for alternator excitor and also indicator light in dash; the two larger spades are for power back to battery.

 

I've replied a couple times to your comments. But they aren't showing up. Still trying to learn the forum methods. Thanks for looking under the bonnet! Wow! Your comments again are of great help, as I digest them. And this is the third time noting this: from an authoritative classic mini source my alternator spades serve these purposes: top (small) spade = alternator excitor and also indicator light; the middle and bottom large spades = power back to battery.
Oh, and FYI, I have looked at the pdf document in the other thread, it will take some more study, but looks great. And I had seen your post sometime back regarding your wiring install photos, which has been of great value as well. Thanks for your efforts.
Thanks again,
Russ

 

Jeff, A couple/three more questions/comments: 1. What was your decision regarding the ignition switch, that you ended up using? Do you remember, without having to do a lot of research? 2. FYI, I added a Fuel Pump Relay from Painless, and the Speedway harness fuse box already has a fan relay and a horn relay built in. (omiting the Fuel Pump Relay makes the harness an economy model I suppose. 3. The use of the MaxiFuse 70amp causes me to wonder why that amperage, my alternator is lower amperage than that, but if the internal regulator failed would it put out more amps? Thus the need for the 70amp. It sounds like a good idea to use the MaxiFuse, would there be any reasons not to use one?

 

1) Ignition switch - not sure what you mean about what my decision was. Being a MKIII Mini, the steering column and ignition switch parts are no longer available. I found that a 1974 MG Midget ignition switch had interchangeable parts with the Mini and I swapped the electrical components over (pictures in my photo gallery). My ignition switch was cooked where the 12v switched wire exited the switch.

3) The value, from what I've read, is that if the internal regulator fails the alternator may generate significantly larger voltage than the 12v expected. More voltage means more current, so the Maxifuse will potentially mitigate that failure. Why wouldn't you use one? It's yet another thing to wire up and install and it's another thing to buy (my Painless harness came with one).

 

I forgot about the photos you had displayed about the switch, thanks for your reply to help me remember! I've been siding my house, so when that project is done, I'll be able to put some of this helpful discussion to use on the car project.

 

Just and update. Still working on the project, never have a lot of time to work on the harness project. But I got the engine running yesterday for a test start!. Now working on the following questions:
Q1: Turn signal switch on steering column has a light at the end. It blinks when I use the switch to both left and right. The light is always at the end is always on after my the wiring harness job. The question is should the light always be on? If not, what is the problem?

Q2: Fuel gauge isn’t working. This is after a the wiring harness job. To do the harness work I totally removed the gas tank, and have reinstalled it. I tried to be careful but I did hear the sending unit in the tank bang against the tank a couple times while maneuvering it during reinstall. I have watched the gauge with both the engine running and with just the ignition switch on to power lights. Given these facts what should I consider to get the gauge to work?

 

I can't say since my '73 Mini has a MKIII turn signal stalk. Perhaps someone else here with an older Mini can advise ...

The fuel gauge circuit is all based off of resistance. On my tank there are two electrical contacts to which the harness connects; one is ground and one is signal. Disconnect the harness from the tank and get a resistance reading from the sender. 0=bad, infinity=bad, small values (<200) mean the sender is probably good. That's the easiest way IMO. If the sender resistance values seem reasonable, reconnect the harness and check the resistance at the other (gauge) end. You should [obviously] get the same reading. If not, the harness is damaged. I assume the other gauges work fine.

Good luck,
Jeff

 

Thanks again Jeff, the problem was determined, to be "no power to the gauge".

I'm still wondering about "Q1: above... The question is should the light always be on, on the turn signal switch? If not, what is the problem?" Hopefully someone with a similar turn signal switch on the steering column can tell me if that is normal to have the light always on.