[Mgs] Was: coil; now wiring issues

[Max Heim]

I thought I should start a new thread rather than taking over the 1974 coil topic.

I wasn’t pointing fingers, just reporting a fact for general reference. I found another discrepancy today, although it is unclear whether the fault is in the wiring diagram or the part. The colors shown for the turn signal indicator wires are reversed, compared to the wires built into the turn signal switch. This was a Moss replacement switch, made in China, so it is very likely that it was just manufactured incorrectly. Anyway, it is easy enough to just switch the lamp positions.

I am having a persistent problem with the right side lamps, however. The indicator flashes, but I can’t get anything out of the front or rear lamps.  I can’t even get the test lamp to flash with the probe inserted in the very first junction, or even on the contact in the switch itself. This is rather baffling — all it could be is a discontinuity inside the copper rivet, it seems to me. This switch was functioning on the other car, last year, but I can’t say I am very impressed with its quality of construction. Unless someone has a better suggestion, I think I am going to order another switch.

I still don’t have the fuel pump working. It has 12v at the terminal, and not on the body. I am thinking I will have to take it apart and look at the points. I got distracted with the dash wiring.

As for the other faults, well, I discovered that none of the dash switches were actually functional. I had pulled them from the project car and cleaned them, but that was a few years back. Apparently I had never subjected them to testing. So I just pulled the full set off the runner. Now I have headlamps, tail lamps, running lights, map light, wipers and heater fan. Couldn’t really see if I had instrument lamps due to sun glare. Didn’t think to test high beams. Wasn’t ready to test reverse lamps or OD operation. Didn’t have an assistant to check brake lights.

One issue with carrying over the headlight switch: this late 1966 dash has it position-swapped with the washer pump button compared to the other car. So fitting the toggle switch in place of the pull knob means it actually rests against the crash pad in the off position. I can’t just exchange it with the pump because the pump threaded section doesn’t have a flat. So I suppose I will need to order a new pull switch. BTW I disassembled the old one to see if it could be repaired and it was a disaster inside —several broken springs and a broken lever. I think it’s a goner.

Oh, I did have the tach wire on the wrong side of the coil. 

Anyway, learned some things, made some progress.

Sent from my iPad

> On Jul 28, 2018, at 2:50 PM, Barney Gaylord <barneymg at mgaguru.com> wrote:
> 
> Yes, it is an omission.  There is no error or omission on my web site, because I don't have any MGB wiring digrams on my MGA web site (so I didn't do it).  I am also webmaster for Chicagoland MG Club, and that web site does have MGB wiring diagrams, more than 30 of them here: http://chicagolandmgclub.com/techtips/mgb/mgb_wd.html
> 
> I didn't draw those diagrams.  They are in PDF format, and I don't have the capability to easily  edit the documents.  And of course I couldn't possibly correct every MGB wiring diagram that has ever been published or printed.  Accept them for what they are, unless you want to re-draw them for new publication.  
> 
> All 1968 or later MGB, and any earlier car that has been converted to altermator, will be negative earth.  Some earlier generator cars may also be converted to negtive earth.  Look at the battery to see which post is grounded to the chassis.  Coil terminal with that polarity designaton should be connected to the distributor.
> 
> On a side note, if you get it wrong and swap the coil terminals, it wil still run pretty much the same.  It only means the spark will jump opposite direction across the plug gap. There is some "speculation" about whether or not this may slightly affect strength of the spark or life of the plugs, but if it has any effect on the way the engine runs, there may be something else wrong with your ignition system.
> 
> Barney
> 
> 
> At 07:35 PM 7/27/2018 -0700, Max Heim wrote:
>> Right. But if you have both leads disconnected, the diagram doesn’t tell you which goes to which. That seems to be an omission.
>> 
>> --
>> Max Heim
>> mvheim at sonic.net
> 
> 
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