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Discussion Starter #21
Hi Rod,


So not an original harness, which is what I based my previous advice on. Given the other differences you've mentioned, an educated guess says it's Wassell "Genuine :LOL: Lucas" ...


Are you sure the tracer's definitely Green and not a shade of Blue? Brown/Blue was the 'original Lucas' colour code for the wire attached to the battery "not-ground" terminal since some time in the 1950's; any bike not fitted with an Ammeter, Brown/Blue continued to the ignition switch.

'Original Lucas' did not use the same wire colour/s for entirely-different connections. Specifically Brown/Green was always the 'original Lucas' colour code for wires to pilot bulb and rear bulb tail filament - as you've noted, there are two Brown/Green wires attached to Lighting switch terminal #7; if you wish to be sure, use an Ohmmeter or the Ohms function of a multi-meter to test continuity between Lighting switch terminal #7 and those two bulbs.

Otoh, if you test continuity from the ignition switch, you'll likely find one Brown/whatever wire goes to the rectifier and battery -ve, the other Brown/whatever wire goes to the Zener.


Original '78 T140E-specific harness didn't have either Brown/White or Brown/Blue from ignition switch to Lighting switch; these are Lucas colour codes specifically for unswitched connection from/to the battery ('78 T140V has Brown/White).

At the Lighting switch, you should connect the Brown/Blue wire from the ignition switch to terminal #4 specifically (not #3).


This specifically depends on the ignition switch connection of the Lighting switch Brown/Blue wire in your bike's harness. As in my previous post, the ignition switch has either three or four male spade terminals:-

. if three, you can see two terminals are connected together and one isn't;

. if four, you can see they're connected together in two pairs;

. risking stating the obvious, terminals not connected together on the outside of the switch, are connected together inside the switch just when the switch is 'on'.


White is the Lucas colour code for wires switched by the ignition switch. Otoh, as I've written above, one of the "Double Brown/whatever" wires is unswitched from battery -ve.

So, with "Double white" on one terminal and "Double Brown/whatever" on another terminal not visibly-connected to the White wires' terminal, the White wires are energised only when the switch is 'on' (or the switch is faulty).

So, if you connect the Lighting switch (Brown/Blue?) wire to the ignition switch terminal visibly-connected to the White wires' terminal, the lights will be switched on and off with the ignition. (y)


The reason Meriden used a 31788 (or 35710) Lighting Switch on the '78 T140E is specifically within those switches terminals/positions #1, #3, #5 and #7 are connected together internally.

So, on an original '78 T140E harness, if a White wire switched by the ignition switch was then connected to Lighting switch terminal #1, and terminal #7 has the Brown/Green wires specifically to pilot bulb and tail filament, those two bulbs would be illuminated all the time the ignition is switched on, to comply with the 1978 FMVSS. (y)


Blue supplies the headlamp dipswitch on the handlebars. One Lighting switch position connects terminal #7 to terminal #8. So the headlamp will be on in one Lighting switch position and off in the other two.


Not if you carefully read and follow all my advice. ;)

Hth.

Regards,
You are correct sir,.... my mistake. The wires from the ignition switch are indeed double white and double BROWN and BLUE not GREEN as i stated earlier. My apologies for the misinformation. Your humble friend,....R.T.
 

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Okie Dokie no problem

As an old anal person I am going to ask a couple of unanswered questions and make a couple of statements.

Your ignition switch has only on/off positions. While the switch has four connection points for female 1/4" spade terminals there are really only two connections to the switch. The male side wire connections are really two U shaped items with two connection points each. The U shaped bits are riveted to the switch base. Correct?

The new loom has push together plastic connectors like your original loom had and not the old style bullet connecters Correct?

Did you leave the diode assembly (located between the ignition switch and headlamp) in place? The complete assembly is Triumph Part # 60-7079 while the Diode only is Triumph # 60-7082 (LUCA$ #83225A) If you are not familiar with this part Google TRIUMPH 60-7079 and Klempf's will come up. He has a nice picture of the diode assembly.

Your parts book are you using both Part # 99-7003 (MARCH 1978) and the 1978 T140E supplement Part # TMA-9 (JUNE 1978)?

Do you still have the original switch you replaced? If so what is the number stamped on it.

Yes there is a reason for every comment/question above


K ?
 

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Hi Rod,

The wires from the ignition switch are indeed double white and double BROWN and BLUE not GREEN as i stated earlier.
:) No worries; it's a replacement harness; even when it isn't, colours (not to mention eyesight :rolleyes:) can have faded in over forty years.

The original may have been 34419 as listed in the original 78' parts book i have used for years.
Just to be clear:-

. The original - as in when the bike was brand-new - Lighting switch could never have been a 34419, because that switch cannot be connected to keep the lights on at the same time as the ignition, to comply with the 1978 FMVSS requirement.

. It isn't impossible that the original (as in when the bike was brand-new) 31788 switch might have been replaced later with a 34419. That could be a reason you found a Brown/Blue wire from the ignition switch to connect to the Lighting switch - whoever fitted the possible 34419 was attempting to follow the standard Lucas colour code for an unswitched wire from the battery?

34419 as listed in the original 78' parts book
Mmmm ... but that's a T140V parts book, not a T140E parts book ... :) The '78 T140E was only produced in the 1978 calendar year and was only sent to the US; at the same time, Meriden continued to produce the '78 T140V for everywhere else in the world.

Meriden never produced a '78 T140E parts book. If you look in the link in one of my earlier posts, you'll see:-

. It's specifically titled "SUPPLEMENT", meaning it was intended to be read in conjunction with the Meriden '78 parts book; i.e. parts not specifically listed in the supplement were as in the parts book; otoh, supplement "Page Fourteen" specifically lists 31788 replaces 34419.

. The supplement was produced by TMA, the-then US Triumph importer.

Hth.

Regards,
 

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Stuart

As I stated in my last post every question has a reason. I have found a few anomalies I am trying to resolve.

Regarding the parts book there are multiple publication dates for the 1978 T140V/TR7RV.
The March 1978 includes parts for the 1977 Jubilee, while another one lists shock absorber bushings as complete headlamp assembly.

The US 1978 T140E book was printed by TMA (Triumph Motorcycles America) Interesting Meridian found no reason to publish a parts book for a machine that they built. But then I have never been able to get a Parts Book or Part Number for a Parts Book for a 1974 T120V also I have never see a parts book for a UK T140D.

Regarding the lighting switch used in the T140E headlamp. It is my belief the 1978 US T140E came with part LUCA$ #31788. Note on page 14 of the parts Supplement TMA-9 it states switch 34419 was replaced by 31788. Also on the same page it is stated Diode Assembly is used between the headlamp switch (31788) and the ignition switch. I would also point out that T140V from 1973-1978 used the 34419 switch.

Bottom Line my opinion if switch 31788 is used without the Diode pack Rod will have the problems described

K ? :sleep:
 

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Hi K, :)

Hope you're all still well? All basically OK here, everyone else suffering with a lergy (but not The Lergy :eek:) my brother-in-law kindly gave me, I'm now fine ... :ROFLMAO:

It is my belief the 1978 US T140E came with part LUCA$ #31788.
(y) I've also seen 35710 but, as I posted for Rod earlier, the two switches function identically.

if switch 31788 is used without the Diode pack Rod will have the problems described
Ime, no, and no reason it should. You might remember a previous discussion, when I posted I'd never seen the diode(s) and White wires? Absent seeing 'em connected, I've never been able to work out how they were connected, or why?

As I posted earlier in this thread, 31788 and 35710 were used interchangeably from '68 (when the toggle switch replaced the 88SA rotary switch) 'til replaced by 34419 on '71 OIF and triples, the switches continued in use on the T100 'til it was killed off by the sit-in. :( Fwiw, my T100 and T150 are '69 and '70, one has a 31788, the other a 35710.

In the same period, all bar the '71 and '72 OIF and triples used the on-off ignition switch. So the on-off ignition switch feeding a 31788 or 35710 without diodes worked for six years on tens (hundreds?) of thousands of Triumphs and BSA's (if you count '68-'70 Notruns and Royal Oilfields, definitely hundreds of thousands). :)

I appreciate the ignition switch on all the above fed Lighting switch terminal #4 whereas it's terminal #1 on a '78 T140E's original switch. However, if you look at '68-'74 wiring diagrams with the on-off ignition switch, they include the 31788/35710 internal connection diagrams, and you can see feeding those Lighting switches at terminal #4 or terminal #1 only makes a difference to whether you can turn off the lights completely (feed terminal #4, you can; feed terminal #1, you can't, only with the ignition switch).

The operative word in the last para is "or". First-hand :oops: experience suggests Rod connected up his 31788 switch the same as shown in the ('71-)'78 wiring diagram, which all show a 34419 switch ... ? The crucial difference between the two types is 34419 doesn't have terminals/positions #1, #3, #5 and #7 connected together internally, which is why you can connect input Brown/White (or Brown/Blue) to terminal #3 and input White to terminal #7. Otoh, looking at a '68-'74 wiring diagram with 31788/35710 internal connections, 'make' the two input connections and compare the results to the symptoms Rod described in his first post to this thread ... :whistle:

The US 1978 T140E book was printed by TMA (Triumph Motorcycles America) Interesting Meridian found no reason to publish a parts book for a machine that they built.
Mmmm ... could've been the time ... bear in mind this was around when Meriden got loose from its previous marketing deal with NVT?

Hth.

Regards,
 

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Discussion Starter #26
Okie Dokie no problem

As an old anal person I am going to ask a couple of unanswered questions and make a couple of statements.

Your ignition switch has only on/off positions. While the switch has four connection points for female 1/4" spade terminals there are really only two connections to the switch. The male side wire connections are really two U shaped items with two connection points each. The U shaped bits are riveted to the switch base. Correct?

The new loom has push together plastic connectors like your original loom had and not the old style bullet connecters Correct?

Did you leave the diode assembly (located between the ignition switch and headlamp) in place? The complete assembly is Triumph Part # 60-7079 while the Diode only is Triumph # 60-7082 (LUCA$ #83225A) If you are not familiar with this part Google TRIUMPH 60-7079 and Klempf's will come up. He has a nice picture of the diode assembly.

Your parts book are you using both Part # 99-7003 (MARCH 1978) and the 1978 T140E supplement Part # TMA-9 (JUNE 1978)?

Do you still have the original switch you replaced? If so what is the number stamped on it.

Yes there is a reason for every comment/question above


K
Yes, only on/off at ignition switch.

Can't recall harness connectors, but don't believe they had the plastic push connectors.

As to the Diode,..... What diode?
I googled it as you said. I've never seen one before as I can recall.

And yes the parts book is as you've stated.

Regards,.... R. T.


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Rod
Do you still have the old wiring harness?

Stuart
Thank you for your concern. Wife is in Florida tending to her brother he is at home in hospice. Had a friend pass in February from similar problem. Also been trying to write obits for this site for two people since January . I've been on pretty much quarantine for 3 1/2 weeks. With all the health problems if I catch it it will be bye bye K.
As far as the switches they may be similar but not the same Spending some time looking into this and comparing diagrams. While there were two part numbers for the harness on T140s between 73 & 78 they were the same except for the connectors and the headlight bulb holder starting in 1977.
It doesn't surprise me you have never seen the diode . It would have only been used on US & Canadian bikes after 1/01/78. I remember seeing one in the Parts Bin at the shop where I worked. I do not know if T140Vs or TR7RV bullt after 1/01/78 were imported into Canada. As an aside the Canadian specification bikes were at times different from the US Spec and not the same as the UK/Gereral Export machines.
I will try to stay awake tonight ? long enough to check somemore

K?
.
 

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Hi K,

While there were two part numbers for the harness on T140s between 73 & 78 they were the same except for the connectors and the headlight bulb holder starting in 1977.
will try to stay awake tonight ? long enough to check somemore
I can help with a few things:-

. The two different main harness part numbers aren't the (BPF and P45t (410 and 411)) headlight bulb-holders; bear in mind, while the US and left-hand drive countries (GB, Oz, NZ, etc.) got the BPF headlamp/bulb/holder 'til sometime in '77, certainly bikes going to Europe got the P45t bulb (410 for most European countries, yellow-tinted 411 for France) for years before. The bulb holders had short wires with bullet terminals, the appropriate bulb holder for a given destination was attached to the main harness with snap connectors, the main harness was the same irrespective.

. The two different main harness part numbers are pre-'76 and '76-'78 (the pre-'76 54961593 shown in the February 1976-issued parts book is one of the misprints in that book). This change is because the handlebar switch clusters had to change to give the on/off kill switch to comply with the 1975 FMVSS, '76-'78 twins have the same switch clusters as the T160, which had the plastic-plug-pin-socket connectors (aka 'AMP connectors') whereas the different pre-'76 switch clusters connected with individual bullets and snap connectors.

. One thing the '78 T140E supplement doesn't list is a different main harness from the ('76-)'78 T140V?

doesn't surprise me you have never seen the diode . It would have only been used on US & Canadian bikes after 1/01/78.
Sorry, I should've been clearer - I meant I never saw them on '78 T140E's that turned up in GB from the mid-1980's onwards.

Background - The British market was very short of second-hand bikes from about the mid-1980's to the early-1990's (because the late-1970's industrial unrest had depressed the British market for new bikes then, which resulted in the later shortage). Several bright sparks hit on the idea of importing used bikes from the US, mainly Japanese, but a few people also noticed how cheap, say, late 1960's Britbikes were in the US compared to what they generally sold for in GB. :whistle:

People who imported or bought US-used Britbikes generally expected more problems than from US-used Japanese bikes, if only because the Britbikes were older and had survived the same periods of limited spares and being used as cheap transport as similar never-exported Britbikes. So the first few '78 T140E's that appeared with apparently-non-standard headlamp switches and wiring were assumed to be DPO mods; it was only when the knowledge came over too (absent anything bar the parts book supplement) that people realised it was a US-only model GB'd never seen.

So, as I say, never having seen the diode connected and having the same ignition switch and lighting switches without any diodes on two of my Triumphs, I've never been able to figure out what the diode might've been for or where it might've fitted. :unsure:

Hth.

Regards,
 

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Good Evening Stuart

The different harness numbers was caused by the use of the AMP connectors (good a term as any) AND bulb holder for the 410 bulb and it's variants. The later was introduced with the 77 model year. I would be interested in comments from owners of original 76/77 T140's and TR7's what headlamp bulb their bikes use.

You are very correct the 78 T140E US supplement doesn't list a different harness from the 77-78 T140V/TR7RV. Yet it does list a different light switch and the Diode assembly.
That tells me the 1978 TR7RV/T140V&E used the same harness. The ONLY difference was the switch and Diode assembly. Maybe there is an owner of an unmolested US 78 T140E out here that can take a look at the position of the Diode on his bike and advise. It would be between the ignition switch and the headlight toggle switch.

I submit if Rod uses T140E switch without the diode he will have the problems he has described. If he were to change to the 73/78 switch his problems would go away. But what I know? Over the years here and the other place I have been told I know jackshift. One of the reasons I have limited my posts lately. Will shut mouth at this point on that.

As far as never seeing a diode assembly on a repat bike that doesn't really surprise me.
Many of their former owners were not qualified to plug in a toaster. Harsh? Nope. I worked the parts counter. One guy said the W headlamp clips I sold him were wrong. The only clips Lucas( 504665 ) that were used in the 1960/70's. Or I sold another guy the wrong steering head bearings had nothing to do with the fact he was building a chopper with an aftermarket springer. One of my favorites was the gentleman that was buying his new carbs from the other guy because he was going to airflow them.?? Gotta admit the other parts guy was a creative seller. never figured out how he didn't wind up in the Chicago River. From selling parts to guys for over forty years I have learned a lot.

As far as the background ... In the 80/90's we had people that would take any used machine off our hands and were looking at every advert in the papers.. Containers went to the UK, Australia, Poland, Europe.

Nothing against Rod but I have asked some very specific questions and not gotten a direct answer. Not my scooter that has a problem. Outta here ?
 

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Discussion Starter #30
K....
I'am sorry if I've failed to answer the specific questions that you have asked. I seem to have sorted the problem out. I now have oil pressure light and tail light with ignition switched on, and (fire at points).
The toggle switch (31788) activates the pilot lamp (first position) and main beam (second position) with (NO fire at the POINTS) , key NOT switched on. High beam also works when switched from handlebar switchgear.
I have disconnected the white wire from the toggle switch altogether.
I will repost with switch terminal numbers I've connected.
While neither a mechanic nor an electrician (God bless J. Lucas) I've been the sole caregiver to this machine for 42 years.
I'll now plug in my toaster and go for a ride...


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Hi K,

The different harness numbers was caused by the use of the AMP connectors (good a term as any) AND bulb holder for the 410 bulb and it's variants. The later was introduced with the 77 model year.
Uh-uh. The 410 bulb, plug and lens/reflector were introduced to the US during the 77 model year; as I've posted before, they were fitted to bikes destined for European countries for several years before '77:-

. Afaict, they were first used in '72. Pre-'72, the yellow-tinted bulb for France is still one number above but it's one number above the usual BPF one - e.g. the usual '71 BPF bulb is 370, the '71 French yellow-tinted one is 371.

. Possibly you don't have access to European parts books; however, you do have access to the T160 book (e.g. Vintage Bike Magazine » Parts Books) so late 1974 - on page 89, the 370 bulb, plug and lens/reflector are listed as "N. America & U.K.", the 410 bulb, plug and necessary lens/reflector are listed as "Europe", the French yellow-tinted 411 bulb is listed on page 91, that page titled, "SPECIAL ITEMS - EUROPE ONLY".

. The French yellow-tinted 411 bulb is also listed by its Triumph 60-3671 part # on page 77 of the '74 T150 Series 2 (all Small Heath-built) parts book.

. There are at least two different versions of the '76/'77 parts book both showing as "Published August 1976":-

.. "T140 1976-77 99-2257R" on the Vintage Bike magazine site lists only the 370 bulb, plug and lens/reflector, as "UK - USA - Canada";

.. however, the version on the British Only site and on the Kim The CD Man CD - printed in a different font - additionally lists the 410 and 411 bulbs, plug and necessary lens/reflector as "Europe" (and with Norton part numbers).

Both the BPF bulb holder and 410/411 bulb plug have only short wires attached, with bullet terminals; if nothing else, the Blue/White headlamp main-beam wire only has to go a short distance into the shell before it connects with the idiot lamp wire and the dipswitch wire at a 'double' snap connector. Nevertheless, the Blue/Red headlamp main-beam wire and 410/411 plug Red wire also connect by bullet terminals into snap connectors.

The bulb holder/plug was separate from the main harness - all of the above parts books list part numbers for the BPF bulb holder and 410/411 plug. Otoh, none of the above parts books list a different main wiring harness for "Europe" so I cannot see how the different bulb holder/plug can have been a reason for a different main harness part number.

bulb holder for the 410 bulb and it's variants. The later was introduced with the 77 model year.
The positive on/off kill switch was required on '76 twins for the US that started building in August 1975. Therefore the new right-hand handlebar switch cluster and therefore the new left-hand handlebar switch cluster were both required on '76 twins. Those new switch clusters connected with AMP connectors, which weren't interchangeable with the previous bullets and snap connectors. Therefore, it's this change that's the reason for the different '76-'78 main harness part number?

I submit if Rod uses T140E switch without the diode he will have the problems he has described.
Errrm ...

I seem to have sorted the problem out.
What diode?
As you know, a diode only allows electricity to pass in one direction.

The 31788 lighting switch fitted to '78 T140E's had only one input wire - the White wire switched by the ignition switch attached to terminal #1, The only other wires attached to the switch were Brown/Green outputs from terminal #7 to tail, pilot, speedo. 'n' tacho. bulbs and Blue output from terminal #8 to the dipswitch. As the switch had only one input, for what does it need a diode in the White wire? There isn't any other input that could send electricity the 'wrong way' - from the lighting switch down the White wire to the ignition switch.

From his posts, Rod's bike now has: Brown/Green outputs from terminal #7 to tail, pilot, speedo. 'n' tacho. bulbs and Blue output from terminal #8 to the dipswitch ... but Brown/Blue unswitched input from the ignition switch to terminal #4. This is (pretty-much) how 31788 was wired '68-'74 ... when it also didn't have a connected diode or White wires.

Again as the switch has only one input, which isn't a White wire, for what does his bike need a diode or its extra White wires?

Hth.

Regards,
 

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K....
I'am sorry if I've failed to answer the specific questions that you have asked. I seem to have sorted the problem out. I now have oil pressure light and tail light with ignition switched on, and (fire at points).
The toggle switch (31788) activates the pilot lamp (first position) and main beam (second position) with (NO fire at the POINTS) , key NOT switched on. High beam also works when switched from handlebar switchgear.
I have disconnected the white wire from the toggle switch altogether.
I will repost with switch terminal numbers I've connected.
While neither a mechanic nor an electrician (God bless J. Lucas) I've been the sole caregiver to this machine for 42 years.
I'll now plug in my toaster and go for a ride...


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Rod

I have been praying you and yours escaped the devastation that hit Macon. Please let the Forum know you and yours are alright.

If you feel a personal affront to my last post I apologize.

I was not including you with the dipshifts I have had the pleasure to encounter in the last 40 plus years of selling Triumph's,Yamaha's or Triumph/BSA/Norton parts. Most customers were OK In fact the ones i had the least problems were the 1 percenter's

I was selling 78 T140V & E models when they were new. I purchased a new 79 XS650F in 12/78 as a new Triumph wasn't in the budget. That one is still in the garage parked since the fall of '82 with 41,000 mi on the clock. I have only had my '78 since April of '89 I wont bore you with our history. My '70 T120 I obtained in August of 78 again I will not bore you with the story . The description of the machine as acquired is no side or center stand, Honda Gold Wing front fender and headlight, 'interesting' rear fender, when I lifted the bike up the wheel and forks fell off due to a bad mix of parts, earlier seat,plugged carb. loose head Etc Etc Etc. It takes a certain attitude to survive ownership of any Triumph 40/41 years. (Not to be picky but you will have owned your bike 41 years in June)

With all that said you have the machine electrically functional you DO NOT have the problem sorted out.

The pilot bulb should operate when he Main is on.

The questions I asked were to try to figure out where your problems were. The harness question was to see if you had the original harness with MAYBE THE DIODE YOU KNOW NADA ABOUT ATTACHED.

If you are happy with the machine is functioning God Bless You. Be aware if you try change to an H-4 bulb you may immediately pop the Fuse

By the way if you wish ti see my 70 is one of the T120RT's in Triumph In America

As aside if an one knows how the Tyner/Hixson/Murray Hills area of Chattanooga fared in the Tornadoes I would appreciate an update I used to go to the Church behind Triumph of Chattanooga course that was over 50 years ago.

K
 
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