Legacy trailer plug history

Chatty

Well-Known Member
any dates for when various plugs got retired though?
There isn't any date for retirement as such - you can still order a trailer with a 5 or 7 pin round plug if you want to.

Round plugs haven't been retired, they have just become less popular over the years. Look at it the same way as Dencorub, almost no one uses it anymore because it makes you smell like old people, but Chemist Warehouse still stocks it.
Round plugs and sockets are the same - no one uses them because it makes you look like a Grey Nomad who still lives in the 1970s, but Supercheap Auto still stock them.

In fact, my Sierra (2018) came with a large 7 pin round socket and a 12 pin flat socket.
 

linuxfan66

Active Member
There isn't any date for retirement as such - you can still order a trailer with a 5 or 7 pin round plug if you want to.

Round plugs haven't been retired, they have just become less popular over the years. Look at it the same way as Dencorub, almost no one uses it anymore because it makes you smell like old people, but Chemist Warehouse still stocks it.
Round plugs and sockets are the same - no one uses them because it makes you look like a Grey Nomad who still lives in the 1970s, but Supercheap Auto still stock them.

In fact, my Sierra (2018) came with a large 7 pin round socket and a 12 pin flat socket.
so when was the last time you had a new car with a 5 or 6 pin though
 

Chatty

Well-Known Member
so when was the last time you had a new car with a 5 or 6 pin though
When was the last time you ordered a vehicle with one?
Trailer sockets are a dealer fitted item on most vehicles and they will fit whatever you ask for.

Round plugs and sockets have not been "retired" - they are still used in the trucking industry for trailer connections.
And, there is no process within the industry for saying "Thou shalt not fit 5 pin round plugs and sockets to vehicles from 1 January 2023" - unless the ADRs and/or associated state regulations decree such, and I can't see that happening.
Five pin round has simply fallen out of favour with (light vehicle) consumers and trailer manufacturers as it no longer meets modern needs for more connections between the tug and trailer. For this reason the 12 pin flat plug is becoming a de-facto standard on caravans now - this in turn leads to the 7 pin round being less desirable as the 7 pin flat plug is compatible with the 12 pin flat socket - meaning you can run one socket on your tow vehicle.

You might as well argue that 7 pin flat has been "retired" because of 12 pin flat being used so much. It's simply not a valid statement.

Personally, in some ways I think the 5/7 round plugs and sockets still have a place - they have a much better contact area and current capacity (especially the large versions) than the 7/12 pin flat plugs and sockets. This is why they are used for trucks and semi-trailers trailer connections.
 

linuxfan66

Active Member
When was the last time you ordered a vehicle with one?
Trailer sockets are a dealer fitted item on most vehicles and they will fit whatever you ask for.

Round plugs and sockets have not been "retired" - they are still used in the trucking industry for trailer connections.
And, there is no process within the industry for saying "Thou shalt not fit 5 pin round plugs and sockets to vehicles from 1 January 2023" - unless the ADRs and/or associated state regulations decree such, and I can't see that happening.
Five pin round has simply fallen out of favour with (light vehicle) consumers and trailer manufacturers as it no longer meets modern needs for more connections between the tug and trailer. For this reason the 12 pin flat plug is becoming a de-facto standard on caravans now - this in turn leads to the 7 pin round being less desirable as the 7 pin flat plug is compatible with the 12 pin flat socket - meaning you can run one socket on your tow vehicle.

You might as well argue that 7 pin flat has been "retired" because of 12 pin flat being used so much. It's simply not a valid statement.

Personally, in some ways I think the 5/7 round plugs and sockets still have a place - they have a much better contact area and current capacity (especially the large versions) than the 7/12 pin flat plugs and sockets. This is why they are used for trucks and semi-trailers trailer connections.
i never said 7 pin was retired. i meant show me the newest car in australia with the factory towing kit having a 5pin.
 

Mick_Marsh

Active Member
i never said 7 pin was retired. i meant show me the newest car in australia with the factory towing kit having a 5pin.
I bet you regret using the word "retired", then.
any dates for when various plugs got retired though?
What do the factory install as a towing kit? Factory fitted, not dealer fitted.
Do you have a choice? Is there a check box on the order form?

With an early round type, the wiring is different between a 5 pin and a 7 pin. You are not meant to tow a trailer fitted with electric brakes with a vehicle not fitted to do so.
 

Chatty

Well-Known Member
i never said 7 pin was retired. i meant show me the newest car in australia with the factory towing kit having a 5pin.
I haven't seen a factory fitted tow kit in about 20 years - all that I've seen have been dealer fitted, largely because most new vehicles are delivered from a national stock of vehicles already in the country so a lot of options are left to dealer fitment.
Not saying that factory fitted kits aren't out there, but I think they're a pretty rare beast these days.

Well, apart from my Sierra which came from the factory with a large 7 pin round - but the Yanks do things differently to the rest of us.
 

Chatty

Well-Known Member
You are not meant to tow a trailer fitted with electric brakes with a vehicle not fitted to do so.
But it adds to the excitement if you do :p :eek:
With an early round type, the wiring is different between a 5 pin and a 7 pin.
Large round (Type 1) 5 and 7 pin plugs are interchangeable between sockets as the only difference is the addition of the extra pins in the 12 and 6 o'clock positions. Done so you could tow a trailer fitted with a 5 pin plug on a vehicle with a 7 pin socket.
I stand to be corrected, but I thought the large round 5 pin socket had blanks fitted in the 12 and 6 o'clock positions to prevent a 7 pin plug being inserted? This would be to try to prevent a brake equipped trailer being towed by a non brake equipped vehicle.

Small round (Type 2) 6 and 7 pin plugs and sockets aren't interchangeable in any way, shape or form - not even with a large hammer.

7 pin flats don't care about what's wired and what's not - just plug them in and go - who cares about things like brakes? This is a serious design deficiency in these plugs IMHO.

I don't think I've ever seen the AS/ISO plugs in this chart. But they would add a whole new level of confusion...



1653449002038.png
 

linuxfan66

Active Member
I haven't seen a factory fitted tow kit in about 20 years - all that I've seen have been dealer fitted, largely because most new vehicles are delivered from a national stock of vehicles already in the country so a lot of options are left to dealer fitment.
Not saying that factory fitted kits aren't out there, but I think they're a pretty rare beast these days.

Well, apart from my Sierra which came from the factory with a large 7 pin round - but the Yanks do things differently to the rest of us.
So there isn’t an official Toyota, Nissan, ford branded tow kit stocked by the dealer?
 

Chatty

Well-Known Member
So there isn’t an official Toyota, Nissan, ford branded tow kit stocked by the dealer?
You said "factory fitted" - anything fitted by the dealer is, by definition, not factory fitted.

I think you'll also find that the tow bars fitted by the dealers are almost always Hayman Reese - the last "genuine" Toyauto tow bar I had fitted was Hayman Reese branded.
 

Mick_Marsh

Active Member
But it adds to the excitement if you do :p :eek:

Large round (Type 1) 5 and 7 pin plugs are interchangeable between sockets as the only difference is the addition of the extra pins in the 12 and 6 o'clock positions. Done so you could tow a trailer fitted with a 5 pin plug on a vehicle with a 7 pin socket.
I stand to be corrected, but I thought the large round 5 pin socket had blanks fitted in the 12 and 6 o'clock positions to prevent a 7 pin plug being inserted? This would be to try to prevent a brake equipped trailer being towed by a non brake equipped vehicle.

Small round (Type 2) 6 and 7 pin plugs and sockets aren't interchangeable in any way, shape or form - not even with a large hammer.

7 pin flats don't care about what's wired and what's not - just plug them in and go - who cares about things like brakes? This is a serious design deficiency in these plugs IMHO.

I don't think I've ever seen the AS/ISO plugs in this chart. But they would add a whole new level of confusion...



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It's interesting how your 5 pin plug is missing the left and right indicators but has an electric brake and reverse signal.
 

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linuxfan66

Active Member
You said "factory fitted" - anything fitted by the dealer is, by definition, not factory fitted.

I think you'll also find that the tow bars fitted by the dealers are almost always Hayman Reese - the last "genuine" Toyauto tow bar I had fitted was Hayman Reese branded.
I apologise my definition factory I considered any manufacturers genuine accessories to be as good as factory. Should have clarified this. Anything with the manufacturers name on it you could get fitted before receiving it
 

Chatty

Well-Known Member
I apologise my definition factory I considered any manufacturers genuine accessories to be as good as factory. Should have clarified this. Anything with the manufacturers name on it you could get fitted before receiving it
Sorry, but you're missing an important distinction here - it doesn't matter whether something has the manufacturer's name on it if it is fitted by the dealer - as the dealer will always fit what is requested by the customer. If you ask for a 7 pin flat socket, that's what you'll get, regardless of whether or not it is part of the "genuine" package. And while I have seen towbars with manufacturers names on them (usually a re-branded Hayman Reese or Milford) I have yet to see a "genuine" trailer socket.
 

Chatty

Well-Known Member
It's interesting how your 5 pin plug is missing the left and right indicators but has an electric brake and reverse signal.
I think this is an American chart - it was the first one I found that demonstrated the different plug/socket sizes and configurations, so I grabbed it without looking closely.
Typically American vehicles flash the stop lights on one side or the other for the indicators - that's one of the problem areas in the RHD conversion of the American trucks as the rear light lenses don't have an orange indicator section.
 

Mick_Marsh

Active Member
I think this is an American chart - it was the first one I found that demonstrated the different plug/socket sizes and configurations, so I grabbed it without looking closely.
Typically American vehicles flash the stop lights on one side or the other for the indicators - that's one of the problem areas in the RHD conversion of the American trucks as the rear light lenses don't have an orange indicator section.
Something is still required to flash. It still requires a left and right signal.
I would say it is more than likely that the chart was an error.

But, the point is, do you see the difference in wiring between the 7 pin and 5 pin round?
 

boobook

Well-Known Member
After reading the last page or so, I think I know less about trailer plugs than I did a week ago.

LOL.
 

linuxfan66

Active Member
all i wanted to know was the last time a factory/dealer default car had a 5pin tow connector without asking for it specifically...
 

Chatty

Well-Known Member
Something is still required to flash. It still requires a left and right signal.
I would say it is more than likely that the chart was an error.

But, the point is, do you see the difference in wiring between the 7 pin and 5 pin round?
It depends if you go by the numbers or the colours - the colours seem to make more sense than the numbers. The numbers on the plug diagrams look like just pin numbers which appear to have no correlation to the connection numbers in the table.
Going by the colours, it all appears to make sense. At least to me.
 
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