Post-project info, tips and tricks: read this first!
This is a post-completion edit-in-progress; the original first post begins below...but this will be an easy way to make sense of all of the information that was discussed and the wrong turns that were taken, in the hopes that the next person who attempts a 12V trailer circuit will have an easier time than I did. This being said, we can proceed to A Few Short Words On:
The Overall Point
My purpose in constructing a 12V trailer-light setup was - obviously - to pull a 12V trailer behind a 24V Cruiser...but it was also to get a functional 12V system on board, and to keep that system as low-profile and reliable as is possible; to be honest, I didn't want any portion of it to be easily or readily visible, but I still wanted easy access to the components. Locating the bulk of the items within the left rear quarterpanel and accessing them via the removal of the interior trim panel accomplished this, albeit at a cost of some light fabrication and medium-strength profanity. Other locations are available.
Components
I elected to keep factory/OEM quality wherever possible; this presented several challenges. Relays, wire, connectors, modules... you name it: they were all somewhat difficult to find in the US on short notice. If you also eject to go for an OEM level of construction, you'll need to plan ahead and find a few things that confounded me for a bit:
The electrical tools are standard: multimeter, strippers, etc. You'll want an actual cable cutter if you don't have one - Klein does a good job with this one - and for all of the small terminals, you'll want to pick up some decent crimpers. Also, be wary of the primary 24V leads: depending on how you route/size them and where you place your converter, you could end up with 6AWG - if not larger - on either/both sides of that unit. For that size terminal a hydraulic crimper is almost necessary, and they aren't cheap; I had battery cables and winch cables to build as well, so I bought a hydraulic crimper from Temco, but you can hammer crimp them as well...or just have someone else make the cable. Either way, be forewarned.
To be continued...
I've been futzing with the search function and not coming up with any good answers, so that's my probably my fault and ineptitude...but nonetheless, I'm having a real time of it trying to get some basic answers on trailer wiring on my 73.
I'd like to get a 7-pin connector and a brake controller installed, but I'm not finding a lot of info on how anyone has done it. I know there's absolutely no such thing as a kit, so I know I'll have to figure something out for myself...but the main question is this: am I going to have to run a separate 12v drop to the brakes themselves and leave the wiring at the 24v of the indicators and stop lamps? If so - or if not so - what's the best method for the wiring pulls to do so? Direct from the battery (or a rear sub-panel) for the brakes, and some careful tie-ins to the indicators/stops? I know the electrics can be fussy on these, so I'm really not interested in hacking it all apart and screwing it up...so I'm inquiring before I start cutting wires.
Also, I saw a couple of posts here and there that said the braked towing capacity on the mid-wheelbase models was 3500kg, like the longer ones. Is this correct? It doesn't seem correct, to me.
Thanks in advance for any help.
This is a post-completion edit-in-progress; the original first post begins below...but this will be an easy way to make sense of all of the information that was discussed and the wrong turns that were taken, in the hopes that the next person who attempts a 12V trailer circuit will have an easier time than I did. This being said, we can proceed to A Few Short Words On:
The Overall Point
My purpose in constructing a 12V trailer-light setup was - obviously - to pull a 12V trailer behind a 24V Cruiser...but it was also to get a functional 12V system on board, and to keep that system as low-profile and reliable as is possible; to be honest, I didn't want any portion of it to be easily or readily visible, but I still wanted easy access to the components. Locating the bulk of the items within the left rear quarterpanel and accessing them via the removal of the interior trim panel accomplished this, albeit at a cost of some light fabrication and medium-strength profanity. Other locations are available.
Components
I elected to keep factory/OEM quality wherever possible; this presented several challenges. Relays, wire, connectors, modules... you name it: they were all somewhat difficult to find in the US on short notice. If you also eject to go for an OEM level of construction, you'll need to plan ahead and find a few things that confounded me for a bit:
- Factory taillight connectors. The correct unit is the Sumitomo MT-series .090 6-Position Special-A. I'm not making that name up, by the way: you'll need a half dozen of them, and you can find them here, at Eastern Beaver.
- If you follow my Diode Reversal Variant (to be noted below) you'll need to find a diode-flavored ISO mini relay - four of them, to be exact - and if those are all you can find, you'll have to follow the Reversal Variant. The Bosch 0332209204 are correct for this application.
- Factory-spec wiring for the taillight intermediate harness - i.e. the link you insert between the separated factory connectors in order to shunt various signals into your relay block - is available from LSWiring. You'll need 20AWG in whatever colors you find in your harness for the following circuits: both turn signals, the brake/stop, the running lights, and the ground/earth.
- A 4-position block for the ISO mini relays. Hella makes a nice one; other options are available. Word to the unwise: buy extra spades.
- The actual 12V converter and fuse block are somewhat immaterial, as long as they cover your needs...so before you get started, plan out as much of your 12V bus as is possible and size things accordingly. I bought a 30-amp Victron Orion unit - the 24/12-30, to be exact - and I paired that with a Blue Sea 5025 fuse block. Both will fit in the space allowed.
- I'm not going to place a link to any specific battery cable and/or primary wire, so just buy the best marine-grade, pre-tinned stuff that you can get. Check local marine suppliers, if you have any: often, you can get short pieces for 30% to 50% off.
The electrical tools are standard: multimeter, strippers, etc. You'll want an actual cable cutter if you don't have one - Klein does a good job with this one - and for all of the small terminals, you'll want to pick up some decent crimpers. Also, be wary of the primary 24V leads: depending on how you route/size them and where you place your converter, you could end up with 6AWG - if not larger - on either/both sides of that unit. For that size terminal a hydraulic crimper is almost necessary, and they aren't cheap; I had battery cables and winch cables to build as well, so I bought a hydraulic crimper from Temco, but you can hammer crimp them as well...or just have someone else make the cable. Either way, be forewarned.
To be continued...
I've been futzing with the search function and not coming up with any good answers, so that's my probably my fault and ineptitude...but nonetheless, I'm having a real time of it trying to get some basic answers on trailer wiring on my 73.
I'd like to get a 7-pin connector and a brake controller installed, but I'm not finding a lot of info on how anyone has done it. I know there's absolutely no such thing as a kit, so I know I'll have to figure something out for myself...but the main question is this: am I going to have to run a separate 12v drop to the brakes themselves and leave the wiring at the 24v of the indicators and stop lamps? If so - or if not so - what's the best method for the wiring pulls to do so? Direct from the battery (or a rear sub-panel) for the brakes, and some careful tie-ins to the indicators/stops? I know the electrics can be fussy on these, so I'm really not interested in hacking it all apart and screwing it up...so I'm inquiring before I start cutting wires.
Also, I saw a couple of posts here and there that said the braked towing capacity on the mid-wheelbase models was 3500kg, like the longer ones. Is this correct? It doesn't seem correct, to me.
Thanks in advance for any help.
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