Tag Archives: wiring harness

Triumph TR6 Courtesy Light

The factory Triumph TR6 courtesy light is originally installed on a plinth, mounted on the driveshaft tunnel cover between the seats, toward the back.  Unfortunately, the new driveshaft cover in bowtie6 is different from the original and the plinth does not fit so well.

Since the two floorboard kick panels are scratch built, I figured why not mount a courtesy light on each one.  I had this all working after I wired the car up for the first time, but when I installed the Ecotec, all that came out because I had to build a new fuse panel.  I left the lights on the kick panels, but never wired them up.


The reason I never wired this back up was the lack of a proper 12v source to test with.  Sure, take the battery out, put some leads on it and test away.  Too much trouble.  Well, remember that NOCO Genius 10 Battery Charger that I bought earlier this year?  It has a setting that supplies 12v to the terminals.  You can see the little red 12v light below…

I wired up the circuit and voila, after a few tries, got it working…

You can see in the photo above, the terminals, my buggered up wiring and the two lights in action.  Job done!

Well…  Not so fast.  Two problems came up.

First Problem

My original wiring worked well, but my initial solution did not take into account the fact you can flip a little switch on each light to turn it on when the doors are shut.

Duh!  After scratching my head a little, all it took was a few tests with my multimeter and now I have the proper wiring on paper.

Second Problem

When I wired bowtie6 up, I used WeatherPack connectors for everything.  All terminals were crimped, soldered and covered with shrink wrap (where necessary).  You can see the three terminal WeatherPack connector in the photo above on my kick panels.  All this was put together at my cousin Jim’s shop – he has a whole array of wire, connectors and terminals.  Since I have a few other circuits to rework, I needed a small kit of Weather Pack’s rather than ordering in bulk.  This is where I found CustomConnectorKits and placed an order for one of their smaller kits.

If you are a regular here, you know I very seldom “plug” anyone.  These folks were gracious enough to send me my kit priority mail (I did not ask for that) so this is my way of thanking them for the super fast service.  I will have my kit in the next couple of days!  This is highly appreciated.

The next step will be to add a new circuit to the fusebox with a constant 12v supply and make up my connectors using my new Weather Pack ends.  In the middle of doing my research, I found replacement LED festoon bulbs – they will be certainly brighter and won’t get hot.  There is a set of these bulbs on the way too.

I have some time off from work in the next few days, so I’ll be putting this all together next.  I’ll have an update article soon.

As always, be safe…

Good Electrical Ground

A good electrical ground.

How many times have we read about the need of having a good electrical ground in classic cars?  Well, I’ve had my fair share of bad electrical grounds through the years and this weekend I fell victim to one.

Weekends are my time to enjoy driving bowtie6 and this past Saturday was no exception.  At a red light not far from the house some dipshit was fiddling with his phone instead of paying attention to traffic.  I reached down below the dash and tapped the single-pole momentary-on switch that controls the horn…

Nada.  Nothing.  Horn did not work.  At this point I had the default Whiskey-Tango-Foxtrot expression on my face.  Damn!  Electrical gremlins.  Fist thing that pops in my head is failure to have a good electrical ground.

And so, when I get back home I check the fuse panel under the dash that I made and controls all electrical circuits under the bonnet (click here for a more detailed post).

IMG_2825I checked all fuses and they all passed with no issues.  Then, I pulled each one out and made sure all connections were in order.  I know, the wiring is a bit busy – but this is rather hard work to do especially in the tight confines of the passenger’s side footwell.  I suppose this is what “bespoke” is all about!  😉

So, next was to go through the main power box.  This is located in the engine compartment (click here for more details).

IMG_2824As you can see, here is the main power distribution block in bowtie6.  The six red-capped affairs on the bottom are circuit breakers.  They feed hard voltage to each purple relay.  In addition there is another fuse panel located behind the relays as well as the engine’s PCM.  After careful inspection all this checked out just fine.  When I flipped the switch under the dash for the horn, the “horn” relay clicked as expected.  Still no horn – rats!

Which brings us to the next photo (a closeup of the featured image above):

IMG_2826 closeupThe entire circuit governing both horns relies on the ground made by the connector to the body.  As it turns out, I pulled this connector and ensured there was no rust.  Sure enough, after cleaning the connection, adding a little de-electric grease, and plugging the connector back in place all worked just fine.

And there you have it, the root of all evil… The lack of a good electrical ground.

bowtie6‘s Custom Wiring – Inside the Cab

The last and final installment of the bowtie6‘s custom wiring takes us to the inside of the cab.  This will be the last on wiring – I know this is getting boring but I just want to show what can be done with a little creative thinking.

So what do we have here?

The picture above shows the quilted maple dash we made, it is mounted to an aluminium backing dash which in turn is bolted to the stock TR6 mounts.  The vent is fully operational with a bit of a twist – I’ll have to write about this later…

Behind all this you can see what I call the “cab” wiring.  Here are two spade fuse housings holding 7 of 8 fuses.  The ones on the left side are constant “on”; the ones on the right are switched.  In the middle you can see four relays.  Here is a closeup:

Why the missing fuse?  I am not completely done with the interior wiring and this circuit will be used at a later date when I add the final details to the inside:  fully operational door activated interior lighting.

Relays & Fuses

Four relays are mounted on this plate.  They control the following:

  • Heater and windshield wipers.
  • Turn signals – one relay controls “left”; the other controls “right”.
  • Parking lights.

As with all the other switches, the heater and windshield wiper switches make “ground”.  They in turn activate the electromagnet on the relays.  The B+ to the electromagnet side of the relays are fed by the fuses on either side.  I did not use circuit breakers here, I just used the spade fuese.

The turn signals are controlled by a stock TR6 turn signal stalk.  The turn signals feed goes through a “blinker” switch and from there, a wire is sent forward to control the front signals and a matching wire is sent rearward to the back turn signals.

The same process is done for the parking lights.  The parking lights and headlights are both controlled by a universal park-light/headlight switch.  I bought this from the same supplier I bought all the wiring from and is commonly used in street rods.

Two banks of fuses flank the relays.  The left ones are constant “ON” and supply power to the ignition switch, ECM and dash clock.  Yes, we have a clock in bowtie6!  I’ll have a writeup on the VDO gauges soon.

On the right, the fuses are switched “ON”.  These fuses supply such things are the control side to the relays as well as instrumentation lights and such.

In Summary

Once again, I guess you must be saying “this guy has a lot of time on his hands”.  Then again I wanted to make this flawless and 100% reliable.  I imagine you are asking yourself if this can be “seen”.  Well, I made sure to hide this as best as possible.  You have to get on your knees to see the fuse panel.  If you don’t know about it, you will never see it.  Finally it is mounted high enough that it does not get in the way of your knees and/or feet.

Another great advantage about all this is that all three panels are very easily accessible.  If for some reason a fuse blows it can be easily found and replaced.  When I built bowtie6 the first time, the fuse panel was in one central location.  It was VERY difficult to get to and was not easily serviceable.  I made sure to make it this time very “user friendly”.

And Then There is More…

See anything “unusual” in the pictures above?  There are two small details that do not exist in a stock 1972 Triumph TR6.  See if you can spot them.

If not, stay tuned and there will be more about this soon…


bowtie6‘s Custom Wiring – Trunk

The last post talked about the harness and fuse box under the hood.  Today’s post shows the wiring in the trunk.

Since we are far from “original”, I wired up bowtie6 in a practical way.  There is a fusebox in the engine compartment (as discussed previously), one in the cab compartment (to be discussed) and one in the trunk (discussed here). Why go through all this trouble?

Well, for starters I wanted to keep things simple.  But mainly because there was not enough room underneath the hood!  Besides, it makes sense to control things where they belong and in the trunk there are several things to control…


The Optima Red-Top dry cell battery in bowtie6 is mounted in an aluminium enclosure pictured above.  The B+ terminal has a welding machine cable attached to it and it runs inside the TR6’s cab and ties into the firewall post.  The ground terminal is also a welding machine cable going through the body and securely bolted to the frame.  In the engine compartment, there are two more welding machine cables grounding the body and the engine to the frame. Finally, there is a B+ lead from the battery to two circuit breakers mounted in a special mount that control the following:

  1. Fuel Pump
  2. Backup Lights
  3. Brake Lights

Fuel Pump

The ECOTEC needs a high pressure fuel supply.  This comes from a GM high pressure pump as fitted to late-model Corvettes.  We used that pump because it is very small, has a filter “sock” and can be mounted in a small enclosure.  In the picture above you can see the fuel pump enclosure – that is the aluminium box resting on the trunk’s floor.  I’ve written about this before but basically that is an external tank plumbed to the main custom made all aluminium fuel tank.  We have about a 300 mile range in city driving with this setup.  I am sure it will be more once we do a long, highway trip.

The picture above shows two circuit breakers and three relays.  The fuel pump has one of the relays and one of the circuit breakers.  The control side of the relay is fed from a signal from the ECM.  When done right, the ECM sends a 5 second signal and energizes the pump.  This primes the fuel rail and gets things ready for ignition.  Once the engine fires, the ECM re-energizes the relay and that keeps the pump running until the ignition switch is turned off.

Backup Lights

The AISIN 5 speed gearbox has a built in switch that makes ground when the stick engages reverse.  I took advantage of this to make the TR6’s backup lights work.  Basically since this is a switch and it makes ground, I wired this into the control circuit of a relay.  This minimizes wear on the switch and voilà, we have backup lights.

Brake Lights

Ah!  Brake lights!! As you had guessed, I used a relay to run the brake lights.  As with the fuel pump and backup lights there is a hard voltage circuit from B+ on the battery to the relay.  This is controlled by breaking ground on the brake pedal switch.  Simple.  Brakes work flawlessly and will be there forever – the brake switch breaks ground.

 In Summary

Once again, I realize this is borderline overkill.  However, this makes things very simple and easy to fix if need be.  Setting this back circuitry together took little time and works like a charm.  As with the engine compartment fuse box, I added red “booties” to the circuit breakers.  You can also see the trunk floor is fully covered in black carpet now.

Here is a closeup of the rear wiring:

If you look close enough you will see several things here…

  • The lid to the battery box.  The box is made from aluminium and bolted securely to the side floor of the trunk.  This is mounted on the passenger’s side to even out weight distribution.  As mentioned previously, the battery is a dry cell Red Top Optima battery.  They are very durable and although they are expensive, they are very worth the cost.
  • The black plastic background.  That is ABS material pre-bent and cut to fit the sides of the trunk.  There is one on all sides, including the inside back of the trunk.  I used this because it is very easy to work with and can be shaped with simple tools such as scissors and a break.  This stuff is also very durable and looks very clean.  Much superior to the crappy cardboard “trunk liner” kits sold by the Big Three vendors.
  • The aluminium plate holds three relays and two circuit breakers.  I’ve discussed these above.
  • Finally, if you really look close you can see two rubber hoses right behind the circuit breakers.  What is this all about?  Well, my bowtie6 is from the very fine 1972 vintage.  In 1972 a special “tank” was affixed to the inside of the passenger’s side trunk.  This tank had two lines attached to it.  The first line came from a vent on the fuel filler neck.  The other line was routed to the intake.  This ensured all fuel tank fumes get routed back to the engine.  This has been retained and is fully operational in bowtie6.

Attention to detail?  Hell yes.

There are so many small details on bowtie6 that get overlooked!  However, I know they are there and this makes the difference.  With this TR6, there is not only killer looks in the form of a very shiny paint job, a powerful engine and a great handling frame but there are also countless details that separate this from even “restored” examples…


bowtie6‘s Custom Wiring – Under the Hood

After nearly 1,000 miles on bowtie6 since the ECOTEC conversion, I have a ton of stuff to detail out.  This is where you spend tons of time for little to show for.  Sure, I could just leave it “as is”, but there is no fun in that.  Sweating the details is what sets my car apart from all others.

Today, I spent some hours refining things in the main fuse box under the hood.  I’m not 100% done with it yet, but I figured I’d take a few pictures of it so far and write about it.  Maybe somebody might get some inspiration from all this work.

This is what the main engine-compartment fuse box looks like…

Big deal, huh?  Well the silver box is located in the area where the windshield washer bottle used to be and also the area where the dealer-installed air conditioning system was installed.  What is so special about this?  Well other than the fact this is all hand-made aluminium, take a look at what is inside the box…

Now it gets interesting…

  • Starting at the bottom of the picture are six circuit breakers.  Today, I added the little red “booties” to prevent any short circuits.  The middle breaker shows what they look like under the red “bootie”.  Two terminals stick out and this is what the “booties” protect.  Don’t want any electrical short circuits to happen here!
  • Above the circuit breakers are seven relays.  They control the most important basic functions underneath the hood.
  • Above that towards the right is a fuse panel with 8 modern spade type fuses.  These are used on the control side of the relays.  Basically they make the electromagnets in the relays trip when a switch makes ground.
  • The finned box with the three big connectors is the Engine Control Module (ECM) running the show on the ECOTEC.  This is “factory” supplied from the donor engine.
  • To the left of the ECM is the solid state electric fan controller.

Circuit Breakers

These guys act as fuses.  They feed the hard voltage from the B+ terminal through the firewall to the relays.  What B+ terminal?  Since the battery is located in the trunk, we ran a welding-machine cable from the battery’s B+ terminal through the firewall by means of an insulated bolt.  This is where we get voltage to the underhood fuse box and also to the inside of the cab (on the inside side of the bolt)

This is a close up of what this all looks like:

At the very left you see the post where full B+ voltage is supplied to the circuit breakers.  The body and frame is ground so how does this keep from shorting out?  The bolt is fully enclosed in a phenolic ring thus insulating the terminal.  On one side of the circuit breakers is the hot B+ terminal – this is the one nearest to the camera.  On the other terminal is the supply of power to the relays shown above.  On the middle of each circuit breaker you can see the little black dot that acts as a “reset” button.  I used circuit breakers because these are 100% essential to the electrical operation of the system.  If they trip a simple push of the black “reset” button has me back in business.


Seven relays run the show for the main switched hot lead, ECM, headlights switch, high/low beam, electric fan, horn, starter and ignition switch.  All the switches on bowtie6 break ground.  There is no hard voltage going through any switches.  The advantage of this is longevity.

So basically when a switch is activated, it “makes” ground.  This in turn causes the electromagnet in the relay to trip and that makes the circuit hot.  There is no hard voltage through any switch except for one:  ignition.  I am using an industrial strength switch for this, rated for much higher amperage than what the Optima battery delivers.  This will last past my lifetime.


There are 8 fuses under the hood.  These supply power to the control side of the relays as well as to the ECM and the electric fan controller.  I used modern style fuse housings and bladed fuses.  Glass fuses are just too poorly made and prone to failure and that makes them very unreliable.  Not acceptable for bowtie6.

ECM and Engine Harness

The “brains” controlling the ECOTEC is the GM factory E67 ECM.  The wiring from the ECM to the multitude of sensors on the ECOTEC is basically a factory harness from a Chevy HHR, modified to act as a Pontiac Solstice.  We modified the harness by changing pin-outs and removing unnecessary circuits.  This makes the harness much simpler to work with.  Furthermore we cut many wires to make them shorter or longer depending on where they were located.  This is the beauty of doing it “yourself” as opposed to buying something.  Anybody can “buy” stuff…  It takes talent to make you own.

Like I said before, the harness came from an HHR.  GM went through a lot of work in making a very durable and well engineered harness.  In my opinion, the quality of the wire is superb and the connectors are not only expensive but of very high quality.  The harness is basically divided into three “plugs” (you can see them in the picture above).  One has 56 pins; the other two have 73 pins.  Not all are needed though and having a Factory Service Manual will be instrumental in determining what circuits are kept and which need to go.

To make the ECM work outside of the “factory” setup, one must remove the VATS.  This is the “Vehicle Anti-Theft System”.  You do this either sending the ECM out to somebody or by using a software package such as HP Tuners.  We used HP Tuners.  This also enabled us to tune the ECM.

Speaking of the ECM:  make sure you get the right one.  The ECM’s come in two varieties depending upon the type of gearbox used.  An automatic gearbox ECM will not work on a 5 speed gearbox.  Also, there are certain E67’s that will just won’t work.  You will need to make sure you get the one with the right OS, otherwise it won’t work.  This is why it is very important to get the ECM that came from the donor vehicle.

Solid State Fan Controller

This little device is trick.  It has a built in relay and has B+, ground and a wire hooked up to the temp sensor on the block.  This is where the device gets its temp signal.  Here is the beauty of this device:  on 99.99% of all street rods I see, folks stick a nasty looking probe in the middle of the radiator core.  This not only looks awful but eventually wears a spot in the radiator’s core causing it to leak.  I think this way to wire a controller not only looks crappy as hell but is very sloppy.  The controller we use is not cheap, but it has a fully adjustable rotary knob that enables setting the proper temp to kick the fan on.   In the photo above the controller sits on top of the ECM but I am planning to move it to a different location to make it look a little more elegant.  Again, it is the details that count!

In Summary

I realize this is not everybody’s cup of tea (a polite way of saying “I don’t like it”) but once again this works for me and the car has been built to suit me not anyone else.  I wired the thing, I know each circuit and quite frankly I am proud to say it is bullet proof.  I blew a fuse one time, but that was my dumbass-self making a mistake.  Again, one can source a ready made wiring harness but what do you learn by doing that?  I spent a lot of time learning about circuits and how relays, fuses and circuit breakers work.  This takes time but the result is very rewarding.

If you do decide to undertake something like this, there are a few things I would highly recommend:

  • Every single terminal (and there are many) is soldered – nothing just crimped.  This is extremely time consuming but worth every moment you spend on it.  Soldering ensures a perfect connection and if you are going to spend this much time, you want it to be dead-nuts-accurate.
  • I used the expensive shrink wrap that has the sticky stuff inside of it on every joint, every terminal and every splice.  Why?  This makes the connection water and moisture proof.
  • Anytime I had to join parts of the harness, I used Weather Pack connectors.  They are not cheap, take a long time to crimp and assemble but they are water and moisture proof and last forever.  This is the only way to go.  By doing the harness this way you can ensure certain parts can be take apart without removing the whole shebang.  There is a bit of strategy to play here but you will be very happy with the result.
  • I spent quite a bit of resources on only the best quality wire.  All my wire came from an industrial supplier, not from a home-improvement store.  This is industrial strength. The real-deal.  I did this the first time with the V6 and it lasted flawlessly for 5 years.  This time around I expect it to last much longer since we are braking ground instead of switching hard voltage.
  • Relays – buy only the best (mine are Bosch) and don’t be stingy.  Relays are the way to go.  Once you get the basic principle of how they work they are fantastic.  This folks, is not rocket science and is not black magic.  Relays work and if you do it right, they last forever.
  • Use the proper tools.  I say again:  use the proper tools  I used good quality nippers, soldering gun, heat gun and crimping pliers.  The Weather Pack connectors require a special crimper.  Use the best you can afford.  Otherwise you will have crappy connectors and this will lead to electrical problems and the dreaded “Lucas Syndrome” where wiring turns into very expensive blue smoke.

I could write about this forever but then again, I would bore the hell out of you.  If you have any specific questions let me know and I can address them in a separate post.

Go do some wiring!  It is not as complicated as the harness “makers” make you believe it is…  🙂