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Chris and I do not do much night time driving in our TRs. However, if you attend events such as The Roadster Factory’s Summer Party, you are always driving in the dark on the return trip from various events. The first time this happened, Chris immediately insisted her TR6 needed a pair of driving lights. After much discussion, I convinced her to try a better headlight setup and if that did not bring about an improvement, we could later add the driving lights. The Winter 2014/2015 issue of Ragtop (club magazine for the Toronto Triumph Club) featured an excellent piece by Terence McKillen that covered issues associated with LED and HID lighting units and serves as a good read when contemplating changes to the lighting system

When looking to increase the amount of light thrown down on the road ahead, thoughts usually turn to reflectors and bulbs as the seemingly obvious cause of the problem. If you look at the wiring diagram (Photo 1) for your TR, you will note that before the power can get from the battery to the lighting unit, the current must travel through several connectors and two switches. Each of those connections and the switches can cause a slight drop off in the current passing through. Additionally, full power through an aging headlamp switch, can cause a switch failure resulting in the need for a part that may have to be adapted to work if true originals are no longer available. Incorporating inexpensive, modern relays into the system can allow the relay to activate the headlamps and power to be supplied directly from the relay with no wiring connections in between. The result is greatly decreased power flowing through the switch and greatly increased power arriving at the bulb filament.

There are two ways to go about solving this problem. The first is to purchase a complete kit such as Advanced Auto Wire’s Headlight Relay Kit. Moss Motors, Victoria British, Painless, and others provide similar kits. The second would be to build the equivalent of a kit using individually purchased components. The revised wiring circuits, as suggested by AAW are shown in Photo 2. Individually sourced components will be covered in a future Ragtop issue. Note how the previously identified problems have been addressed in Photo 2. Power is now switched to the lighting element via a modern, inexpensive relay. Other than the fuse, the power is supplied to the filament via a continuous run of wire with none of the barrel connections inherent in the original wiring. Each lighting element is powered via a separate wire. Now, instead of the TR lighting switch handling the full demand of the lighting elements, the switch only carries minimal power sufficient to activate the relays. Additionally, each headlamp (right and left) and each beam (high and low) are now separately fused using readily available, modern fuses. 

The AAW harness is shown in Photo 3 and as the photo shows, everything needed is included, other than panel mounting bolts, some wire wrap (if desired) and maybe special connectors if you choose to make electrical connections that differ slightly. In my case, I did use slightly larger ring connectors to suit my needs. 

The beauty of this setup is that you do not really have to cut any wires if you do not want to, thus allowing reversion to original in the future if you so choose. Each of the connections to the new wiring panel can be made at an existing bullet barrel connection or by attaching a ring connector to an existing terminal. Simply unplug the existing wire, solder a bullet connector to the new wire, and plug the new wire into the old barrel connector.

As with any electrical work, be sure to disconnect your battery leads before working on the electrical connections. Before cutting any wires, soldering any connections, or drilling any holes; layout the entire assembly to ensure wire lengths, connections and mounting points will all work as planned!

The first task will be to determine where you want the panel attached. Do you want to protect the circuits with an inside installation? If an engine bay location is selected, do you want to use a watertight enclosure? In my case, I used the engine bay for the TR6 (shown in Photo 4), 

 water tight enclosure (WC25-Photo 5) for the TR4, and an engine bay enclosure (WC35) for the entire fuse panel for rewiring the TR4A. If using an enclosure, remember you may need to replace a relay at some point so either allow for removal of the panel or a larger case so there is room to remove and replace a relay. In the TR6, the board fits nicely on the horizontal shelf adjacent to the firewall on the passenger side of the engine compartment. Using the mounting board holes as a template and a scratch awl, the locations of mounting holes were marked. A centre punch was then used to further indent the hole locations and then four holes were drilled through the shelf. Drill bit size will be determined by the requirements of the bolt or rivet method of attachment you select. Attachment bolts or rivets are not included in the AAW kit.

As the old construction adage goes, “measure twice, cut once”. Do not cut any of the wires until you have determined where every connection will be made and where the panel board will be mounted. Power to the panel board will be made directly from the battery source. 

The starter solenoid or starter terminal is probably the most convenient terminal for power (Photo 6). I crimped and soldered all wire/connector connections. Before making the connection, a short length of heat shrink tubing was slipped over the wire. Be sure to keep the heat shrink well back of the connection so it does not begin to shrink from the soldering iron heat. I use a heat gun to shrink the tubing but a hair dryer will probably do the job.

You will need to feed this wire to the power terminal on the starter. Our TR6 had a suitably sized hole (Photo 7) exactly where I needed one – on the triangular piece of sheet metal between the firewall and the inner, passenger-side fender. I inserted a grommet (locally sourced) to protect the wire from abrasion. (NOTE: if you go this route, you may need to solder the connection AFTER you run the wire through the hole as the ring terminal may not fit through the hole.)

After the wire is run through the hole, it can be attached to your power source. In my case, I used the terminal on the top side of the starter as shown in Photo 8. [CONCEPT: This connection will provide power straight to your headlamps when they are turned on.]

 The AAW kit uses properly colour coded wires for lighting. The shorter (8 feet) blue/red (U/R) and blue/white (U/W) wires will be connected to wires coming from the low (U/R) beam and high (U/W) beam switch. Bullet connectors will be used on these two wires so that connections with the existing wiring can be made at the existing barrel connectors. The heat shrink tubing was slipped over the stripped U/R wire that had been cut to the appropriate length. The insulation was stripped back to the same length as the depth of the bullet connector.   The connector was crimped around the wire, clamped in a table top vice, and then soldered as in Photo 9.

 After the connection cools, slip the heat shrink tubing over the base of the bullet and heat until the tubing shrinks to seal the soldered connection. Repeat the process for the U/W wire as shown in Photo 10.

 The U/R and U/W wires (one each) run from the dimmer switch to a double snap connector sleeve near the lower front valance on the driver side. There are two similarly colour coded wires running from each double connector, one to each side, left and right. You can remove the wire coming from the dimmer switch and place the included single snap connector sleeve on this wire. The other two wires and the double connector can be removed. You can store these wires, connectors, and headlamp connectors in the event you ever want to revert to the original wiring. [CONCEPT: When the headlamp switch is turned on, power will be provided to the low beam (U/R) relay or to the high beam (U/W) relay depending on the position of the dimmer switch.]

The other wire requiring a ring connector is the ground (B) wire. As with the other wires, I crimped, soldered and heat shrink sealed this connection (Photo 11).

There is a solid ground at the bolt connection for the radiator stay rod. If you use this spot, you may need a larger diameter ring connector here as well. Photo 12 shows this grounding point.

The remaining wire connections will run from the wiring panel directly to the headlamp sockets. If you mounted the panel on the right side of the car, the 12-ft. lengths of wire (1 U/R, 1 U/W) will go to the right side headlamp and the 16-ft. lengths (1 U/R, 1 U/W) will go to the left side. Before making any cuts to the wire, determine the full path the wires will follow and any supports necessary along the way. For the TR6, there is a grommet in the inner fender where the wires will pass through to the headlamp bucket. These wires can be bundled with the other wires where the original headlamp wires were removed.

Starting at the panel (Photo 13), the power feeds from the starter connection were bundled and covered. 

Additionally, the U/R, U/W, and B wires were bundled, covered and routed along the inner fender to the lower right corner of the engine bay (Photo 14). At this point, the wires for the right side are routed through the grommet and into the headlight bucket and the wires for the left side are routed across the valance and through the grommet into the left side headlight bucket (Figure 15). Note, these photos were taken after installation. The headlamp wires were left uncovered until everything was installed, tested, and working correctly. I used corrugated wiring cover available in various sizes from a local auto parts store but vinyl wire wrap tape can also be used.

Wires for the left side are routed across the valance and through the grommet into the left side headlight bucket.

Head lamp rims, lamp retainers, and headlamps were removed in the previous section so that the wires could be pulled through the headlamp buckets. If you wish to keep the original headlamp terminals, you will have to cut the headlamp bucket grommets (Photo 16) to remove them. Otherwise, remove the terminals from the existing wire ends, pull them back through the bucket and insert the new wires into the back of the buckets and through the grommets. Determine how much wire will be needed to attach the end plug but before cutting the wires, verify that you are satisfied with the routing of the wires.

If you damaged the headlamp bucket grommets during the removal process, you can get replacements from British Wiring.

Attach a headlamp plug terminal to each of the three wires on each side. Just as with the earlier connections, the terminals will be crimped and soldered before sealing with heat shrink tubing.

The terminals are then inserted into the headlamp socket. It is important that the terminals are inserted into the correct locations on the headlamp socket in order to achieve maximum illumination. With the headlamp socket rear (wire side) facing you and terminal insertion points on the left, right and top of the plug; the low beam (U/R) inserts on the top, the high beam (U/W) inserts on the right, and the ground (B) inserts on the left. (Photo 18)

The terminals for these three wires (U/R, U/W, B) are inserted into the rear of the headlamp socket. (Photo 19)

At this point you can reinstall the headlights you removed or go for an upgrade. I decided to go with a pair of Valeo Cibié headlamps with Osram H4 65/70 watt halogen bulbs. Wow - No need for those driving lights after all! 

For cars like the TR4/4A/5/250/6 you might like to add some auxiliary circuits that are also fused. The Advanced Auto Wire Auxiliary Circuit kit has a mounting board of exactly the same dimensions as the Headlight Relay Kit used here. In the example shown in this installation, I mounted the headlight board on the top side of the firewall panel and the bolts went right through to include similar holes in the auxiliary mounting panel on the inside of the passenger foot well.

The low beam side of the Osram bulbs burned out after only two summers of driving with very little use. The Roadster Factory carries H4 bulbs in 55/60 watt and 55/100 watt bulbs. The Osram bulbs were replaced with the 55/100 watt versions. Most auto parts stores carry H4 bulbs but I could not find any in an appropriate size.