Project Defender Td5, part 10: Dashboard wiring and new instruments

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In this part 10, Trevor gets out the crimpers : credit: © Trevor Cuthbert
Trevor gets the Defender wired for the future and installs a tasty new instrument panel

Need to know

Time: 9 hours.
Cost: See below.
Difficulty: 3 out of 5
Models: Defender 90, 110, 130.
Tools needed: Drill, side cutters, spanners and socket wrenches, sharp craft knife, general workshop tools, square files.
Parts & costs: Defender binnacle mount, £44.50, from Raptor Engineering Ltd; 7-core cabling, 25amp cabling, speaker cabling, £15, from CJ Collins Electrics; Defender binnacle, £92.50, from Raptor Engineering Ltd; aluminium switch plate, £7.20, from Raptor Engineering Ltd; speedometer light bulb x2, 509T, £1 each, from Halfords.
Work safely:
• Disconnect the battery before
work begins.
• Ensure cables are secure and protected from sharp objects.
• Have your work checked by a professional if you have any doubts.
Contacts: Raptor Engineering Ltd, Tel: 07503 122 223. raptor-engineering.co.uk

See also, Project Defender Td5, parts 1-9 here.

A Defender dash and general interior is not the most difficult of vehicle environments in which to run additional electrical circuits and conceal the cables, especially compared with modern cars and trucks. Modern vehicles have dashboards and interior trim that feel like they are sealed for life and don’t invite aftermarket wiring, not to mention the implications of interfering with bespoke vehicle electrical systems. In comparison, we can easily add electrical accessories for essential jobs (or to customise our Land Rover to personal tastes) without fear of causing expensive damage to the vehicle interior or its electrical universe. But we still need to follow good wiring practice in terms of using correct fuses, relays and cable protection. However, always have your work checked by a qualified auto electrical technician if you have any doubts.

Building to a plan

While it is relatively easy to add cabling to a complete and intact Defender, there is no better opportunity to plan and install cables when the vehicle is at this stage of build up. While I am reinstating the factory wiring harnesses, dashboard and engine bay components on the freshly prepared bulkhead, I’ll establish additional circuits to facilitate new components and potential future additions that I might decide to fit.

Right now, the list of extras I plan to install include: flashing beacons on the roof, front and rear work lights (LED), on-board air compressor, tachometer, cruise control, 4-speaker audio system, extra marker lights and daytime running lights (DRLs).

To enable all these components and future expansion, I will run cabling from the ECU compartment to the dashboard, also from the battery compartment to dashboard, and from all three locations to the engine bay. The cabling will be a mix of grades that can carry significant current say, to power the air compressor, plus light grades that will simply trigger a relay or send signal to the tachometer.

Back in place: The main electrical wiring harness for the bulkhead is first to be fitted in place, closely followed by the windscreen wiper wheel boxes with tubes assembly.

Utilising existing holes: The washer jet is also fitted early in the process or, in this case, two washer jets, which is a successful upgrade I have carried out on a few lately.

Before they’re in the dash: It is a good idea to fit the wiper motor with its operating cable at this stage to ensure the cable runs smoothly through the wiper wheel boxes.

Restoring the correct size: There are three different types of plastic lock nuts that need to be fitted to square holes in the bulkhead. Here excess paint and zinc is filed out.

Ideally a snug fit: With the square hole prepared, the lock nut is pushed into place. Some need a tap with a small hammer to help get them home.

Needs to be replaced: The original lower dash from the Td5 110 had an unusual area of hidden rust on the inside of the driver’s side. Luckily a better example was to hand.

Lower dash: The replacement lower dash is fitted in position by a series of self-tapper screws into the lock nuts, plus a pair of M5 bolts at the top edge.

Letting the side down: This plastic binnacle end panel is very old and shabby looking and a replacement will need to be sourced to house the heater controls.

Old and brittle: The mounting that the instrument binnacle fits onto is also in poor condition. The sides are cracked with age and the mounting tabs broken off.

Don’t lose the screws: The fan control switch is loosened from the binnacle mount by removing two set screws that hold it on the inside left of the mount.

Off with the old: The fixings (mainly self-tapping screws) that hold the old binnacle mount to the inner dash panel are now removed to free up the broken part.

Stronger, better: The replacement binnacle mount by Raptor Engineering Ltd is manufactured from steel and beautifully powder-coated. It will last a long time.

Onto the inner dash panel: The new binnacle mount is fitted in much the same way as the removal of the old one, but requires fewer screws because of its inherent strength.

 

Provision for electrical accessories

There’s a lot going on in the dashboard, over and above the factory fitted systems, so some form of centre dash unit will need to be fitted. For this reason, cabling will run from the centre of the dash to the dash top, needing access through the plastic trim panel.

For now, the priority is to select the most appropriate cabling and plan the routing, as well as ensuring that everything is safe and secure. A dash console solution will be decided upon later.

Planning well ahead: This seven-core electrical cable is being routed from behind the instrument panel area to the ECU compartment under the driver’s seat.

Method to the mess: Additional wiring consists of speaker cable, cabling from battery compartment to dash, air compressor wiring harness and ignition feed to dash centre.

Centre dash console: Much of the extra cabling that has been put in place runs to the centre of the dash, so the plastic trim panel is cut for cable access.

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Try to remember: There is a knack to getting the plastic trim panel into position, which is a reversal of the movement and action needed to remove it in the first place.

Firmly fixed: The inner plastic trim has been secured by a series of large self-tapping screws to reduce squeaks and rattles in the finished vehicle.

Designed for extra circuits: The seven-core cable will enter the ECU compartment with the main harness, so one of the grommet blanks is snipped off here with side cutters.

Making a point: The cable is cut at an angle to easily thread through the grommet. It’s intentionally a snug fit in the cut-off blank to prevent water ingress.

Away from the propshaft: The seven-core cable needs to be secured at the top of the chassis rail. It is quite light, so there is no problem with attaching it to the fuel lines.

Away from the exhaust: On the left side, the additional cables routed to the battery compartment area need to be similarly secured, this time to the main battery cable.

 

Replacing the instrument panel

Having been manufactured in 2001, this Defender isn’t the oldest one around. However, the truck has been worked hard and, like the binnacle mount that has just been replaced, the instrument binnacle itself and the binnacle end panel and other plastics in the interior have become brittle and cracked.

Having used the Raptor Engineering binnacle mount, I decided on its matching instrument binnacle too. It is available with a black trim finish, but I opted for the aluminium trimmed version, offering a pleasing bright finish.

Seen better day: Just like the old binnacle mount, the instrument binnacle is cracked in places and mounting tabs have broken off and it is altogether shabby in appearance.

Improved over earlier: On the Td5 Defender, the wiring harness is very logical and easy to deal with, because of the use of multi-plugs instead of bullet connectors and terminals.

A minute or two’s work: The components from the old instrument binnacle are quickly and easily removed, taking care to keep things in the correct order. They need a good clean.

A fraction of the price: It is a good time to replace faulty dash bulbs and, indeed, tired ones that still work. These aftermarket speedometer bulbs are a fraction the price of OEM.

New steel binnacle: The Td5 warning lights panel attaches to the new Raptor Engineering binnacle in a slightly different way to the original, but the instructions are clear.

Screw it all together: With the plastic warning lights housing fixed to the Raptor binnacle, the circuit board and cover are now fitted at the back of the binnacle.

Pristine: After all of the parts were cleaned, the instruments and wiring harness have been fitted to the new binnacle and the finished unit looks absolutely excellent.

New fixings included: The new binnacle is now fitted to the Raptor binnacle mount using new nut plates and pan-head set-screws, giving a very positive and secure fit.

Tired old plastic: The shabby binnacle end panel, which houses the heater controls, is to be replaced by a new product from Raptor Engineering – a powder-coated steel panel.

Stronger fixing: Interestingly, the new binnacle end panel utilises this unused captive nut plate in the dash top – provided for the grab handle on left-hand drive Defender models.

Assembly begins: The heater controls are loosely fitted to the new Raptor binnacle end panel, using new screws provided. All fixings are kept loose until everything is in place.

Properly engineered: The new binnacle end panel houses the heater controls perfectly and looks totally in keeping with the new instrument panel. A fantastic result.

A nice touch: I also ordered this aluminium switch plate to match the instrument panel, replacing the broken plastic one. An inexpensive and very effective solution.

 

In the next part of Trevor's Defender project, a centre dash console needs to be selected and installed to complete the dashboard and to house the additional electrical components. With an intact dashboard and wiring, only the cooling system prevents the start-up of the Td5 engine. The coolant hoses from the old Defender engine are available, though many are soft and perished, so I will replace them with new ones, plus a new radiator and intercooler. The turbocharger also needs to be fitted and then the Defender’s engine can be fired up for the first time.

 

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