Interior dome light conversion under rear shelf to twin units

[Chris_Von_Bron]

http://i93.photobucket.com/albums/l55/Chris_Von_Bron/UIJ%20197/interiorlightincrease2.jpg

I’m looking to change the illumination of my rear shelf to twin dome lights.
Currently the car is stock is this area i.e. the original dimming circuit still works as it did in 1981 so not as smoothly as:-

http://www.deloreancarprojects.com/McKeenprods/McKeentimer.html

http://mysite.verizon.net/vze109dmk/
http://mysite.verizon.net/vze109dmk/sitebuildercontent/sitebuilderfiles/dome_light_instructions_080209.pdf

Any issues with this being used for the three dome lights planned below?

I have 2x door switches on the drivers side and a single on the passenger. A Clifford Alarm system has been fitted so the door switches still perform as they should but the PDF above states the custom module may not work if an alarm has been fitted so can you please confirm what do I need to check before ordering (as per paragraph 2 of page 2 of the above PDF) so when fitted I have the following benefits:-
• Superior dimming
• Programmable off override of my three interior dome lights

The festoon bulbs on the interior are 12V 7W. Is the optimum wattage? The interior lamp in the luggage compartment is 10W (a longer festoon bulb too). This part of the circuit is still running a 10AMP fuse, Incidentally I have an LED festoon in the engine compartment but would like to stick with incandescent bulbs for the interior.

I found some wire that was the same thickness of the stock harness but the spec was:-
12 strands of 0.3mm with a surface area of 2.4mm
17 strands of 0.2mm with a surface area of 3.4mm

As you can see from the diagram I’m looking to not disturb the original harness for the single dome light and looking to branch off as illustrated unless there is a better way of achieving the same end result?

1) what gauge of wire do I need (the length will be around 1 foot in either direction of the OEM location)?
2) what wattage should the festoons be?
3) will the fuse on this circuit need changing to a higher amperage?
4) Will the custom module above work based on the alarm and above circuit changes?

I've emailed David about his delay timer unit and hoping he'll also chime in.

Thanks in advance for any feedback

[Bitsyncmaster]

The added lights will not cause any problems. My unit should be good up to 10 amps. The alarm may cause problems if it's using the door switch on the light circuit. If it draws to much current on the alarm my dome unit may never think the door has closed.

If you can run the alarm on the second switch for the buzzer that would work.

I also have that extra pin on my dome unit that should provide the signal to your alarm. That pin will have the same logic function as either door open will provide a ground signal. That pin is a low power driver so you can not drive a heavy load but most alarms will not draw much on that input signal.

[WelmoedJ]

Chris,

About your alarmsystem by Clifford: I also have the Clifford 650 system AND Dave's dome light delay timer.
No problems ever met in the 3 years of use.

Wiring? Modern car wiring has lead of 50~75 mm2. I often use old computer leads from the power supply unit. Up to now never found them to be underrated.

Doubling parcel tray lights? Just connect them parallel and it will work (I've done that with the engine bay lights using double insulated cable for home appliances (like lamps) with 75 mm2 leads.

Hope this helps.

[Bitsyncmaster]

Missed your question about wire gauge and fuse. I normaly use 16 AWG wire since it fits most crimp terminals the best. Choosing wire gauge for high power circuits is more a choice of how much voltage drop you can accept. A long wire with a 20 amp load would drop a volt or more if you use 16 AWG or higher. So in that case you would want 14 or 12 AWG.

Power (watts) is equall to the current (amps) times the voltage (volts). So if you have 120 watts of bulbs, you would be drawing 10 amps at 12 volts. Stock bulbs, six 5 watt door lights, and four 7 watt festoon bulbs, plus the glove box would be about 60 watts or 5 amps if all were on at the same time.

[Chris_Von_Bron]

Based on the above I decided to go for one of Dave's units and was about to order when a owner who'd just sold his car had one unused.

The interior units were/are running 7W bulbs so for the third I've matched the wattage. Incidentally I changed the bulbs in the gullwing courtesy lights to LED's years ago which are less of a drain on the whole circuit but even with originals plus the additional 7W/third interior light I'm still within the circuit's tolerances.

I've sourced the wire UK equivalent of AWG16, have my third interior unit from my local Renault dealer and have now created the new harness that plugs into the original harness i.e. it can return to stock in the future if needed. After lots of soldering, crimping I tested over the weekend and works a treat. The OEM dimming circuit becomes less effective based on how many of the interior lights are i.e. with all three on they all go off with no delay with the door closed. The new programmable module will sort that and improve the brightness too.

The reason for the twin rear lights will become clearer once the next part of the project progresses...... ;)

[Farrar]

The reason for the twin rear lights will become clearer once the next part of the project progresses...... ;)

Too much suspense!