Courtesy lights

[Morris Montego]

I bought some new bulbs first thing this morning......but no wonder my courtesy lights were not working!! Each one wired differently, a cable hanging loose from one of them!!

The guy who last replaced the headlining must have "given up" on the job - to be polite about it!

I have a black cable, attachment/plug not surrounded by plastic. I have two cables whose 'plug' has a plastic surround, one cable red, the other red with another colour, line.

I'm assuming the earth attaches to the clip which extends from the bulb holder. Is the bi-colour cable the earth? Does it matter which way round, which clip I attach negative, positive to?

[Morris Montego]

[Doctordiesel77]

It is actually not wired the way you'd expect, as the earth is switched, so the solid purple (which may have faded to red by the sounds of it) which is a fused live feed goes to the single connector on the bulb holder, the black (permanent earth) goes to one of the connections by the switch and the purple/white wire which is switched to earth by the door switches goes to the other. Switch on the lamp in centre position, lamp off, no earth, switch to side with black wire, lamp on, switch to purple/white, lamp on when doors are open. Switches and bulb holders are prone to corrosion, so worth giving them a clean/moving them on off a few times to polish them up. The bulb being wired the opposite way round to other bulbs means that you'll need to modify things a bit if you ever fit led bulbs.... I have seen them wired up in a wide variety of 'not quite right' ways over the years! If you are going to be doing much with the electrical system you might find something like this useful https://www.ebay.co.uk/itm/407045400531. I don't know how good this particular one is, but for occasional use I don't think you'll want to spend 70 odd quid on a Fluke one, they are available with a crocodile clip on the lead, which can be useful sometimes, but the two pointy probes cover most jobs.

[Morris Montego]

A massive thank you, Sir!! I never cease to be amazed at the depth of knowledge you, the Club has - and the speed of reply!
There may be very few left on the road (100 Montegos, 200 Maestros, circa?) but MMOC makes my Montego easier to look after than my MG6, and probably most other newer cars too! Where else could you find such service?!

[Doctordiesel77]

A massive thank you, Sir!! I never cease to be amazed at the depth of knowledge you, the Club has - and the speed of reply!
There may be very few left on the road (100 Montegos, 200 Maestros, circa?) but MMOC makes my Montego easier to look after than my MG6, and probably most other newer cars too! Where else could you find such service?!

No problem, as you say there aren't many cars left, so we need to keep them going. Having spent a lot of time playing with electrical gear & looking at wiring diagrams, the Maestro/Montego wiring is fairly straightforward. The Lucas colour codes are pretty logical, unlike the German and French ones. If you haven't delved into electrical systems much it might not seem logical or straightforward and the wiring diagram might look like picture of a plate of spaghetti, but it does mean that anyone that has spent an unhealthy amount of time following wires won't need to put too much effort into helping you out . One of the cars at Locke Park got its rear wiper and boot light wired up last weekend, the owner didn't label the wires when he took it to bits & blew a few fuses while trying various combinations of the wires, the fact that his bulb was blown probably hindered his original attempts a bit as well, but it only took 10 minutes to sort out... Modern cars can be a bit of a nightmare when they get electrical gremlins, the answers given by diagnostic computers can be a bit misleading if broken wires, or previous incorrect connections are involved. I once spent a fair bit of time fixing abs sensors on an oil tanker, the computer insisted that the rh sensor had an excessive air gap, it looked ok, but I pushed it in a bit anyway....no difference, eventually I unplugged it, computer said open circuit on lh sensor....left and right had been crossed over, easily fixed, but only after realising that they were connected incorrectly!

[Morris Montego]

As is so often the case, it's not as straightforward as you hope......
Courtesy lights removed, cleaned, switched on/off numerous times. Wired up as you told me......tested. The passenger side illuminated permanently but when switched to the door open/close position, nothing.
The driver's side won't even come on permanently.

Remove, a bit more cleaning of connections. No change.

Has the "headlining man" failed to re-connect something properly behind the headlining?


I hadn't even considered the boot light. This don't work either but I assume its failure should not affect operation of door ones, even if there's been a bodge here too.

[Morris Montego]

......should I try unscrewing the "button" in the door pillar which controls the open/close illumination and inspect connections here?

[Jeff Turbo]

......should I try unscrewing the "button" in the door pillar which controls the open/close illumination and inspect connections here?

Yes that an easy removal. You should have a wire connected to each. The earth for the sunroof and internal lights run up the drivers A pillar. If one light turns on and the other doesn't, try swapping them over and trying again. The light connections to the bulb and each terminal do need to be clean

[Morris Montego]

Cheers Jeff.......I did wonder if swapping the lights about may do the trick

[Doctordiesel77]

One other thing worth checking is the interior light delay unit top left of the fusebox, if it is missing or not working it could interfere with the door switch side of it. As Jeff says both lights should be connected to the same earth, so odd that only one works..

[Morris Montego]

I had wondered about the delay function, but.....
I'm an early riser. I've already this morning, swapped the lights around as Jeff suggested. Great I thought, both now switch on permanently. I then checked the door pillar "buttons". Removed the passenger side one, gave it, the connection, a good clean. Replaced it and moved on to the driver's side. Unscrewed the "button" but no sign of the cable!
The passenger side door open/close function still ain't working either.

Still, it's all progress. I at least now have both interior lights switching on manually.

......and, in my door pocket, a small "under the bonnet" type torch and another small, powerful torch

[Morris Montego]

.......and, not that early - My watch says 8:55!

[Doctordiesel77]

The two torches sound like a useful safety net! It might be worth checking the delay unit, but looks as though you might be playing 'hunt the wire' first. It should be possible to see/feel it going into the top hinge hole if you take the fusebox cover off. The wire has a black sleeve on it at this point, so not easy to identify, other than by knowing it is the only single wire in that area. It might be dangling in amongst the fuse box, but more likely that it is still in the door pillar. If it is & you take the draughtproofing sponge out of the hinge hole, you should be able to wiggle it about & see it through the switch hole, then hook it out with a piece of thin wire. If it is hanging inside the car, you could feed a piece of stiffer wire through the holes & tape the switch wire to it then pull it back into place. fun fun fun!

[Doctordiesel77]

.......and, not that early - My watch says 8:55!

that is quite early enough for a sunday

[Morris Montego]

Thanks again tor the advice. I'll take another look.......sooner rather than later most likely - I have the MM bug in a big way!!