How is a Lotus like the Forth Road bridge?

Well I think I've said before that this car just really doesn't want to be rescued... I should have remembered that because after a couple of really positive days it reminded me with a vengance!

Moving on towards the MOT, I thought I'd better check the electrics before I declare the car ready... I hadn't expected any significant problems since sorting the electrics had been my first task... Wow almost 2 yrs ago now! However, I did suspect a current drain as the battery seems to run down. I can detect a 75 mA drain but this I think is due to the clock. It stops if fuse 3 is removed and this governs interior and boot lights, door lights and radio cassette clock.

Well I tested the electrics and found: headlights inoperative, door and interior lights inoperative (although the front interior light did work through its switch). Rear courtesy light inoperative, Hrw intermittent. Side lights working - blown bulb front lhs, boot light working. I don't think I have dash lights or fog lights and couldn't check reversing lights or brake lights on my own. Heater fans working.

I was pretty sure that I had repaired the door lights already and that the interior lights were working through the courtesy switches, but I thought I'd either taken the bulbs out or disconnected the switches to avoid running the battery down. I checked both door fittings and found both bulbs were present, I had also repaired the light fitting on the rh door. Since the bulbs were present, maybe I had disconnected the lights? I stripped the door card off the Lh door but there was no disconnection point in the loom. It seems I had mis-remembered my door light work and sadly its not shown in my blog which I was only just starting at the time. This means I have no record of exactly what I did! There is a moral there I think. However, I remain certain that the door lights had been fixed, so I was disappointed that they needed to be revisited.

Although its always possible, it did seem unlikely that both courtesy switches and door lights would fail together, so I'm assuming its something I have done since that might affect several systems. A bad or disconnected earth is an obvious candidate, especially as I had disconnected and refitted the pedal box earthing stud.

Checking the wiring diagram shows that interior and door lights should be fed from the battery via fuse 3 in a circuit that splits into two halves: One  operates the interior lights, running through the lamps to earth through their integral switches, whilst the second feeds door and interior lights to earth through the courtesy door switches. I checked for power at both door lights and found it present. To my surprise I found power to both terminals of the bulb holders (bulbs removed) and I struggled to get my head round this. I think its a power feed from the rear interior light which is also operated via the courtesy switches but I need to think about this more. If I earthed the pink/white terminal the bulb illuminated so it has to be a bad earth. I removed the dashpod again and spent a while checking and rechecking the earth connections to the pedal box. However, I couldn't find any problems; no dangling unattached wire, so I re-tested the switches... And yes... You have guessed it, against the odds both courtesy lights had failed at the same time!!! Who would guess? Just goes to prove don't shorten the usual test procedure just because you are sure it had to be something else... Although the switch had a good connection to earth through one terminal (black wire) and to power to the door light (pink/white wire) it totally failed to connect the two! If I bridged the terminals the the door light illuminated.

Courtesy lights
The usual response would be to fit a new switch. However this is a Lotus and so its not that straight forward. Firstly as there is a GRP body it needs a twin terminal (non-grounding) switch, and secondly, in this case it mounts via a threaded stem and knurled ring rather than a screw-on surface plate. Both of these features mean its unusual--- and so more expensive than I expected at £10 plus VAT and delivery each! That's likely to be £30 in total for the pair so I thought I'd try to repair them first. Luckily this did work.

The switch isn't meant to be user-serviceable, but its a simple job to drill out the two copper rivets once the knurled retaining ring and its bracing nut are removed.

Courtedy switch held in vice copper rivets one each side

... and this separates the top plate with threaded stem, bottom plate, insulating washer and switch body.

Loosening switch components

Switch components.Threaded tube, base plate and insulating washer plus switch body- still contains plunger, slotted plates and bar contact

The switch consists of two terminals which extend to form slotted metal plates. These are separated by a spring-loaded plunger.
The plunger has two wide plastic lugs which locate it in the slot in the plates and a narrower metal bar above.

Slotted plates slipped upwards to release metal contact bar. The plates pull all the way out but note that they have an indentation on the inside that has to face the plunger.

Hole through central plunger for metal bar contact.

Since the lugs are wider than the bar the bar doesn't contact the sides of the slot, however as the spring pushes the plunger up when the door is opened, the metal bar is forced to the top of the slot where it bridges between the two plates connecting them electrically.

The plates slide out easily for cleaning. The plates were corroded and dirty while both bars were worn where they contact the top of the slots. I rotated the bar to put the unworn side uppermost. I applied a smear of dielectric grease to both plates and the bar to help prevent corrosion in future and reassembled. I don't have any copper rivets to replace those I removed but they can be replaced by carefully bending a split pin.

Split pin insetted through rivet holes and bent down- it will need to be tightened either using pliers or by standing the pin's head on the anvil and tapping the tangs with a punch- care ensure the force goes through the pin not the plastic!

Split pin tightened

 This needs to be compressed to hold the top on which I did using a punch to tap the tangs down. This does work but you need to make sure that the split pin takes the force on its head or you will crack the switch. In fact even cracking isn't a disaster because the body can be easily repaired with a hot glue gun. Screwing the nut down clamped onto the end of the split pins to secure everything.

Bracing nut holds pins

Terminals clean and greased.

I reassembled and tested the switches. Both did now work and, although efficiency wasn't 100%, it was much improved and I think will become more reliable with use... I suspect it was lack of use that had caused this problem in the first place. Now that the interior light came on and off I did notice that there was no delay when the doors were closed- despite the presence of the DCR2536 delay unit relay. I removed this and cleaned its terminals- this did generate a delay but only on 3s or so- which is as much use as no delay at all. Since the forum speaks of 30s delays I suspect that this means the unit is on the way out and needs to be replaced. Whilst dealing with these relays I also noticed that the flasher frequency (direction indicators) has become quite fast. Its not too bad using only one indicator, but switching both sides on as hazard lights induces a frantic clicking as if approaching climactic release! This also needs a replacement, so I ordered an NOS unit, They are pretty ubiquitous type 19FL and I got a couple of Ford items from a liquidation stock. Swapping the unit gave a much more sedate and respectable frequency.

I also got a replacement (used) light delay unit from Lotusbits. Again easily swapped, and this is now giving a more useful 12s delay. Both relays were installed with clean contacts and DE grease to hopefully keep them that way!

Int light delay unit (yellow) and flasher unit black in relay bank behind instrument cluster.

Rear Interior light
The rear interior light was still not working. There's no description of how to remove the interior lights- but the front one has a small metal tag on one side- simply pressing this in towards the middle of the light released the latches. These appear to be Hella light units as used in the porsche mpn 2JA 002 931-031

Front light- removal tab clear to left.

However the rear light didn't have one of these and so needed to be pushed in using a screwdriver- carefully. It then popped out and the missing latch was revealed as present but hidden somehow under the headlining.  The light fitting was badly corroded and the bulb filament was broken.

Rear interior light- no obvious removal tab until dismounted. Terminals and metalwork v corroded. I had to cut the wires but this shows connections- purple to large spade, black and purple/white to small spade terminals.

The terminals were so rusty I was forced to cut the wires and release them on the bench with careful use of pliers. The light receives power through the large spade terminal and this passes through the bulb to earth; either directly or through the courtesy switch in the door depending on how the selector switch is set. I immersed the unit in DeoxC to try to clean up the various bent metal components that looked far too delicate to clean with a brush.

Rear light fitting- de-rusted and cleaned, smeared with dielectric and rewired.

The contacts cleaned up quite well so I crimped on some new terminals on the dangling wires and refitted it, smearing the metal parts with dielectric grease. Of course being a light this will warm up in use and melt the grease, but then I doubt that this particular light will be needed very much and so its more a case of preserving it against an occasional requirement. Interestingly the strange "half width" spades to which the two "earths" connect don't seem to be modern crimp, Lucas or Japanese sizes and I had a bit of trouble getting them to fit... a little persuasion with a screwdriver seemed to help and the rear courtesy light was eventually refitted and functioning through either earth! I am not convinced that it will hold though and it might be best to solder the wires on with a bullet in-line connector to the loom.

Light refitted into disgusting headlining-covered roll bar trim

I have of course refitted the light into the disgusting flaking and revolting remnants of a former headlining. -Well the headlining covered roll-bar trim anyway. This will need to be replaced when the headlining is renewed- a job which I think is beyond me. However I did notice these nasty rusty wire mesh covers on the ventilation outlets behind the roll-bar- if I can get the trim off I may well repaint these.

Rusty vent mesh in roll bar trim

Headlights
Luckily for me the problem with the headlights turned out to be more easily solved. I started by checking the fuses, and when I had removed and re-inserted fuse 5 the RHS headlamp started to respond. The LHS wouldn't raise but the LH headlamp came on.

I removed the LHS lamp and all three relays in the void behind and checked them in my relay tester- I bought a cheap Bergen copy that works very well. One relay failed but this was fixed by cleaning the contacts.

Bergen tester

Tester in use- it puts the relay through multiple cycles and generates a red/green verdict at completion.

I reinstalled all relays and... no difference! I deduced that since the pod showed some spasmodic movement and the headlamp came on, then it must be receiving power but it could possibly be out of synch with the other lamp. This had happened before when I initially sorted the lights and I think its because I had raised and lowered them manually so many times whilst I was replacing the crash panels that they got out of synchrony. Anyway I turned on the lights and the RHS pod came up. I then rotated the manual raising control underneath the LHS pod to raise it until the motor got over the dead area and took over the process. Both now respond up or down at the same time and I have a flash function too! Hopefully this is now sorted- but it probably means that I need to remove, clean and replace all fuses.

Well progress then- I still need to check the brake and reversing lights but I do expect those to work (although brake may need some adjustment).