Plus 2 electric windows problem

[jono]

I am coming to the end of a long and comprehensive rebuild of my Plus 2.

I have completely re wired the car using a new loom. I have installed loads of earth points to the chassis and done all of the usual 'sensible to do' mods.

I have rebuilt all of the window mechanisms including new capstans and stripping and rebuilding the motors.

The windows fly up and down at great speed. BUT...when I switch on the ignition they don't work

With the ignition on when you press the switch something is happening as I can hear various accessories 'dip' (fuel pump for example). Also warning lights on the dash dim, for example the handbrake warning light.

Any suggestions where to start? I have tried hot wiring an earth direct from the chassis to the door motor chassis but this makes no difference.

Any suggestion greatly appreciated.

Jon

[billwill]

It seems that something operated from the ignition switch is taking too much current.. a short circuit? Which is then dropping the available voltage for the other accessories such as the windows?


Your friend on these issues is a multi-meter, they are really cheap nowadays. Observe the voltage at the outputs of the fuse box with the ignition off and on.


What do the headlights do, with ignition off and with ignition on?

[jono]

Bill,

I have checked the headlights and they work perfectly on low and main beam

Jon

[spridget]

Check your NU wire (brown/blue) it is connected to the Purple wire that gives the current to the windows switch.
This NU wire goes on the ignition switch, and I suspect it is not plugged on the right terminal
Franck

[el-saturn]

.............................. I sure wish I was good enough to help, BUT the earthing is fundamental for the
windows and I guess your plus to one of the switches (le or re): wires or tongues touch earth or the
insulation melted during one of your TRIALS! this electrical bs is a nightmare for most of us i reckon.

[jono]

Thanks for the suggestions - will check them out.

Spridget - if the brown/blue is connected to the wrong ignition switch terminal would this not mean that other functions would not work as well? (however, everything else does work)

As a point of order, are the windows meant to work when the ignition is switched off? (on reflection is seems odd that they should work without the ignition switched on)

Cheers

Jon

[jimj]

On my S3 the windows work whether or not the ignition is on and I believe that is correct, it`s certainly more convenient. In recent times, fears of children trapping fingers when left unattended in a parked car.......etc.
Jim

[billwill]

Thanks for the suggestions - will check them out.

Spridget - if the brown/blue is connected to the wrong ignition switch terminal would this not mean that other functions would not work as well? (however, everything else does work)

As a point of order, are the windows meant to work when the ignition is switched off? (on reflection is seems odd that they should work without the ignition switched on)

Cheers

Jon

In my S3 the windows always worked both up and down with the ignition off.

I think that modern health & safety requirements mean that windows of modern cars will OPEN with ignition off, but will not CLOSE unless ignition is on. That of course is rather more tricky to wire up and would not be straightforward to do on an Elan.


Meanwhile back to your problem, for which your symptoms are most puzzling.
Have we got the wiring diagram of the Plus 2 on this forum anywhere?

[tcsoar]

Hi Jono,

The windows are not wired through the ignition switch and should work without the ignition being on as yours do.

If they work perfectly well when the ignition is off but not when you switch the ignition on it sounds to me like something that is connected to your ignition is drawing to much power from the battery, either a faulty component or a short in the wiring. It could also be an earth problem but if you have connected a temporary earth to the motor that should disprove that, did you run the temporary earth back to the battery?

Have you tried putting a meter on the battery supply at the solenoid to see what the voltage does as you operate the windows, turn on the ignition and both at the same time?

Depending on your model, and with the aid of the electrical diagram, you could remove all the fuses except those that supply the windows. Next try the windows with the ignition on. If the windows still operate slowly or not at all then the problem is with the wiring. If they move up and down normally I would then turn off the ignition and replace one fuse and try again. Keep repeating this replacing one fuse at a time until hopefully you will replace a fuse and the symptoms reappear. This could help you narrow down what items and associated wiring that could be causing the problem.

I know this seems alot think about, unfortunately this sort of problem is not the easiest to diagnose on a forum and you really need to be there to see what is happening while testing, you are too far away from me but wonder if there is anyone local to have a look, two heads better than one and all that.

Chris.

Chris.

[billwill]

OK found one on here:
lotus-electrical-f38/circuit-diagram-for-the-plus-t19888.html

According to that the windows should only operate with ignition on or with the ign switch in the accessories position.


I think that the switches are constructed internally with an arc of metal which contacts both the accessories output contact and the ignition output contact in the ignition position. I had trouble with that on an ignition switch of mine and I suspect that if you carefully dismantle your switch you will find that the arc of metal has been burned or corroded in at the point where it connects with accessories in the IGN on position.

[spridget]

Jon,
What +2 do you have ?
The windows are wired on the headlamps loom and they must operate without even when contact is off, it is the same with the lamps
On early cars the NU wire goes from the contol box to ignition switch and the windows wire picks on. On S130 windows are fused

I have attached the wiring diagrams I have

I hope this helps
Franck

[jono]

Okay chaps, update time......

I've done some more tests and observations:

With the ignition off, the windows work but the ignition light, handbrake light and fuel low warning light come on simultaneously as the switch is operated either up or down. At the same time, there is a swing to the tacho - obviously something is feeding back through the ignition switch/circuit(?)

With the ignition switched to on, only the up mode will work (in the off mode both up and down modes work).

....thoughts on the back of an envelope please

Jon

[tcsoar]

Jon,

I have had a look at my wiring diagrams and can see at least three different ways the windows are wired depending on the model of your car, we really need to know which model you have.

Chris.

[jono]

Hi Chris,

It's a +2S 1970 model, with alternator.

Cheers

Jon

[stugilmour]

Jon, that sounds like a tricky one. You mention you added some chassis ground points during the rewire? Perhaps with assistance from a helper you can check the potential at the various grounds while operating the window switch? It sure sounds like a dodgy ground causing stuff to power up backward?

For the ignition light, handbrake light & low fuel light to come on, they have to be getting power from somewhere. Interesting that all three of these are switched to ground, and powered Hot in Run & Start. If the ignition switch is off, there should be no way for them to light up. Bit of a pain as I think they go to three separate chassis grounds; alternator to engine, brake lamp to dash bracket ground, and low fuel to the fuel tank/boot ground.

I'm with Bill thinking of the ignition switch being pouched here. Mine was bad in a different way; the ignition was not hot while the car was being cranked over. The mechanic doing final shake down took it apart and fixed it, although I knew I had an issue and had purchased a new replacement switch. Note the switch eventually went bad again and I replaced it with new and no issues.

Remember you can have two issues at once. I think I would replace (or service) the ignition switch off the hop and then recheck things?

HTH let us know how you make out.

PS Assuming looking at the diagram your windows are supposed to be powered only in Run, Start or Accy; powered by a Green wire (Hot in Run & Start - Fused). Mine ('69 Federal) are Hot at All Times and powered by Purple (Hot Always - Fused).

Edit to add a Question. Did you ground the window motors back to the dash bracket chassis ground? Just a thought here. If the ground is not solid to the chassis the motor current could be back feeding from this ground point thru the other stuff?

Stu