Lotus Elan

Electrics

PostPost by: TonyJ » Thu Aug 13, 2009 11:05 pm

I'm trying to get my electrics working but am getting no where! Rebuilt my plus 2 and I'm so nearly finished after a considerable amount of time! Need help :cry:

Got the hazards and dip working, as they are not on a fused circuit, only for them to stop when I connected the side lights. Can't get them to work at all now! Fed up! Can't even get the clock or interior lights to work! Thought I could understand electrics but this has me confused :? . Any ideas of why they've stopped working? Anyone in the Sevenoaks, Kent area who can help?

No idea what size fuses go in the four fuses in the dash - looked in all my info - anyone help? It's amazing how the simple things can't be found!

Tony
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PostPost by: jeff jackson » Fri Aug 14, 2009 1:38 pm

Hi Tony,
Don't despair! If it's any consolation, Lotus tested the employees who put all the wiring into their cars in the seventies and found a considerable number of them were colour blind. That's why the circuit diagrams don't always follow what's in your car.
Let me know what model plus 2 you have and I'll look at my circuit diagrams and see if I can help. If your car is a 72+2 s/130/5 you may be in luck, as that's what I have, and can look directly at my car.

Kind regards
Jeff
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PostPost by: RichC » Fri Aug 14, 2009 2:10 pm

similar situation a few weeks ago ...but at leasy mine was an early +2 with a fewer wires to contend with
when you think you've cleaned up the fuse holders and tightened up all connectors go back and clean & tighten 'em again.
follow the rule of doing the simplest stuff first . once you've disturbed & manhandled the wiring it is easy for a connector to be dislodged accidentally .
You'll get there in the end ... & then you can have a laugh over it with your mates and a few beers.
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PostPost by: 69S4 » Fri Aug 14, 2009 6:17 pm

Hi Tony

Believe me, I can feel your pain :( . I spent half of April and most of May trying to sort out similar problems on my two seater. Ultimately most of it came down to bad earths (3/4 of probs) and rusty bullet connectors (most of the rest) plus one or two broken wires / soldered joints. Even when I thought I'd sorted out all of the earths, I hadn't. Some of the newly remade earths were not earthing enough and the current was finding its own path back - usually through another circuit, leading to the sort of problem you describe.

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PostPost by: TonyJ » Fri Aug 14, 2009 7:18 pm

Thanks for the support, very much appreciated :D .

I've got a +2s130/5. Would appreciate a look at yours, thanks.

Been looking at wiring diagrams 'til my eyes start seeing the lines move! Checked continuity of all circuits according to diagram and as far as I can tell I've wired things correct. New looms used.

Got continuity through the system, including earths - not saying the earth's are brilliant as I know that a loaded earth may not be as good - but I don't know how to check this! I get 12V until I switch lights on then get nowt! Same for the hazards, I get 12V to the hazard flasher and the yellow/red coming out but when I turn it on I get OV. Brain has now stopped working :roll: and I have no idea of what this could mean? Is it a short or bad earth?

Tony
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PostPost by: RichC » Fri Aug 14, 2009 8:08 pm

dirty contacts in the switches? try switch cleaner
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PostPost by: paddy » Fri Aug 14, 2009 10:53 pm

I don't have a specific idea of what the problem is, but it sounds like some fundamentally bad connection somewhere which is creating a large resistance in the circuit. This will not necessarily be observable if you are just checking for voltages at various places because, in a circuit with no current, there will be no voltage drop.

Does your meter allow you to measure resistance (ohms)? I would check the resistance of various earths.

Also, do you know the condition of the battery? Doube-check the battery terminal connections, and check the battery is fine by connecting a high power item (headlamp, say) directly to the battery terminals.

What's the charging circuit? (ie generator or alternator)? If generator, do you know that the control box, and the control box wiring is OK? If possible disconnect the wiring relating to the charging circuit, and just test everything with a fully charged battery, in case there is someting going wrong there. It will also eliminate the possibility that you've got a +ve earth loom on a -ve earth car or vice versa.

Then, test the simplest possible circuit, with as many bulbs removed or disconnected as possible. Also remove the hazard flasher if you suspect this. Say test the sidelights to begin with, then the headlamps. Avoid anything with a flasher unit to begin with because it makes things harder to measure. With the sidelights on, and then the headlamps on, measure the voltage drop from the battery +ve to the +ve terminal of the actual bulb, and similarly the voltage drop from the earth side of the lamp and the -ve of the battery. (I'm assuming you have -ve earth.) The voltage drops should be negligible (substantially less than 1v each), with virtually all the voltage drop across the lamp.

Hopefully this way you will either find a problem, or confirm that the basic wiring and distribution is OK. Now to the circuits that depend on the ignition (stop lamps, say, and the ignition itself).

Only put the bulbs back in to the circuits you're about to test. Each time you put a bulb in, and test the circuit, re-test everything else with that new circuit turned on. This might identify a circuit that is shorting.

Report back if you find anything :)

Paddy
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PostPost by: bob_rich » Sat Aug 15, 2009 7:39 am

Hi Tony

I am rebuilding a +2S130 so I guess I will have to go through the pain U are going through as well!

regarding earths if you want to see how "good" they are and as you seem to have a volt meter the following may help. Get a long length of wire 2 or 3 metres and connect from the battery -ve to the meter -ve. Then switch on the accessory U suspect and touch the +ve of the DVM on the actual earth or body of the accessory. If earth is good then voltage drop will be very low only around less than 1.0V. If it is higher them suspect that the earth is poor. I have checked the +2 manual and cannot find the values of the fuses for the 4 in the dash. Fuses should be selected to protect the wire in the event of a short rather than selected on the current drawn by the accessory(s) on the line.

Hope this helps best of luck

Bob
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PostPost by: jeff jackson » Sat Aug 15, 2009 11:51 am

Hi All,
my four fuses are all 35A. That does not mean thats what they were when it was new. It's what is in there now.
Should make certain these values are correct I suppose!

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PostPost by: john.p.clegg » Sat Aug 15, 2009 12:15 pm

Tony

Would help if you posted your location as practical help could be better than over the forum?

John :wink:
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PostPost by: TonyJ » Sat Aug 15, 2009 9:34 pm

Location is Sevenoaks in Kent. Practical help would be great!

Thanks for all the help. I shall try the suggested ideas and hopeful be successful!

Tony
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PostPost by: bob_rich » Sun Aug 16, 2009 8:20 am

Hi Tony

I checked the fuses in my January 1974 Elan +2S130 and the actual fuse bodies are are marked as follows reading from left 2 right as you sit in the drivers seat. Only had the car since may 2009 when started the rebuild and previous owner for last 20 years did not have any major electrical problems ( that would damage wiring that is).

Cant find anything in the lotus prats list or the service manual that gives recommended value.

10A continuous 17A blow
25A
17A continuous 35A blow
25A

Hope this helps If You find anything else out please post it as I do like to get fusing (and wire ratings) correct on electrical circuits.

Best of lck

Bob


AS far as I can tell my wirIng looks like post body number 72050732L non federal
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