S2 Electrical problems

DazbodS2 · Post by **DazbodS2** » Fri Dec 11, 2015 10:31 pm

Hi All, this is my first post having recently purchased a restored S2 coupe. Looking for some advice. Whilst connecting a trickle charger live clamp, to the battery I can only assume I shorted the lead to ground as an arc was induced although I can't see how. On subsequently turning on the ignition the car starts and runs but the blue non charge light is now on and the Rev counter is dead, all other electrics seem ok. I have replaced the 4TR control box to no avail. I guess I will have to get the alternator checked in case the diodes are fried but not sure where to go with the tachometer. Have studied the circuit diagram and cannot work out what could have happened especially as the ignition switch was open.
Any thoughts would be appreciated.

chrisvine · Post by **chrisvine** » Sat Dec 12, 2015 12:06 am

I believe the internal electrics for the tachometer are powered from the green feed from fuse 7 and the circuit is detecting the pulses of current flowing in the tacho's white wires to supply the coil.

Have you checked that fuse 7 has not blown? It should be easy to do as it supplies the voltage regulator to the fuel and water temp instrument gauges and wiper motor. If the fuse is ok, I suspect it might be something internal with the tacho since, as the car is running, the supply to the coil going through the tacho doesn't appear to be an issue.

For the not charging warning light, you mention the blue tell-tale light (main beam indicator light). Do you mean the red ignition warning light?

Chris

DazbodS2 · Post by **DazbodS2** » Sat Dec 12, 2015 10:06 am

Hi Chris many thanks for your response. I did mean red ignition lamp not blue apologies. I did indeed check fuse 7 but that seems OK. I did notice today that I get an occasional small blip on the tachometer but otherwise dead as the proverbial Dodo. My first priority is to get the charging circuitry sorted so will get the alternator tested first. I did note in the manuals it refers to a spring loaded jockey wheel assembly used to tension the belt which my car doesn't seem to have!

Post by **mgcjag** » Sat Dec 12, 2015 10:12 am

Hi ..Whats your name......what does the volt merer reading show.....re the fuse, clean the springs where the fuse plugs in and the fuse ends very common for them to have bad contact

DazbodS2 · Post by **DazbodS2** » Sat Dec 12, 2015 11:24 am

Hi Steve Thanks for the advice I will give it a go. All other Fuse 7 circuits appear ok though but worth a try.

I'd forgotten all about the joy of Classic car ownership. fix one niggle and create another 3!

DazbodS2 · Post by **DazbodS2** » Sat Dec 12, 2015 11:27 am

oh the names Darren.

christopher storey · Post by **christopher storey** » Sat Dec 12, 2015 11:28 am

If you are getting an intermittent flicker from the tacho, it is likely that it is not earthed properly . You need to clean and tighten up the various points of contact with the earthed bodywork, which is a bit of a job since the easiest way to do this is to take the dash top off, unless you can reach it from underneath which is sometimes but not always the case , to grab the instrument body and rotate it a few times against the metalwork of the dash .

Don't worry about the jockey pulley, they are often taken off , and serve no real useful purpose except to make changing belts easier. Incidentally, don't rely on the fuse numbers - over the years the cars are often rewired with different fuses being used , so try the fuses which have green supply and feed wires

DazbodS2 · Post by **DazbodS2** » Sun Dec 13, 2015 8:02 am

Thanks for the reply Chris. Have had a play around but still no joy with the tachometer, will try again today. To answer Steve's earlier question ref battery voltage. I took the following readings across the battery terminals with a fully charged battery. 13v ignition off dropping to 12.65v with the engine running. The dash voltmeter is bang on the normal line. I ran the car for about10 mins with only a slight reduction in terminal voltage. The car has had a fairly extensive restoration but although the loom has been rebound the wiring is original and shows signs of its 45 years. I will get the alternator off and get it checked by local specialist although they say the diodes are no longer replaceable and some other form of rectification is used. The alternator is a Lucas 60 amp with front mounted external fan. Not sure if that's original but it's a nice unit and I would rather have it repaired if it is faulty than use a modern replacement. On a related but separate matter I have seen a colour coded more detailed version of the S2 circuit diagram on the net but it is low res. Is this obtainable in large format?

Gfhug · Post by **Gfhug** » Sun Dec 13, 2015 9:40 am

Have you looked at the one in the knowledge section?

http://dl.dropbox.com/u/8496016/Late%20 ... Colour.jpg

christopher storey · Post by **christopher storey** » Sun Dec 13, 2015 4:03 pm

Dazbod. Since you have a voltmeter there is no need to remove the alternator to test it. Put the headlights and some extra load like heater fan on . Then measure your battery voltage - it will probably be something like 11 volts . Now start the engine and run at a fast idle with the electrical load still applied at - say- 1000 rpm. Measure the voltage after say 15 seconds and 30 seconds. If the alternator is working properly it should now have risen to c. 13 volts

DazbodS2 · Post by **DazbodS2** » Sun Dec 13, 2015 10:14 pm

Gfhug many thanks that's the one. I think I will get it printed A0 size and wallpaper my garage with it as I think the way things are going i'll be using it rather a lot

DazbodS2 · Post by **DazbodS2** » Sun Dec 13, 2015 10:23 pm

Chris - many thanks I had hoped that a straightforward test was possible in situ, will get my AVO out and see what's going on.

DazbodS2 · Post by **DazbodS2** » Wed Dec 16, 2015 9:21 pm

Hi Guys - Ref Gfhugs earlier post Directing me to Dropbox I note the circuit diagram reference to "1970 E Type ballast ignition". Is this a specific mod to models made in1970 (the year of my car) If so why the mod?

Gfhug · Post by **Gfhug** » Wed Dec 16, 2015 9:47 pm

Here is an explanation of ballast ignition http://www.accuspark.co.uk/faqs.html#q1

If you search the forum you will see some references to them also.
Hope this helps

Geoff

DazbodS2 · Post by **DazbodS2** » Wed Dec 16, 2015 10:28 pm

Thank again for your help Geoff - this might explain why I have an extra lead on the coil!

wol916 · Post by **wol916** » Thu Dec 17, 2015 2:44 am

I had the same symptoms recently, it was the alternator relay on the back of the inner wheel arch next to the horn relay it was sticking, just pulled the top off and gave it a clean all sorted. Easy to test just pull the wires off and plug onto a spare relay (modern plastic one will do).

DazbodS2 · Post by **DazbodS2** » Fri Dec 18, 2015 5:31 am

Thanks Waren was going to take off the alternator this weekend and get it tested. I will check the relay out as you suggest first. I'm not sure how easy removing the alternator would be as there appears to be very little space between the alternator casing and the engine to free up the belt.

DazbodS2 · Post by **DazbodS2** » Fri Dec 18, 2015 8:32 am

Hi again Warren - I seem to have two similar relays one above the other behind the near side inner wheel arch not sure which is the Alternator relay

Post by **mgcjag** » Fri Dec 18, 2015 9:41 am

Alternator is really easy to remove compared to most jobs on the E....once removed well worth checking the brushes yourself....where the wireing plugs in remove the small connector unit you will probably find well worn brushes....the plastic replacement and brushes can be got from sng..horn relay has purple wires ....alt relay has large brown and large white wire

wol916 · Post by **wol916** » Fri Dec 18, 2015 8:26 pm

On my car the alternator relay is the bottom one the other is for the horn.

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