Flicking ammeter

Phil Robson

Well-Known Member
My 1971 3500S' ammeter constantly flicks wildly & the ignition warning light never goes out, despite the battery charging well. It's been like this for around a year. Electrics are my absolute weak point with my P6s, so I tried a couple of garages who both say they can't find anything wrong.

A friend of mine suggested I tried the 'control box' (?) out of my 1970 series 1 V8 but I don't want to damage it.

This is the alternator:

IMG_6462.JPG

This is the 3500S' box (it almost looks scorched):

IMG_6460.JPG

...& this is the other car's:

IMG_6461.JPG

I'm foxed straight away as one has 3 connections & the other has 4! Please help..!
 
There are 4 wires going to each regulator, the only difference is the Lucas one has two separate terminals for the two wires connected to positive (+). On the other, the two wires are connected together to one single positive (+) terminal. I suspect the Lucas one, has internally, the two plus terminals connected together and means the current is shared. Looking at the 11AC wiring diagram the two plus wires carry the current from the alternator to the rest of the vehicle .
 
As it has shared terminals Roverp480 do you think it might have caused the smoking affect?
That is an instant BBQ on wheels, it says made in Germany so I am guessing this control box was fitted from another car?
 
If it were mine I think I would take off the box and clean the tabs up, then as there is adequate length on the loom, remove the terminals from the leads and solder on some new ones. Those terminals could have verdigris inside them and be making a poor contact.
 
I agree with cobraboy. Especially the connection with the two wires to the plus terminal look very poorly made and is not as original. If the two wires don't connect well it will heat up as it is carrying all the current from the alternator.
 
You can see that originally the wiring was like the second photo, but when faced with the three terminal arrangement they extracted the leads fromthe black connecter and then joined the two + leads together. If it were me, I'd fit new connectors to all four wires.

Yours
Vern
 
Hi!

I had the same flickering ammeter needle and flickering lights about 25 years ago. I bought a new regulator and also overhauled the alternator but it did not help.
But the LUCAS-service man (who overhauled the alternator) gave me the right advice. As you can see in the picture, he mounted a relay for the voltage feeding to the main plus terminal (the blue cable in the picture). The fault was voltage drop from the (brown/blue) cable from the ignition lock. An easy test would be to, temporary, connect a plus cable from, for example, the terminal post under the front carpet (my car is a 1972 LHD) or from any other solid source.

I have also experienced a constant ignition warning light. This was cured by buying a new ignition warning light relay as shown in the lower right corner of the picture.

Best Regards:

Göran Olsson (Rover Club of Sweden)

IMG_0938.JPG
 
Many thanks Göran, I might try those angles. However, I have a much more pressing matter this afternoon :confused:.

I’ve changed the vacuum advance on the distributor for which I took the distributor out. When I put it back (at a pretty similar orientation I thought - the shaft located in the peg ok) I couldn’t get it to fire up. I can check the timing alright but the rev counter went wild then ALL the electrics died :oops:

I’ve checked all the fuses which are all ok.....
 
The electric failure is a flat battery, although I’m a little sceptical that it’s just a co-incidence.

Some further checks to do...
 
This evening I tried again. Forgetting the distributor problems for now, I charged the battery up to 13.45V. I could initially operate the radio, heater & panel lights etc. However, when trying to turn the engine over the starter wouldn't even make a noise & the panel lights etc have gone out. Only the map light will come on now & even this only works when the ignition is off. The battery is still at 13.35V.

The ignition switch has always been a bit of a fiddle on this car; might that be the culprit?

TBH I'm a bit overwhelmed with such a total failure, when I was only trying to change the distributor vacuum unit! :confused:
 
Hi, there's a bad connection somewhere that will pass a low current but will collapse when there's a high one. So it's a case of going round and checking and cleaning them all from the battery all the way round and back to the battery again, which means earths as well.

Colin
 
Had exactly these symptoms on my old land rover , everything worked until I operated the starter., then dead It was in my case a bad battery connection, so I would be looking as others have said , to all the connections of the battery and starter cables , both ends of each cable and indeed the integrity of the eyelets etc.. Just tightening is not sufficient, they need taking of and cleaning the faces before assembly again.
 
Thank-you for your suggestions guys.

I have now had the starter terminal connections off & fully cleaned & refitted. The battery terminals are excellent too. The battery post connector in the driver's footwell is clean & tight but I haven't as yet had it apart because it seems to be sealed, but may have to as a last resort.

I can't believe it's a co-incidence that I'd taken the distributor out & replaced it, then this happens. I'm only trying to turn the engine on the starter with none of the ignition circuit connected so as to remove the chance of any problems there.

As previously noted, the ignition switch has always been a bit iffy & I wonder if this is what the problem is? The radio does flicker when I turn the key (even when it's off) but also when I turn the light switch on above it.
 
The electric failure is a flat battery, although I’m a little sceptical that it’s just a co-incidence.

Some further checks to do...

Seeing Hazel is temporarily laid up, I had another think about BOP & decided to replace the battery with a good spare. Unbelievably it turns the engine easily :) so I can only assume the one I bought under 2 years ago is not holding its charge.

How many times have I posted on here “try the simple things first”...?

I now need to get the timing sorted so will go 'by the book' tomorrow starting from scratch. Of course I won't be able to check the dwell angle just yet because I destroyed the meter when timing Hazel :rolleyes:
 
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