Alternator warning light coming on but alternator charging

Technical advice Q&A

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French Collection
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Joined: Sun Aug 24, 2014 4:21 pm
Location: Aix-en-provence, France
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#1 Alternator warning light coming on but alternator charging

Post by French Collection » Sun Jun 02, 2019 6:37 pm

I have a long-running problem with the alternator on my series 1.5 E-type which recommence this weekend.
I have read the other posts on this topic but not found anything exactly like mine.

Here is a summary of the saga. Any suggestions welcome.....

Late 1967 E-type 4.2. Completely restored, bodywork by CMC. Complete new loom supplied by Barratts.
Restoration completed October 2015, covered about 2500 miles since.

New battery (old style, rubber case, lead acid), alternator (11AC uprated to 55A, Barratt’s recommended it – I did ask if there were likely to be any issues with this with standard regulator etc) and standard 4TR (3 terminals) regulator supplied by SNG Barratt June 2017.


Original symptom

Alternator warning light flashing faintly on and off. This started around November 2017.

Noticed damage to the battery clamping frame where acid from the battery had attacked the paint on the frame. I concluded that the alternator was over-charging and caused the battery acid to overflow. Voltmeter just about into the read zone at the top end. When I switched headlights or other electrical load on the flashing stopped and voltmeter dropped down to the normal zone.

Sent the alternator, regulator, and 3AW relay to SNG Barratt for testing. All ok according to Barratts.

In parallel, I had the battery tested locally. Although it was still functioning they reported at least 2 dead cells.

I refitted the alternator etc when they cam back from Barratts, and on initial test in my garage all seemed ok.

The following day I drove 50 metres from garage to the house. No problem. Switched off. 10 mins later set off in the car to take it for a test drive. Alternator warning light immediately flashing faintly on and off - exactly as before. Did a 20 min test drive. On the last 5 mins the alternator warning light came on full and stayed on.

Next morning, tried a spare regulator to see if it made any difference. It did not.

Tried a spare alternator relay. Warning light was off. So I bolted that relay on. Started the engine again and the warning light was fully on.

I found an apparent bad connection in the brown / green wire on the connection beside the big bolted one on the alternator.

I cut this wire back to where it seemed to have an internal break and added a new piece with bullet connectors. Took the car for another 15 min test drive and all was good – warning light stayed off, with no flashing and the voltmeter was reading just below the red zone (just under 15v I would say).

Ordered new alternator loom. Fitted this (about 2.5 hours work). Started the car and the warning light came on. In removing the old loom I noticed that the insulation on the termination on the brown purple wire where is connects to the alternator was burned.

Checked all the connections, relay, regulator as before. Then checked the connection of the brown / purple wire to the alternator as previous burning suggested a problem here. Pushing this terminal resulted in the warning light going off. I presume that in my previous jiggling of the wires where I thought I had found a fault, I was actually also jiggling this terminal to eliminate the bad internal connection.

Removed the alternator and contacted a local Jaguar parts supplier who suggested taking the alternator to AlStart in Marseille.

They tested the alternator, found a faulty brush which they replaced on the spot for €20.

Refitted the alternator, all seemed fine. Took the car for a 30 min test drive, all fine. Voltage at battery with engine on tick-over between 14.5 and 14.8 V. Drops to about 13.8 with headlights on and engine on tick-over.

So, it seems to me that the fault was a bad connection on the alternator.

The the problem started again...

Ken Jenkins put me in touch with Jim Brankin who supplied with with an re-built original spec alternator and a 4TR regulator which he had tested.

Fitted these and all was fine, with voltmeter usually reading around 14.5V, confirmed by my multi-meter readings on the battery.

The I noticed that the warning light took some time to go out after starting the engine - maybe 20-30 seconds. On a trip of about 200km last Thursday the light strtaed coming on intermittently, and then started staying on longer. There was no change in the voltmeter reading on the car.
When I got home I checked the battery readings with engine on and off, at tick-over and around 2000 rpm with load. All seemed fine with the charging system. Today the ligh is on nearly all the time.

Removed the Brankin alternator and re-fitted the Barratt alternator. It behaved exactly as before with flashing warning light, but all normal with headlights on.

I have interchaged the new style 3AW from Barratts, the electronic alternative from another supplier, tried various 4TR regulators and a new alternator relay.

It could be that these have all been damaged by trying with various combinations of faulty alternators.
However, when I first fitted the Brankin alternator everything was new or confirmed good, including battery.

Could there something on my car that could be causing these problems? I have checked the main earth to the body, I have re-crimped all the terminal on the alternator loom.

Heat in the engine bay cooking things? Could mine be hotter than normal? The gauge reads 90, fan comes on at that tempearature. Seems normal.

I'm taking the Brankin alternator to the local specialist tomorrow to have it tested.

Help please!

Brian
French Collection
1968 E-type 4.2 roadster
1975 XJC
1976 Triumph Stag

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christopher storey
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#2 Re: Alternator warning light coming on but alternator charging

Post by christopher storey » Mon Jun 03, 2019 11:44 am

Your car is probably about at the point where the ignition light changed from being powered by oil pressure , to being a genuine charging warning light . I should check that by chance someone has not used the old oil pressure system where the light is driven by a pressure switch on the right hand oil gallery at the level of the oil filter. That having been said, the series 2 cars are notorious for this flashing alternator light for no discernible reason

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malcolm
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Location: Fleet
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#3 Re: Alternator warning light coming on but alternator charging

Post by malcolm » Mon Jun 03, 2019 1:58 pm

If it's any consolation, my light has flashed intermittently since I've had the car (6 years) It's a 1969 series 2 2+2. Battery seems to keep charged though.
Malcolm
I only fit in a 2+2, so got one!
1969 Series 2 2+2
2009 Jaguar XF-S
2015 F Type V6 S

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johnetype
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#4 Re: Alternator warning light coming on but alternator charging

Post by johnetype » Mon Jun 03, 2019 7:57 pm

You may be aware of this but it's important to understand that the ignition warning light on the 4TR regulator and alternator system does not function the way a modern day ignition warning light does.

The ignition warning light being on or off or even fitted at all has no influence over the working of the alternator or 4TR regulator hence why through all your investigations you've had 14.5 volts or so across your battery and a normally charged battery to boot.

The original 3AW is simply a thermal switch that grounds the ignition warning light turning it on as a result of around 8 volts AC being present on its unique connection to the alternator. Those 3AWs were fragile and prone to faulty indications. There are now aftermarket electronic 3AWs available but User experience would suggest they are prone to illuminating the warning light dimly when there's no charging problems.

Although it is possible to have a faulty alternator indicated by a properly working 3AW it's highly unlikely and given you've tried two alternators and they both output around 14.5 volts under control by the 4TR I'd say your only problem is with the 3AW itself and based on Malcolm's experience it may be one of those just live with it issues until a new electronic 3AW becomes available that doesn't cause some flickering.
John

1969 Series 2 FHC

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Topic author
French Collection
Posts: 20
Joined: Sun Aug 24, 2014 4:21 pm
Location: Aix-en-provence, France
Ireland

#5 Re: Alternator warning light coming on but alternator charging

Post by French Collection » Wed Jun 05, 2019 6:55 pm

Thanks for the comments and suggestions.

I have checked that there is no link to the oil pressure warning.

In the meantime I think I found the problem Monday night by fiddling around with all the wires.

There are 2 brown / purple wires crimped together into a single spade connector that connects to the alternator relay.

Its seems that there was a poor / intermittent connection between the wires and the connector - probably because of the 2 wires. By jiggling this I was able to make the warning light flash or stay off. I have now soldered the connection and the light has stayed off. Only tested it with one of my alternators so far :bigrin:
I will try the other one and do a proper test drive over the weekend.

Interesting that I had exactly the same problem with the first alternator loom. Passed the feedback to Autosparks.

Malcolm, this might be the source of your flashing light also. the relay is on the mud-shield in front of the battery. The horn relay is just below it.

Brian
French Collection
1968 E-type 4.2 roadster
1975 XJC
1976 Triumph Stag

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