Pulsing Lights - Alternator Rectifier?

[Marty V8]

Hi,
All the lights - interior, dash warning, headlights have started pulsing when the engine is running. The pulse rate doesnt seem to increase with an increase in revs.

I suspect the alternator rectifier is on its way out.

Does anyone have any other suggestions/experiences and advice as to where I may possibly get a rectifier for a Griff 500 serp?

Off to trawl through the TVR parts suppliers websites now....

Cheers

Marty

[Marty V8]

Thought I would bump this.

Can anyone help please?

Thanks

Marty

[Rob_the_Sparky]

Not heard of it before but it does sound like you are getting a voltage variation so rectifier certainly sounds likely. You could put a DVM on it and see what is actually happening - I'm assuming the pulsing is fairly slow though, too fast and a DVM will not pick it up.

[Podie]

I had a similar issue with a Mondeo V6 a few years back, and eventually found this resolved it. It may be of use?

TSB 053/2001

[i]Summary

Should a customer express concern about flickering headlamps, wavering illumination of the instrument cluster, interior lighting and audio unit the probable cause is an extremely high resistance in the battery wiring harness from the central junction box (under the bonnet) to the B+ terminal on the alternator. To rectify the concern an additional cable should be installed.

Part number for this cable - 1133503 [/i]


Apparently the high resistance from the 7.5A fuse to the alternator multi plug causes it to "pulse" so the new loom does away with this by taking a new feed direct from the main battery cable on the back of the alternator.


The principle may transfer...?

[cinquecento]

I would check all your earth wires.. especialy the one under the drivers side of the radiator.

When mine was loose the headlights and indicators all dimmed and went back to normal in a cycle.

[Simon says]

If its any use not long after purchase my alternator started giving fluctuating readings (flickering lamps) and that was due to a failed internal voltage reg in the unit I just changed the old unit for a gen old stock Mag/Marelli from Ebay as the brushes were low too get it tested properly and don't expect to see the fluctuation with a cheap hand held analogue or digital multimeter ..... you wont

[Marty V8]

Podie said:

I had a similar issue with a Mondeo V6 a few years back, and eventually found this resolved it. It may be of use?

TSB 053/2001

[i]Summary

Should a customer express concern about flickering headlamps, wavering illumination of the instrument cluster, interior lighting and audio unit the probable cause is an extremely high resistance in the battery wiring harness from the central junction box (under the bonnet) to the B+ terminal on the alternator. To rectify the concern an additional cable should be installed.

Part number for this cable - 1133503 [/i]


Apparently the high resistance from the 7.5A fuse to the alternator multi plug causes it to "pulse" so the new loom does away with this by taking a new feed direct from the main battery cable on the back of the alternator.


The principle may transfer...?

Hi,

I thought I recognised your username but couldnt place it at first. Then I got it - Ford Forums. Ive been asking questions about Diesel Mondeos on the Ford Forums as well - just got a Mondeo ST paraffin/chip pan oil burner after my old ST24 started making very strange expensive sounds from the steering rack area.

Thanks for the reply. Something worth checking.

cheers

Marty

[Marty V8]

Thanks for all the replies chaps. Lots of food for thought.

Rob - The pulsing is at just a few cycles per second, but not much quicker.

Cinquecento - Most of the car has been strewn around the garage for best part of the year so earths are a possibility.

Simon - Sounds like the same symptoms. May I ask how much you paid for your replacement? I'd like to keep the existing one if I can but if the cost of a rectifier gets anywhere near the cost of a replacement alternator then its not worth it. The brushes on mine aren't too bad either.

Cheers

Marty

[Simon says]

About £90 as I remember that's for a Serp type (multi ribbed wide fanbelt) which tends to be the dearer unit use the numbers off the old unit A127M-100A and make sure it's the 4 lug type rather than 3 if your turns out to be faulty then this is the kiddie http://www.ebay.co.uk/itm/Brand-New-Range-Rover-Al... of course I am presuming your car is the Serpentine engined model

Edited by Simon says on Tuesday 6th September 09:34

[Marty V8]

Simon says said:

About £90 as I remember that's for a Serp type (multi ribbed wide fanbelt) which tends to be the dearer unit use the numbers off the old unit A127M-100A and make sure it's the 4 lug type rather than 3 if your turns out to be faulty then this is the kiddie http://www.ebay.co.uk/itm/Brand-New-Range-Rover-Al... of course I am presuming your car is the Serpentine engined model

Edited by Simon says on Tuesday 6th September 09:34

Simon,
Thanks for the reply.
Sods law, the serp unit would be the more expensive and yes, mines a serp motor.
Regards

Marty

[gavgavgav]

Mine did that a while ago, the dash lights 'throbbed' with the engine at idle, and as it turned out was also the cause of the idle throbbing itself. The volt gauge seemed to read normal.

I swapped the alternator with a new one and all was fixed, had smooth idle and no more throbbing. That was the solution for me.

But ....

I bought one for around £80, the new alternator let me down withing a few thousand miles, leaving me stranded at Le Mans.

I replaced that with a second and original one, which is still going strong now. The trick seems to be buying a quality one.

[Simon says]

gavgavgav said:

Mine did that a while ago, the dash lights 'throbbed' with the engine at idle, and as it turned out was also the cause of the idle throbbing itself. The volt gauge seemed to read normal.

I swapped the alternator with a new one and all was fixed, had smooth idle and no more throbbing. That was the solution for me.

But ....

I bought one for around £80, the new alternator let me down withing a few thousand miles, leaving me stranded at Le Mans.

I replaced that with a second and original one, which is still going strong now. The trick seems to be buying a quality one.

Should have made that clearer Magnetti Marelli is the OE on the Serp cars as per my link

[Marty V8]

Thanks for the info. I'm going to take it to a local auto electrician so that he can take a good look at it. Hopefully I'll have some news soon.

Cheers all.

Marty

[TimJM]

Does a Griffith have a big fuse like a Cerbera? When I had my Cerb pulsing lights in time with revs or idle was always time to change the big fuse. I had it a couple of times and both times changing the 100A fuse fixed it.

Of course if Griffs don't have a big fuse this advice is feck all use.

Tim.

[Marty V8]

TimJM said:

Does a Griffith have a big fuse like a Cerbera? When I had my Cerb pulsing lights in time with revs or idle was always time to change the big fuse. I had it a couple of times and both times changing the 100A fuse fixed it.

Of course if Griffs don't have a big fuse this advice is feck all use.

Tim.

Hi,

Yes its got one of these. Situated perfectly under one of the engine mounts...sometimes words fail me. Mine is a new 125A fuse in a new holder so I hope its not this, but worth a check all the same to see if its still all nice and tightly screwed together.

Cheers

Marty

[Marty V8]

Thread update

Got the alternator back from the auto electrician. They fitted a new bearing and new rectifier and suppressor for a total of £38.

Alternator back on car this afternoon and result - no pulsating headlights or warning lights so far.

[Simon says]

Marty V8 said:

Thread update

Got the alternator back from the auto electrician. They fitted a new bearing and new rectifier and suppressor for a total of £38.

Alternator back on car this afternoon and result - no pulsating headlights or warning lights so far.

Bargain

[pmanson]

Interesting I had a new alternator fitted in May as the old one had shorted (taking the speed with it) I've now got the same issue with the lights pulsing.

Will check the earth first but looks like it may be a similar issue.

[Marty V8]

pmanson said:

Interesting I had a new alternator fitted in May as the old one had shorted (taking the speed with it) I've now got the same issue with the lights pulsing.

Will check the earth first but looks like it may be a similar issue.

Hi,

Mine has behaved perfectly since I had it repaired - no pulsing strobe effects at all. A good auto electrician should sort this out for you for not a lot of money.

Good luck

Cheers

Marty

[pmanson]

Balls. Changed the wiper park switch yesterday to fix an unrelated issue, had the car out yesterday afternoon and when I got home switched off in the garage and battery light and heater lights stayed on.

With the keys in the ignition and foot on the brake the lights with go off (battery light stays on) so looks like the alternator is on the way out