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1998 RR P38 4.6 HSE LHD German spec, now on sequential LPG
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55 Posts
Discussion Starter · #1 ·
Hi,
I have noticed that all internal lights and displays and also the headlights flicker. Roughly about 5 times a second, but the same in idle as when driving.
Ground cables are clean and OK.
Guess it could be the alternator but it is only a good year old (Denso 120A from island4x4)...
Is there a way to check that ? Would like to know for sure before I order another one all the way from UK...
I also have a Oszilloscope at home but would have to find out how to use it ...would that help ?
Thanks,
Max.
 

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1995-2002 Range Rover P38A
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563 Posts
Are the headlights flickering too. When I noticed flickering I kept driving and then started getting alt fault on the screen. Then I carried my ohmeter and when the fault happened I tested the battery and it was 11.5. I would get a new alternator from a reputable brand. I put a new alternator off ebay and it works great again.
 

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1995-2002 Range Rover P38A
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602 Posts
use the electrical sticky at the top of the page.https://www.rangerovers.net/threads/info-electrical-troubleshooting.28663/unread
 

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1995-2002 Range Rover P38A
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665 Posts
I doubt it is the alternator. Measure your voltage at the battery while engine is running. See if it is steady and somewhere around 13.8. More likely a loose connection or fuse box.
 

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If the regulator in the alternator starts to fail the lights would normally pulse but at a fat lower rate than 5 times a second, nearer a couple of times a second. Multimeter won't react fast enough to show you the problem but a scope will.
 

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You can always disconnect the alternator (tape up the lose wire!) to check if the problem remains or not.
 

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You can but you need to disconnect both wires so the alternator isn't trying to do anything.
 

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Are the headlights flickering too. When I noticed flickering I kept driving and then started getting alt fault on the screen. Then I carried my ohmeter and when the fault happened I tested the battery and it was 11.5. I would get a new alternator from a reputable brand. I put a new alternator off ebay and it works great again.
I had the same issue of all lights flickering including headlights and dashboard lights. Then suddenly when I parked the vehicle and turned it off the truck went completely dead. Found out it was a loose battery cable connection at the battery.
 

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1998 RR P38 4.6 HSE LHD German spec, now on sequential LPG
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55 Posts
Discussion Starter · #11 ·
OK, my fault....!

Some time back I had installed a second thick cable from the alternator positive to the battery positive to overcome bad connections and the cable was not perfectly flat on the terminal. Once I disconnected that the voltage was staedy and the flickering stopped. Installed the cable better and now everything is steady.

It´s not like the P38 didn´t have enough tricks on it´s own to keep me busy, no, I had to throw in a couple of mistakes too just to make it more challenging...^^ !!

But thanks for all the input, it helped me find the mistake.
 

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It is my understanding it is not a good idea to run an alternator with its output disconnected.
True, I should have been clearer that both the thick wire and thin wire need to be disconnected for the test, and taped up to avoid shorts.

Good to hear the problem is solved!
 
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