L322 4.4 V8 high voltage boiling battery 17v+

Hi, i have this Exact problem on my 2007 L322, 12.8V with engine off, 15V at idle, and 18V going down the road which shuts all the systems down.
I've changed the alenator 2 times now and it still does the exact same thing.

tomcat59alan said:

There's more American volts to our British volts, I'm not into electrickery but I would hazard a guess at the voltage regulator.​

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is the voltage regulator internal on the alternators?

Dean07L322 said:

is the voltage regulator internal on the alternators?

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It is on mine but it's a P38 , hopefully someone with experience will answer.Welcome to the mad house.

does anyone have a diagram of the wires going into the alternator and which pins the wires go too? the plug disintegrated when it came off, and im not sure my mechanic put them back correctly.

tomcat59alan said:

It is on mine but it's a P38 , hopefully someone with experience will answer.Welcome to the mad house.

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Thanks, lol

Dean07L322 said:

does anyone have a diagram of the wires going into the alternator and which pins the wires go too? the plug disintegrated when it came off, and im not sure my mechanic put them back correctly.

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Which could possibly account for your problem.

Check earths too. Maybe an extra one to engine?

Dean07L322 said:

I've changed the alenator 2 times now and it still does the exact same thing.

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Have you replaced the battery?
It could be the battery is going open circuit, allowing the voltage to climb excessively.