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Alternator in lc gtr

Started by _brett1022_ , Oct 27 2019 07:52 PM

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4 replies to this topic

#1 _brett1022_

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Posted 27 October 2019 - 07:52 PM

Hi , so I've got a 55amp bosch alternator with internal regulator on my lc gtr , alternator condition unknown .I connected the brown wire which turns on the gen light and that works , and the b+ to back to the battery ,not a separate cable ,but how the factory wiring goes .Its not charging the battery , showing 12v and not rising with revs at the battery. So I tested with a multi meter from the b+ post at the alternator to earth with the battery wire disconnected from the b+ post and engine at about 900rpm and it said 18v? Does this mean the regulators cooked ? Any help please ? Thanks

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#2 limo

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Posted 28 October 2019 - 12:02 PM

I thought alternator needs a voltage load for reg to work. So with battery disconnected no back voltage. You could test there with an ammeter Is red light going off?. Does gauge show movement?

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#3 _brett1022_

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Posted 28 October 2019 - 01:10 PM

The red light comes on , then turns off when the engine starts. The amp guage has been bypassed ,the two red wires are just joined together behind it. I don't know enough about alternators to know if testing it like I did is telling me anything or not

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#4 _brett1022_

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Posted 28 October 2019 - 05:03 PM

So I disconnected the original red alternator cable and made a new one straight to the battery and it seems to be charging fine now . Something dodgy about that old cable I guess...

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#5 limo

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Posted 28 October 2019 - 05:21 PM

If red light on with ignition then off when motor running then alternator should be working. But output low as I would expect over 13 volts at battery unless the battery faulty or flat. If flat or low the voltage should rise over time. No need for high revs. You need an ammeter at the alternator to see what the output is if no dash gauge Unfortunately multi meters usually only have a 10 amp range so not high enough.