Alternator Fun!

Discuss (and cuss) the Nissan LD-series OHC Six diesel engine, popularly available in the US in 1981-83 Datsun/Nissan Maxima Sedans & Wagons.

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Major Eyeswater
Posts: 9
Joined: 10 years ago
Location: Southampton, Hampshire

Alternator Fun!

#1

Post by Major Eyeswater »

Hope some bright spark here can help.
My LD28 is fitted in to a LR Defender after much delays I have finally got it back on the road.

Well all was fine till the battery went flat this weekend prompting me to look at the alternator battery etc, so here is the short version of my work this morning and questions that puzzle me, based on that it all worked fine before the engine in out earlier this year.

1, Battery is good and only a few weeks old so no problems there.
2. Volts at battery and back of alternator only reach 12.38V
3. The plug for the alternator has historically been cut at point of implanting the the engine, there are 2 thick brown cables that are and have always been connected to the back of the alternator
4. there is a smaller cable with a spade connector which has been connected to one of (and here might be the answer) but I'm not sure which one of the 2 spade connectors available where the plug would have connected.
5. When this wire is connected in either position nothing changes to the charging.
6. I have read a fair amount on line that suggested that i also need an exciter cable running direct from one of these connectors to the battery, so I have tried that in both positions, firstly in the lower connector where nothing happened then in the top one where the alternator became difficult to turn squealing the belt and creating magnetism on the front of the crank voltage across battery went up to 12.6V still not any where near the 13-14V I'm expecting.

So am I barking up the wrong tree with the exciter cable?
anything else I should check?


I have a cold, it is raining and I have given up for the day. I have added a picture of the Alt and the connection plug.

Please help if you can.

Rob
Image
LD28 in a 1990 Land Rover 90
alramone
Posts: 16
Joined: 10 years ago

#2

Post by alramone »

i'm pretty sure one of the spade terminals is for the ignition light, and the other one should be conected to the battery positive, to sence battery voltage and tell the alternator how much to charge.
i'll have a look on mine tomorrow and see how mines conected.
i've got a ld28 in a rrc. and i'm in hampshire too :wink:
Major Eyeswater
Posts: 9
Joined: 10 years ago
Location: Southampton, Hampshire

#3

Post by Major Eyeswater »

Cheers Bud,

lot of head scratching and I know it should be simples!
LD28 in a 1990 Land Rover 90
alramone
Posts: 16
Joined: 10 years ago

#4

Post by alramone »

looked on both of my LD engines and they have different shaped plugs.

it may be the same as nissan 200sx alternator. i'll have a looksee
alramone
Posts: 16
Joined: 10 years ago

#5

Post by alramone »

found this pic of a 200sx alternator. it's upside down as it's on the other side of the engine, but you can see the thicker wire is the one that goes to the battery so the smaller one is for ignition light.
so i'd put my money on saying the upper conector on your alternator goes to the battery and the lower one goes to ignition light
Image
Major Eyeswater
Posts: 9
Joined: 10 years ago
Location: Southampton, Hampshire

#6

Post by Major Eyeswater »

Cheers Bud!

I'll be having another play this weekend
LD28 in a 1990 Land Rover 90
alramone
Posts: 16
Joined: 10 years ago

#7

Post by alramone »

had another look at my alternator last night. i do have the same one as yours and mine wasn't wired up correct either :lol: whoever put it together didn't connect up the exciter wire. (they also only had one main feed coming off of the alternator. i fixed that too)
i tested the battery voltage with engine not running. around 12.5 volts.
tested voltage with engine running and exciter not conected. 15.3 volts !
tested voltage with engine running and exciter conected to battery. 14.3 volts. sorted.

so lower of the spade terminals is for ignition light.
upper spade terminal is the exciter and should be conected to the battery.
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