GU Battery Charging Issue

[Ben32]

Hi All,

I have a 2003 GU Turbo Diesel 3.0L. I thought i had an alternator problem so went and bought brand new Hitachi Alternator and battery still not charging. I have swapped the battery and still not charging. Battery charger is charging batteries so i know they are definitely ok. I have checked wiring and all is wired correctly, i have checked fuses and all good. Any ideas what could be causing this?? I have read a few different posts and Alternator Relays are mentioned! Where would i find this in the car?? Please help as i am keen to go for a 4wd tomo. Thanks Ben

[NissanGQ4.2]

Sorry, cant help Ben,

Just sending you a PM now

Cheers

Todd

[Yendor]

Hi Ben,

Welcome to the forum.

How do you know it's not charging?, battery light stays on in the dash? or you have measured the output at the back of the alternator and across the battery? or battery goes flat after a period of time?

There are no relays in the alternator charge circuit but a couple of other things to check are.

The small plug that connects to the alternator (with the two small wires in it) check these wires for breaks, it very common for these wires to break just near the plug. Just give a slight pull on the wire.

With the ignition on you should have 12 volts in both of these wires.

Did you reconnect the earth wire to your new alternator?

[Ben32]

Hi Yendor, Thanks so much for your reply. I know its not charging as i have used a multimeter and checked the output at the back of the alternator and at the battery. I also have a dual battery system with a battery metre inside the cab which is showing me the same result. I was alterted to the problem when out 4wdriving last weekend as the battery metre inside the car sounded an alarm telling me low power. I am not sure if it could be related but this occured after having to drive through a bit of water on the beach. Not a massive amount of water but i am thinking it may be possible water has got into something. I have reconnected the earth wire. This is really frying my head as i cannot figure out and i think i am now too far involved with it so others opinions would be great. Thanks so much Ben

[Ben32]

Hi Yendor also just a thought the battery light on the dash is not coming on with this issue so could it have anything to do with this?? Does that make part of the circuit?? I have just tested the earth from battery and it is fine. AHHHH this is really annoying lol

[Yendor]

Does the battery/alternator warning light in the dash come on when the ignition is turned on? does it then go out when the engine is started?

At a fast idle (just use the idle up switch on the RHS of the dash) what is the voltage reading across the alternator (neg lead of voltmeter on the alternator case and pos lead on the large wire? what is the reading across the battery?.

Have you checked the two wire connector at the alternator as per my previous post.?

Was the replace alternator brand new or a reconditioned one or one from a wrecker?

[Ben32]

Hi Yendor, The light does not come on the dash with ignition on or started.

The voltage reading across the alternator is 11.4 with idle up and 11.6 at battery.

Checked the 2 wire connection and it is fine.

It is a brand new Hitachi alternator.

[Yendor]

Hi Yendor, The light does not come on the dash with ignition on or started.

The voltage reading across the alternator is 11.4 with idle up and 11.6 at battery.

Checked the 2 wire connection and it is fine.

It is a brand new Hitachi alternator.

So you have power in both wires with the ignition on?

Do your other warning lights in the dash work when the ignition is turned on? such as sub tank warning light?

Check all the fuses in the fusebox inside the vehicle, especially fuse number 26

[Ben32]

Hi Yendor, All my dash lights work expect the sub tank light stopped working just before i had this problem with the charging.

All fuses are fine i have tested them. 26 is fine.

thanks Ben

[Ben32]

Just testing my batteries and i have eliminated one from the circuit and the power output has dropped to 7. i am now charging the other battery and trying that one just to make sure it isnt a battery issue. If anyone has any other ideas please help.

[Yendor]

Ok, we are back to the connector at the alternator. I know why you don't want to do this because it is a real PITA to get at with the second battery fitted.

You need to make sure the plug is fitted all the way into the alternator, they are very tight. If this is ok, you need to disconnect the plug and check for power with a voltmeter in both wires with the ignition on.

Don't reconnect the plug just yet, let us know what the results are first.

At the moment your alternator is not charging, this could be due to a faulty alternator or a problem with the wiring.

[Ben32]

Ok, I have unplugged and tested with ignition on and nothing. I am getting nothing at all. What does this mean?? Thanks Ben

[Yendor]

There is a fuse in the fusebox under the bonnet fuse 47, make sure this is not blown.

You need to remove some of the tape and insulation from the wires near the connector and make sure the wires are not broken.

[Ben32]

Thanks, a little help with fuse 47. My fuses arent numbered. What is this fuse for?? Trying to find it but having trouble. Thanks

[Yendor]

On the plastic fuse panel cover it is labeled as " ALT S " and is a 7.5amp fuse, it's the next one up from the hazard light fuse.

[Yendor]

It is the alternator sense circuit fuse, this is how the alternator knows what charge the main battery is getting.

If this fuse is blown if will only account for why one of the wires doesn't have power in it.

[Ben32]

Fuse is fine. Just replaced it and tested from plug of alternator with ignition on and still nothing. I have pulled the tape off the plug and wires are all intact. Any other ideas. ???

[Yendor]

You are checking vehicle side of the connector?

There is no common connector that both these wires run through. So you will need to follow the wire harness back from the alternator looking for any signs of damage.

I have attached the wiring diagram hopefully this helps.

[Ben32]

Hi Do you have a diagram legend so i can find the fuses ect on the vehicle. I am just going back through everything. I am trying to find the M143 just to eliminate the issue with this one. (If this all fails i am going to grab 2 new batteries and try them).

Thanks Ben

[Yendor]

M143 is the connector at the back of the instrument cluster.

I think you might need to take the vehicle to an auto electrician.

[Ben32]

Thanks for all your help. I am now going to have to get an auto sparky, this is now way over my head and i cant find the path of the wiring. Guess no 4wdriving this weekend :( I will let you know what the result is so you can have it for future knowledge incase it happens to someone else lol

[Yendor]

Yes, let us know how you get on. Hopefully they can sort it out for you quick smart.

Cheers Rodney

[Ben32]

Hey Rodney i am still playing with it and have discovered a red wire that comes off the battery that goes to a fuse, then this connects to a black box that is earthed to the side of the inside of the engine bay. This black box has BOSCH on it. I dont know what this is for. Do you have any idea. The fuse in this red wire looks a little melted so could this cause the problem. Another person has had a look and said it has nothing to do with it. I have put 2 new batteries in just incase it was one of those that was causing issues. Thanks Ben

[Yendor]

Possibly a relay for something like spotlights, are you able to post a picture?

[NissanGQ4.2]

Good 2 see someone not giving up.

Did you get the PDF file 2 work???

[Ben32]

I tried to post pics but it wouldnt work. I have discovered the red cable and black box are the wiring for the battery display inside the car. I have replaced the fuse with another and played around a bit more and tested and still nothing. So i am now giving up and i will have to call auto electrician lol at least i have eliminated a heap of possible things so it will make it easier for the lecky. Thanks so much for your help

[NissanGQ4.2]

What file size are the pics, anything over 1.9MB will not upload 2 the forum, most Digital camera's u will find the file size is over the 1.9MB

You may need 2 reduce the photo's before uploading them.

Cheers

Todd

[Lieney]

I haven't got a Nissan Patrol wiring diagram but I would love to get my hands on one. I'll give you what I can think of.
In some electrical charging circuits, the alternator light is connected to the exciter circuit of the alternator (turns it on) so if the globe fails, the circuit cannot excite / turn the alternator on and thus it will not produce current for charging.
When the ignition key is turned, current flows from the battery, throught the ignition switch (dash etc) via the warning light (or the reverse) and earths out through the alternator internally.
As I said, not sure if the Patrol has the same as circuits that I have played with over the past years, but I woul be checking the globe in the dash.
The alternator requires current flow to produce a magnetic field and create energy.
Are you certain the new alternator works correctly?
Ensure the surfaces where it mounts to the engine etc are clean and that a good earth is present.
There are more checks I can think of but it's hard to type it in.
Does the alt get ignition power?
Does the alt get B+ power from battery?
What is the resistance from battery - post to alternator body?

Let us know what it is?

[NissanGQ4.2]

I haven't got a Nissan Patrol wiring diagram but I would love to get my hands on one.

You do know you can download it from the manual section of the forum

[Ben32]

Hi Lieney, Here is where i have got to. I am getting some charge from alternator but not enough i am only getting 11.8 from alternator on high idle. I have checked every fuse and the way my car has been wired there is ALOT of fuses lol. I have changed them all and no change. I have checked all wiring i can see, i have pulled the dash out and checked all wiring. I have replaced alternator and getting exact same reading as previous alternator. I have also replaced batteries with 2 brand new batteries just in case. I have checked all earths pulled them off cleaned them. Now with all my mucking around my dual battery control unit inside the car has decided to stop working. I can hear it click on with ignition but the display is not working. This item is wired to a relay then to the battery and earth. I dont know if this is at all relevant that it has decided to not work. I have had a few mates one who is an electrician have a look and he cant come up with any solution. I know it is going to be something completely stupid but nothing is standing out. I have checked resistance from every angle possible lol i have the dash out so i will check the globe in the morning. Its basically the last thing.

[Yendor]

When you were checking for12 volts at the alternator plug did you have the instrument cluster plugged in?

[whits86]

Main or aux battery? Not an isolator?

[DAV30]

have you fixed this issue yet if so how my 01 gu has the exact problem

[garryboy]

Just testing my batteries and i have eliminated one from the circuit and the power output has dropped to 7. i am now charging the other battery and trying that one just to make sure it isnt a battery issue. If anyone has any other ideas please help.

I might be a stupid question, is your battery AGM or Normal battery. AGM batteries cannot be charged with conventional alternators if below capacity. It happens on 2003 Landcruiser. It might help ..

[OuchOne]

Why do people not come back and actually tell others how they resolved their issue? Oh I fixed it, don't need the forums help anymore.
:1087:

[Ecronic]

Hi all, I'm facing same issue. I know this is an old thread and hoping I can resolve it.

6months back my alternator failed and stopped charging my battery. I thought it was old battery so replaced with a brand new one and it got drained. I sent the car to a garage and they replaced the alternator with a used part from the wreckers. So far it worked properly until a week ago I noticed that the voltages were dropping as below:

1. Ignition switch "On Position" - voltage read 11.8-11.9v
2. On start/ crank - voltage reading drops to 7.8-9v
Car starts almost immediately without any issues(long cranking starts etc).

Note: these voltage readings are taken from my aftermarket android stereo.

I am yet to test the battery with a multimeter(will be done on Saturday only). Besides testing the battery, is there anything else I should be testing or inspecting related to this issue?

[mihit]

Hi all, I'm facing same issue. I know this is an old thread and hoping I can resolve it.

6months back my alternator failed and stopped charging my battery. I thought it was old battery so replaced with a brand new one and it got drained. I sent the car to a garage and they replaced the alternator with a used part from the wreckers. So far it worked properly until a week ago I noticed that the voltages were dropping as below:

1. Ignition switch "On Position" - voltage read 11.8-11.9v
2. On start/ crank - voltage reading drops to 7.8-9v
Car starts almost immediately without any issues(long cranking starts etc).

Note: these voltage readings are taken from my aftermarket android stereo.

I am yet to test the battery with a multimeter(will be done on Saturday only). Besides testing the battery, is there anything else I should be testing or inspecting related to this issue?

HOW did the alternator fail? (rectifier, bearings, windings?) Might give some clue.

Those voltages seem incredibly low and to me suggest an undersize battery or one with low internal resistance. Resting voltage should be 12.2-12.8. This may drop significantly on cranking but I wouldn't expect below 10. Glow plugs will soak up certain current but not enough to cause that kind of voltage drop.
Charging (engine running, alt working) voltage should be 13.2-14.4 depending on batteries current charge state.

I wouldn't trust a -stereo- (??) unless it's wired directly to the battery with wire sized apropriately for the current and cable length (10A minimum)

Testing for parasitic drain is done with a clamp or ammeter in between the main hot wire and battery terminal. There will be certain "standby" current for computers, clocks, etc. if there's anything over 1A that would be cause for concern (to my mind, new cars will have more electrickery) - with the ammeter still in circuit, pull house fuses one by one until the current goes low, then you've identified the circuit drawing power.

It seems maybe this is a common fault? And no-one's worked it out?

Alternators require a "field" or "sense" wire and this may be undersized, worn, shorting, etc. I would run a new wire direct from positive battery terminal to this "field" pin/pole/terminal, 5A wire should do as it's only measuring voltage (batteries' current charge state) and providing the excitation for the field. But bigger wire never hurts and 10A is cheap enough.
Try and find a wiring diagram for the alternator but I think the field pin is normally marked "B"

If it's all going through some f*cking computer...then it's probably the f*cking computer.

Alternators are simple devices, and the three things at the top are about all that can go wrong. Re-wiring a rectifier bridge isn't hard and costs <10$ in diodes. Bearings are same as any other bearing job. Windings, unless you're in BF-nowhere, would be throwaway/replace, but it would be good to know WHY they failed.

[Ecronic]

HOW did the alternator fail? (rectifier, bearings, windings?) Might give some clue.

Those voltages seem incredibly low and to me suggest an undersize battery or one with low internal resistance. Resting voltage should be 12.2-12.8. This may drop significantly on cranking but I wouldn't expect below 10. Glow plugs will soak up certain current but not enough to cause that kind of voltage drop.
Charging (engine running, alt working) voltage should be 13.2-14.4 depending on batteries current charge state.

I wouldn't trust a -stereo- (??) unless it's wired directly to the battery with wire sized apropriately for the current and cable length (10A minimum)

Testing for parasitic drain is done with a clamp or ammeter in between the main hot wire and battery terminal. There will be certain "standby" current for computers, clocks, etc. if there's anything over 1A that would be cause for concern (to my mind, new cars will have more electrickery) - with the ammeter still in circuit, pull house fuses one by one until the current goes low, then you've identified the circuit drawing power.

It seems maybe this is a common fault? And no-one's worked it out?

Alternators require a "field" or "sense" wire and this may be undersized, worn, shorting, etc. I would run a new wire direct from positive battery terminal to this "field" pin/pole/terminal, 5A wire should do as it's only measuring voltage (batteries' current charge state) and providing the excitation for the field. But bigger wire never hurts and 10A is cheap enough.
Try and find a wiring diagram for the alternator but I think the field pin is normally marked "B"

If it's all going through some f*cking computer...then it's probably the f*cking computer.

Alternators are simple devices, and the three things at the top are about all that can go wrong. Re-wiring a rectifier bridge isn't hard and costs <10$ in diodes. Bearings are same as any other bearing job. Windings, unless you're in BF-nowhere, would be throwaway/replace, but it would be good to know WHY they failed.

Thanks for your reply mihit.

The issue is sorted. Actually there was no issue to begin with as the reading from the stereo was quite off. The steady idle voltage the stereo displayed was 13.2-13.6v but just the on position and crank voltage was completely off. So, to test correct values I did the following:
1. Connected a DMM to the battery - reading was 12.8v
2. Turn the key to on position - reading was 11.6v
3. Cranked - reading was just below 11v

I also kept the DMM connected and did a high idle test to 2000rpms and the voltage started increasing so I'm sure now the alternator is charging the battery as well. Not going to rely on the stereo voltage display.

The alternator failure cause wasn't anything electrical. It was just life failure. It was never changed since I bought the car so basically it failed after literally 14years. To be honest though couple of times I have stretched the use of a dying battery a couple of times previously, the start was long, service advisors asked to change the battery but delayed until car was completely dead at times and also due to this, my starter has also given up. Lesson learnt though, no more stressing other parts due to weak battery. Just change it in time.

I do have quick query though, I'm planning of using a very simple system to monitor the voltage when the car is running. I just can't decide what would be the correct way of having the voltage display. Could you guide me if any of these are the correct and of course a safe way.

1. 12v LCD voltage display with inline fuse of 10A connected to the internal fuse box to a switched power source.
2. 12v LCD voltage display on a USB charger connected to the lighter(not sure about the fuse in it but if I'm not mistaken most of them come with 1.2-2.5A)

thanks

[mihit]

everyone loves a happey ending :)

Well... since all my alternators have been going for ~30 years... it does strike me as odd that after "only" 14... one should fail ;)

I would find a "hot-when-on" wire (on the gq this is second relay from firewall beside RH battery) and splice into that to trigger a relay.
Relay obviously to run power to the voltmeter. (I assume GU no longer have voltmeter on dash??)

[BrazilianY60]

GU dash does not have the four lateral gauges as the GQ does. Only fuel and water temp, which is a shame and also make the dash look full of nothing.