Total electrical failure

[Paul64]

Hi Paul,

I'd stick the new one on and get the other(s) checked out , before you do a quick test is to disconnect the main charge wire - thick brown one- with ign off everything switched off but vehicle battery connected , set your test meter to amps hold the red probe on the brown wire and the black one on the stud the wire was connected to . Any reading at all would indicate a faulty diode pack , which is also suggested from your results on the move ie lower volts at revs than at tickover.

Note that the heavy brown wire will be live so don't earth it

hth

Steveb

Thanks Steve

[jacks906]

without sounding rude as i'm not sure best way to word it all but,

i dont see how a faulty alternator problem can cause now dash lights/no starting/no power, yet it has been said there is power when the truck is turned off but not when it comes to restart it. granted there is a problem there with the alternator charging but i dont see how this can be the starting problem

[steve b]

..Seems to me that there are 2 problems alt, and intermittent complete loss of power, on the 2nd one I think I,d start with a complete new set of earth and starter/main supply leads to eliminate a hidden cracked conductor. Do you have the main vehicle fuses beside the heater box mounted on the bulkhead?

...I might have to re-read this from the start to refresh t'grey matter

[Paul64]

without sounding rude as i'm not sure best way to word it all but,

i dont see how a faulty alternator problem can cause now dash lights/no starting/no power, yet it has been said there is power when the truck is turned off but not when it comes to restart it. granted there is a problem there with the alternator charging but i dont see how this can be the starting problem

I thought that too Dave, as the two batts are at over 12V when I loose all power. So there is charge getting to the batteries even if it is weak, but certainly enough to start the engine, so why the temporary and complete loss of power after the engine is turned off?. I should have also said that the 2nd battery is the one with the braided earth.

Cheers, Paul

[David Sparkes]

Can you recommend a way of fitting the probe to alternator output or casing whilst driving?

Given the history, I would look to make a 'good' (semi-permanent) job of installing a pair of test wires to the alternator, and feed these into the cabin where your meter is. In the cabin I would terminate these wires in a 'chocolate block' screw terminal strip. To give me a bit of a safety margin I'd use a strip of about 4 connectors, leaving the middle two unconnected, with the alternator output and alternator casing leads terminated in the outer connections. I'm hoping your meter leads have 'rod' probe ends as an alternative to spring clips. Choose your connection strip large enough to be able to push the probes in and have the screws clamp the probes.

At the alternator I'm guessing that the alternator output connector is a stud, but it could be a large 15Amp male Lucar. To protect the test lead I'd prepare an inline fuse holder with the appropriate terminal, as the output terminal has full battery current behind it. If the test lead hits Earth it will melt, and molten metal makes your flesh sizzle. Make the connections as good as you can, even down to smearing the ends of the 5 or 10 amp fuse with Petroleum Jelly (Vaseline). Because I can, I solder connections rather than crimp them.

To connect to the casing, solder a ring terminal on the end of your test lead and fasten under one of the alternator mounting bolts. Make sure that one side of the ring terminal is touching the casing directly, not just a washer that then connects to the casing.

As I've indicated by the fuse size, the wires don't need to be thick, but choose wires large enough to be mechanically robust.

Solid Brown and solid Black (with no tracers) are the correct colours for these wires, but it depends what is available. If you do use odd colours, wrap BOTH ends of each wire in Black tape for the casing connection, and Red tape for the Output connection.

Bind the wires as a pair because it makes for a neater and safer installation.

Length of wire is not signigicant, as they aren't carrying much current.

Apart from the fuse ensure there are no joins in the wires. Iffy test equipment gets very irritating.

As a point of interest I did buy a new alternator last month as a back up. Do you think it is better to stick with the testing or just swap over to the new alternator?

I still have no clear idea why the whole system is dying, then repairing itself.

We are chasing the alternator at the moment because it appears to be throwing a consistent fault we can check on.

Having come so far, I'd rather finish the alternator testing, even if it does mean you have to change it.

Testing it to the end also means (IF it proves faulty) you can be certain that when you hand it in for overhaul, or a new regulator or diode pack, you know why you are asking for specific work to be done. You can even be specific as to what you found wrong if you hand it in for testing by a specialist.

Even if you fit a new alternator, I'd still expect you to test it and 'know' it's working OK, rather than leave it in a 'wait and see' mode.

I'd also expect you to test the installation again when you reconnect the second battery.

Cheers.

[David Sparkes]

Jacks906 and Steveb,

Not rude at all, I agree entirely, there appear to be two problems, and I don't have a clear idea about the total power failure and self repair. I can guess, but that doesn't get it repaired.

I'm taking the view that it's better to chase the simpler fault and get rid of it, then concentrate on what's left.

I'm not blind to the possibility of stumbling across the cause of the power cut while working to fix the first fault, but I'm not banking on that happening.

Given the history of the vehicle I'm not willing to suggest wholesale spending of time and money on a 'change this, change that' basis.

The 'cracked connector' at the fuse box is a good suggestion. It was the principle I had in mind when I asked Paul to give a good tug at the earth cables connected to the gearbox.

If Paul gets bored or irritated with the slow progress of the long distance faulting then he can do the 'throw money' option, that's his decision, but I would like to know why I'm asking him to spend money.

Cheers

[Paul64]

Wow David thanks for all that, but it is getting a bit complicated for my mechanically untrained mind My cousin David will vouch for my complete inability for most things mechanical! I don't have a solder gun or any asbestos gloves I have a REME electrician friend coming over sometime so I may ask him if he has any test equipment in his army workshop. That way I could fit my new alternator whilst the old one is being tested? I don't want to put a damper on all your good work, but at the same time I don't want you thinking that I am in anyway competent with electrics

Cheers, Paul

[David Sparkes]

Paul, I have had in mind your lack of experience in matters electrical, which is why my responses have tended to go into the fine detail. I didn't want to 'assume you understood'.

You have successfully done the basic voltage tests, so if you want to take a short cut then fit the new alternator and repeat the tests.

Cheers.

[Paul64]

Thanks David, but after that said I still cannot understand how a battery charged at over 12V can lead to a temporary but yet complete loss of electrics for the whole vehicle.

Cheers, Paul

[Paul64]

..Seems to me that there are 2 problems alt, and intermittent complete loss of power, on the 2nd one I think I,d start with a complete new set of earth and starter/main supply leads to eliminate a hidden cracked conductor. Do you have the main vehicle fuses beside the heater box mounted on the bulkhead?

...I might have to re-read this from the start to refresh t'grey matter

Sorry, I missed this one Steve. The fusebox is just in front of the gear stick. Can sets of leads be bought, or is it better to buy cable lengths and make them up yourself? Any recommendations where to buy that does mail order?

Cheers, Paul

[steve b]

I make my own with fully soldered ends, but OE will be available thru main stealers and probably thru the likes of Bearmach . Welding earth lead 35mm2 at least works well .

The 2 fuses I'm talking about are in the engine bay and iirc are 70a each and are first in line from battery to the rest of the vehicle , supply is from starter terminal...have you checked this is tight?

cheers

Steveb

[Paul64]

I make my own with fully soldered ends, but OE will be available thru main stealers and probably thru the likes of Bearmach . Welding earth lead 35mm2 at least works well .

The 2 fuses I'm talking about are in the engine bay and iirc are 70a each and are first in line from battery to the rest of the vehicle , supply is from starter terminal...have you checked this is tight?

Thanks Steve, I have not seen any fuses in the engine bay and I haven't checked any connectors at the starter. Are you saying that I should check the main feed connector to the starter motor?

Cheers, Paul

[TD5 power]

hi

Have you tried connecting a jump lead between the alternator casing and the main battery negative terminal, this would eliminate any earthing issues.

I have a theory that the main earth lead is failing internally, as it heats up during driving the resistance increases limiting current flow giving the impression the alternator isn't working correctly. When the truck is warm the connection inside the lead is broken meaning no current can flow and therefore no lights etc however as it cools down the connection is remade and the problem appears to fix itself.

hope this makes sense

matt

[jacks906]

hi

Have you tried connecting a jump lead between the alternator casing and the main battery negative terminal, this would eliminate any earthing issues.

I have a theory that the main earth lead is failing internally, as it heats up during driving the resistance increases limiting current flow giving the impression the alternator isn't working correctly. When the truck is warm the connection inside the lead is broken meaning no current can flow and therefore no lights etc however as it cools down the connection is remade and the problem appears to fix itself.

hope this makes sense

matt

thinking back now paul

when i was over there and we went big mama's (very nice indeed and the food was nice too ) we came back to the truck and it wouldn't start did this to start it when you went to borrow a battery was this the same or another reason?

dave

[steve b]

If the main vehicle live terminal at the starter is loose or has a dodgy connection you would get all these symptoms i think..

Steveb

[Paul64]

thinking back now paul

when i was over there and we went big mama's (very nice indeed and the food was nice too ) we came back to the truck and it wouldn't start did this to start it when you went to borrow a battery was this the same or another reason?

dave

That was different Dave as the engine was turning but really slowly. You connected both batts and she started. With this problem, there is total loss of power - everything.

By the way I went back to Big Mama's in January and had one of their big mama cheeseburger specials. No wonder our guts grew so big!

Have you tried connecting a jump lead between the alternator casing and the main battery negative terminal, this would eliminate any earthing issues.

I have a theory that the main earth lead is failing internally, as it heats up during driving the resistance increases limiting current flow giving the impression the alternator isn't working correctly. When the truck is warm the connection inside the lead is broken meaning no current can flow and therefore no lights etc however as it cools down the connection is remade and the problem appears to fix itself.

Thanks Matt, but thus far this problem has only occurred when driving through rain? It has been dry this afternoon and didn't do it once?

Cheers, Paul

[Paul64]

If the main vehicle live terminal at the starter is loose or has a dodgy connection you would get all these symptoms i think..

Steveb

Thanks Steve! What do you think Dave as the feed connector did fall off twice whilst you were over. I can't remember whether you changed it or nipped it up the last time it happened?

Still not sure how that would lead to temporary total loss of power though? And does water reach right up there when driving through rain?

Cheers, Paul

[Paul64]

Been outside for another fiddle. The rain is a red herring as the power went off again today and it is dry and windy.

Something interesting did come out of the afternoon though. I had a look at the main feed to the starter motor as suggested by Steve. I could only see the wire disappearing below the turbo manifold and to the starter, but I could just reach the connector with two fingers. I gave it a bit of a wiggle and pushed it in place as much as I could. Although it didn't feel loose when I turned the engine I noted the idle voltage crept up to 13.67 which is half a volt higher than yesterday. also did the same run as yesterday to compare readings. The reading did dip slightly but not as much as yesterday and hovered around 13.43V throughout the run.

Cheers, Paul

[Paul64]

Some good news to report, no more total electrical failures for 3 days now:) A nice REME mechanic parked my Land Rover in the biggest garage I have seen in my life. It was a bit of a squeeze but we parked it in between two tanks! Anyway, he did several tests and said the diode pack was not working properly on the alternator so changed it with the new one I bought. Instantly the V reading just up to 14V:)

He then did a series of tests including the earths. He said both batt neg earths were ok but there was some resistance between the gearbox and the chassis, so he fitted an earth cable between the two. My other electrical gremlin with wiper activating when using lights has now also gone:) Looks like a good result but as always time will tell.

Thanks for everyone's help and a very big thank you to the British Army!

[ARMYBOB]

we aim to please, and you are welcome!

as Paul has said, the alternator is working but not quite as well as i would have liked, the new one threw the voltage straight up so confirming the old one as not dead but dieing.

checked for neg earth between engine and chassis with varying resistances, nothing high but i would expect nothing so made another earth cable out of some heavy duty stuff i have and the resistance was gone.

until it happens again(if) we cant confirm if the problem is solved or not.

as for Tanks, i told paul i work on tanks day in day out, nothing i touch on a day to day basis is worth less than 3 million pounds and i just crack on without hesitation, its second nature

however working on a friends old land rover reduces me to a nervous wreck, why? i guess the implications of screwing it up are more severe.

anyway, not to correct Paul too much i am an electronics technician, i do electrics at every level, but i also fix:LASERS, servos generators hydraulics optics thermal imaging systems guided weapons etc etc.

but i loves my landy's

[David Sparkes]

....

checked for neg earth between engine and chassis with varying resistances, nothing high but i would expect nothing so made another earth cable out of some heavy duty stuff i have and the resistance was gone.

Interesting to see a possible parallel with what I've been told about the 4.6 V8, and put in post #15

"However ....

I am reminded of the repeated cases of the engine earth strap on the petrol V8 engine in the 38A.

This is a standard cable, with lugs crimped on both ends. Bolted low down on the engine it gets covered in any oil leaking from the rocker covers, together with dirt and water from road spray. Add in the vibration from the engine, together with the heat cycling from the engine warming and cooling, and the relatively stiff cable strands start to work loose inside the crimp, allowing corrosion to take place."

Regards,

[ARMYBOB]

i didnt know where the original earth, and couldnt find it

to be a honest a friend had suggested a similar problem with his series.

easy to just make another

[Paul64]

It's happened again, but this time worse than before. I was filling up at the garage and couldn't start the Defender up again. As before total electrical power failure, no lights on the dash, nothing. Tried to get my arm down to the starter motor and burnt my arm on the manifold which wasn't too clever. Fuses are all good and full power in both batteries. Strange thing is if I leave the ignition on occasionally the ignition lights glow on then fade again to nothing. When the lights glow on I can get the starter to click but nothing more, when the lights fade the starter is completely dead. Some German guys helped me out by pushing and jump starting the engine which got me home.

The only thing that is different compared to last time is a big earthing strap was connected by a mate from the gearbox to the chassis and a new alternator has been installed. Any ideas?

Cheers, Paul

[jbs]

Just out of curiosity is the ignition switch on it's way out? the reason I ask this is because I've problems in the past where I've lost all power driving down the road-slowly thank goodness! and I've lost all power to the 90 I was driving it turned out to be in my case a very tired ignition switch and replacing it has as far as I know cured it

HTH

John

[Paul64]

Just out of curiosity is the ignition switch on it's way out? the reason I ask this is because I've problems in the past where I've lost all power driving down the road-slowly thank goodness! and I've lost all power to the 90 I was driving it turned out to be in my case a very tired ignition switch and replacing it has as far as I know cured it

HTH

John

My cousin mentioned that possibility a while back, but I can't see how that would effect all electrics including the alarm system? I find it strange how the power slowly seeps back after instantly loosing it. Now two hours later the ignition lights have come back on but there does not seem to be enough power to turn the starter properly. I made a short video.