Gearbox fault and electrical issues, P38A Diesel.

Afternoon all,
My wife's P38 Diesel has thrown up a gearbox fault and I'm looking for any advice having searched the forums.
It happened when she was stationary in traffic in neutral, she moved the selector to drive and it gave gearbox fault on the dash. It also said Fuse 6 fail, Fuse 7 fail, Fuse 17 fail.
The gearbox went into safe mode/limp home mode and will not change from what I am presuming to be 3rd.
When she got home I checked the fuses and 6, 7 and 17 were all fine.
As well as the gearbox fault and fuse failure being displayed on the dash the hevac unit is no longer working and is off completely, the air suspension height indication light has now gone very dim although the suspension is working, the gear selection indicator light by the selector itself is very dim.
I have done some electrical checks and have found the following;
Battery test with engine not running after 30 seconds of load with headlights/mainbeam on and radio (as hevac not working I have not been able to use the demisters) - 12.52v,
Charge circuit at battery with no load and at 2k rpm - 13.62v,
Charge circuit at battery with load at 2k rpm - 13.36v,
Alternator direct at idle - 13.98v,
Negative cable loss check under load - 0.27v,
Positive cable loss check under load - 0.19v,
Voltage drop between negative terminal at battery and first body earth point - 0.01v,
Voltage drop between first body earth point and engine block - 0.17v,
Voltage drop between bolck and alternator housing - 0.06v.

As well as the above I removed fuse 6 and tested voltage across te connectors with the engine running and it read between 2.27v and 2.33v, I don't know what this should read but it at least points to the fact that it is receiving power.

I also checked the under bonnet fuse box and pulled each fuse, finding that fuse 34 had failed so I replaced that. I also pulled all relays to check for scorching and could find no tell tale marks. The fuse box did have a burnt electrical smell but I think that may have been the 25 amp fuse blowing.

So, with everything I've read so far I'm thinking it may be that the alternator is now too weak for the battery and is assisting in the gearbox fault and possibly a bad earth somewhere. What do people think?

Any help will be greatly appreciated.

Thanks,

Andy.

First guess is a duff fuse box as you said you fouls smell burning.

Engine running at 2k rpm you should get around 14.2v

Yeah, that is one of the other things I was thinking about but it's strange that it hasn't thrown any other faults up other than the fuses under the drivers seat.
Cheers,
Andy.

Alternator is duff by the sound of it, note the volt drop on load. you should be seeing 14.2 volts at 2K rpm.
Any smell of burning and the fuse box is also likely to be fubarred.

Cheers Datatek, I'm thinking the same thing with the alternator. With regards to the fuse box, do you not think the smell could have been the 25 amp fuse blowing in F34? Should I not see any tell tale scorch marks if the fuse box has had it?
Cheers again,
Andy.

B16FUN said:

Cheers Datatek, I'm thinking the same thing with the alternator. With regards to the fuse box, do you not think the smell could have been the 25 amp fuse blowing in F34? Should I not see any tell tale scorch marks if the fuse box has had it?
Cheers again,
Andy.

Click to expand...

One fuse blowing shouldn't leave much of a smell.

The problem with these fuse boxes is that it is a multi-layered board so you could have issues without being able to see anything. If it smells then bite the bullet and replace it, it's probably the original anyway.

Cheers Dogsbody. Well, I have removed and stripped the fusebox apart as far as I can and can see no damage visualy although I know I have not been able to seperate the two halves of the board. I did however notice cracking along the folded edge. I took some pictures here;
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I have put it all back together again and reconnected the battery and it still ha the same gearbox fault along with the three fuse failures.
Cheers,
Andy.

You'd do well to get plugged in to one of the fault reader/clearers, clear these faults (hopefully) and then see if they re-appear.

Cheers for that Dogsbody. I'll look to get them cleared, on question, if I have the gearbox fault code cleared will it take it out of limp home mode or will that remain until I change the alternator? I only ask as I won't be able to do the alternator until at least next weekend but my wife needs the car through the week.
Cheers,
Andy.

no fault = no limp mode











mind you it is a P38 !!!!!!!!

B16FUN.

I had a big fuse blow last year due to d defective EAS pump. The smell of the fuse blown lasted weeks before it finally went.

I was paranoid about 'other' electrical faults durring that time.

Take a cup of tea and look, look and relook around the fuse boax area with a torch to try and reasure yourself.

regards

B16FUN said:

Cheers Dogsbody. Well, I have removed and stripped the fusebox apart as far as I can and can see no damage visualy although I know I have not been able to seperate the two halves of the board. I did however notice cracking along the folded edge. I took some pictures here;
Image hosting, free photo sharing & video sharing at Photobucket
I have put it all back together again and reconnected the battery and it still ha the same gearbox fault along with the three fuse failures.
Cheers,
Andy.

Click to expand...

If the alternator is duff you can get all sorts of fault codes up.
As far as can be seen from you photo's your fuse box is OK.

Cheers Datatek and Donp38. The local Land Ranger Services here in Stockport said they'd have a quick look at it tomorrow to confirm if it is the alternator or not and they're doing it for free, bloody decent guys Simon and Pete are.
I'll keep the post updated to it's conclusion as my biggest bug bear on forums are threads where people post problems, people suggest fixes and you never hear if it worked or not, it doesn't help the rest of us!
Cheers,
Andy.

Right, well, this morning as my wife was about to take the Rangie to Land Ranger Services the gearbox fault cleared itself along with the fuse failures and the Hevac unit is back on and the suspension height indicator lights and gearbox indicator lights all came back on as if nothing had happened. Still took it to Land Ranger and they have checked over everything today, battery, alternator, etc, etc and could find absolutly nothing wrong!?!? I will obviously keep an eye on it and if it hapens again, try to figure out what had happened. Cheers for all your help guys, sorry I have no proper conclusion to share.
Andy.

Well, this intermitant fault has come up a couple of times since my last post. I put a new battery on it at the weekend due to the old one going flat last week with the cold weather. It has gone into the Gearbox limp home mode again along with the Hevac system being off - no power, EAS height indicator lights being very dim, gear shifter selection lights very dim, no brake lights and when you do press the brake the dim lights on the EAS and selection lights go out completely. Really getting frustrated with this now as it really detracts from owning the car and being intermitent you never know when it'll do it or why. It says Fuse 6, 7 and 17 have all failed, which they haven't. Anyone any suggestions? Alternator was checked and said to be fine by Land Ranger Services when they had it in last.
Do people think the fusebox is knackered and if so, the one under the bonnet or the under seat box? I ask that because the three fuses it says have failed are the ones under the seat but it seems from my searching on here that the one under the bonnet can cause similar issues to the one's I have.
Any help would be appreciated!
Cheers,
Andy.

+1 for the fusebox....

Any dampness on the floor??

Not on the drivers side. Sometimes on the passenger side but I think that's the drain for the heater inlet blocked.

+2 for the under bonnet fuse box.

Well guys, I've just changed the under bonnet fusebox for a good, known to be working used one from my local breakers and....... no joy. Still has the same Gearbox fault message (it's in limp home mode, locked in 3rd gear when put into D or any other forward gear and won't change over to high/low box), fuse 6 failed, fuse 7 failed, fuse 17 failed, Hevac power off (completely), dim EAS height indicator lights (EAS still works and goes up and down as it should on the switch), dim Gear selector lights, no brake lights. So, BECM, maybe? Other than that I may well torch the thing as I'm loosing patience with it. I've changed the engine, glow plugs, ABS pump, ABS modulator block, full brake fluid change,m new n/s front brake caliper, retrimmed head lining, full auto gearbox oil change including filter, replacement engine oil cooler and now a replacement under bonnet fuse box. Really, really fed up with it now.