I'll bet the 9v is down to a dodgy cable/connection..
P38 Monkey
Well-Known Member
Clean and simple terminal fitting. Note that the terminal is fitted well down on the battery post. Oh dear, once again stating the obvious.
Datatek
Well-Known Member
The earth from the engine to chassis may not be a cable but a flat mesh.
Datatek
Well-Known Member
On the diesel, there are several wires going to the battery + post.
P38 Monkey
Well-Known Member
That photo is my son’s 1965 Triumph - my Range Rover is in intensive care right now (V8 Developments)… But the principle is of course the same. As ever, there is more to go wrong in a P38.. And if it can, it will…!!
Datatek
Well-Known Member
The connections on my 1986 MR2 are much the same as the Triumph.
So where were we.....
I have changed a couple of things, and I think I've cracked it.
First up is changing the coil packs with another set I had.
Then I changed the gearbox ECU with a cheap replacement from eBay.
Dissasembled and cleaned all the earth cables from the battery to the body etc.
Firstly changing the coil packs has made it run a load better, and the power is back... I think this was the cause of loss of power under load TBH.
Secondly the gearbox is changing as it should, kickdown is there so it's much easier and smoother to drive. It's not getting bogged down at the hill and grumbling up it, but changing down and drives up as you'd expect.
I think we can call this a win!
Comparing the voltage at the gearbox ECU this is back to normal. My old ECU was still showing sub 9 volts even though there was 11.7 volts on the pin. My new used one from eBay is showing 11.7 volts on the Nanocom with 11.7 volts at the pin. So that's looking much healthier.
Cleaning up all the earths hasn't made any difference to the voltage at the gearbox ECU, but I'm going to fit new cables there when they get delivered. I'll also probably get some new coil packs and fit them so they're new.
Does anyone know the difference between the gearbox ECU part numbers? I had an AMR5494, and that's what I ordered off eBay, but what I got was an AMR5496. I've fitted it anyway, and it seems to work.... It looks like it's just hardware and firmware updates, but I'm not sure. I could send it back I suppose.
I have changed a couple of things, and I think I've cracked it.
First up is changing the coil packs with another set I had.
Then I changed the gearbox ECU with a cheap replacement from eBay.
Dissasembled and cleaned all the earth cables from the battery to the body etc.
Firstly changing the coil packs has made it run a load better, and the power is back... I think this was the cause of loss of power under load TBH.
Secondly the gearbox is changing as it should, kickdown is there so it's much easier and smoother to drive. It's not getting bogged down at the hill and grumbling up it, but changing down and drives up as you'd expect.
I think we can call this a win!
Comparing the voltage at the gearbox ECU this is back to normal. My old ECU was still showing sub 9 volts even though there was 11.7 volts on the pin. My new used one from eBay is showing 11.7 volts on the Nanocom with 11.7 volts at the pin. So that's looking much healthier.
Cleaning up all the earths hasn't made any difference to the voltage at the gearbox ECU, but I'm going to fit new cables there when they get delivered. I'll also probably get some new coil packs and fit them so they're new.
Does anyone know the difference between the gearbox ECU part numbers? I had an AMR5494, and that's what I ordered off eBay, but what I got was an AMR5496. I've fitted it anyway, and it seems to work.... It looks like it's just hardware and firmware updates, but I'm not sure. I could send it back I suppose.
Datatek
Well-Known Member
All I know is that the auto box ECU for the diesel is different to the 4.6. The 4.6 is I believe CAN bus and has resettable trims.
It's all a bit of a conundrum. Those part numbers are listed on Microcat for the P38 just for differing VINs. All for the GEMS though, it changed properly for the THOR.
Black Cat Solutions only list the AMR 5494 (with software revision GS2.38) as the only ECU used on the P38, but AMR5496 (with software revision GS2.12) is clearly a P38 part, but only used for one year of manufacture. VINs that start TA.
Anyway, the eBay guy has agreed to send me the correct part, so it'll all sort itself out.
Black Cat Solutions only list the AMR 5494 (with software revision GS2.38) as the only ECU used on the P38, but AMR5496 (with software revision GS2.12) is clearly a P38 part, but only used for one year of manufacture. VINs that start TA.
Anyway, the eBay guy has agreed to send me the correct part, so it'll all sort itself out.
You should also check if the Auto Box ECU is set for the correct engine size. It's on the last page in the settings I think.
I would assume later software "should" be better ? Part numbers could simply be factory references for 4.0 vs 4.6 settings so factory workers don't need to set it.
I would assume later software "should" be better ? Part numbers could simply be factory references for 4.0 vs 4.6 settings so factory workers don't need to set it.
That was my thought. Later versions may have slightly different settings to may smoother gear changes and possibly help mpg figures.
Getting second-hand coil packs off eBay and fitting them to a newly refurbished engine wasn't a clever idea. I'd never fit second-hand coil packs or spark-plugs or leads for that matter. I'm not entirely sure what the thinking was there.
Shows these cars don't like to be left standing for over a year though. The damp gets in everywhere and then stuff just starts breaking down.
No one did that though.
The coil packs were the original ones from that engine, and worked perfectly before they sat for a year. The rest of the stuff was brand new less than 2000 miles ago.
Back in your box cowboy.
The ones that have gone back on? Where did the dodgy ones cone from?
Okay, so I've added an extra positive cable direct from the alternator to the battery +, also added another earth strap from the battery - to the engine block, cleaned all the earths up, and retightened everything. I now get 14.4 volts at the battery with the engine running. I deffo had earthing problems.
Regards the gearbox ECU, the eBay seller that sent me the AMR5496 ECU in error, also send me another correct AMR5494 to replace it with, so that was very good of him.
The "other part number (AMR5496)" gearbox ECU now shows 14.4 volts on the Nanocom and also I get 14.4v on the pin. The "correct part number (AMR5494) is now showing 12 volts on the Nanocom, even with 14.4v on the pin. I've tried both my original and replacement AMR5494 and they both show 12v on the Nanocom even though that's not what is on the pin. Gear change is back to normal though, so I think that might be a software bug with the voltage reporting to the Nanocom...?
I think the bad earth was causing my original gearbox ECU not to work properly, rather than the ECU being duff.
Either way, sorting the earthing out has sorted the gearchange, that and a new ignition coil pack has transformed the car. I'll book it in for an MOT this week and we'll see what we see......
Regards the gearbox ECU, the eBay seller that sent me the AMR5496 ECU in error, also send me another correct AMR5494 to replace it with, so that was very good of him.
The "other part number (AMR5496)" gearbox ECU now shows 14.4 volts on the Nanocom and also I get 14.4v on the pin. The "correct part number (AMR5494) is now showing 12 volts on the Nanocom, even with 14.4v on the pin. I've tried both my original and replacement AMR5494 and they both show 12v on the Nanocom even though that's not what is on the pin. Gear change is back to normal though, so I think that might be a software bug with the voltage reporting to the Nanocom...?
I think the bad earth was causing my original gearbox ECU not to work properly, rather than the ECU being duff.
Either way, sorting the earthing out has sorted the gearchange, that and a new ignition coil pack has transformed the car. I'll book it in for an MOT this week and we'll see what we see......
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Datatek
Well-Known Member
The Nanocom is reading the voltage via the wiring and connectors so will often show a lower voltage due to volt drop in the wiring and connectors.
Yes, but why would it jump 2.4 volts between the other part number and the correct part number? Both are using the same connectors. And both “correct” part numbers show the same “wrong” voltage.
It’s got to be something about those ECUs hasn’t it? Unless they’re both duff.
Datatek
Well-Known Member
That I do not know unless there is more than one live feed and that pin is unused on the other part number. It's also possible the the components in the ECU draw less power but I can only guess.
