P38 4.0 SE 1997 - Unknown item - info requested!

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P38 Monkey said:
As ever, very valid. In retrospect I should not have started to make this km/h to mph conversion, but now might as well follow through. Just waiting for my mph eBay instrument module to make its way through the Royal Mail strikes etc.
I was reworking the panels around the steering anyway, as they are all damaged. The previous (Japanese) owner had fitted a lot of inscrutable electronic devices, hacked the wiring about, and seriously damaged every single trim panel. I think they must have been using an LR Series toolkit (mole grips, monkey wrench, ball pein hammer).
The tyres on my P38 are oversize, so the speedo will probably have a 5% or so error one way (under reading the speed), and whatever JLR designed the other way (over reading)..
Then there's what the BeCM and the speedo discuss between themselves, and agree the speed to actually be displayed.
I'll have to see what the calibration looks like when I have installed it and if necessary just go back to km/h...as ever, learning more about my P38 every day.
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The DigiHud app on an Android phone or tablet will give you a very accurate actual speed reading to show what error you have.
 
Datatek said:
I think you will find that the needle calibration is different. I have one with MPH and one with KPH and 30mph is not in exactly the same place as 50kph.
I think that if you change KPH to MPH in the BECM that the kilometers logged will become miles logged so showing a false reading, I have never had the courage to try it but as far as I can see, there is no facility in the BECM to do the maths to make the conversion as it is not something that is needed.
I actually do not see the problem, I run an mph speedo in Europe and have no problem remembering the speed limits in mph. For my wife, I use an app called DigiHud to display the speed in kph on her phone
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I **think** that is what happened to Brian. It always goes with the highest number from either BECM or cluster. Changing the kph to mph only changes the BECM as I think that is where the units are held. The dash will go to the higher number and then you cannot get it back down without a Faultmate. I guess if you take pictures before and after or maybe take it for an MoT test before and after then you can prove the mileage.
 
Grrrrrr said:
I **think** that is what happened to Brian. It always goes with the highest number from either BECM or cluster. Changing the kph to mph only changes the BECM as I think that is where the units are held. The dash will go to the higher number and then you cannot get it back down without a Faultmate. I guess if you take pictures before and after or maybe take it for an MoT test before and after then you can prove the mileage.
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Either the cluster OR the BECM will go to whichever holds the higher mileage/kilometrage when the cluster is changed. The BECM doesn't distinguish between Km & miles, it simply applies a different algorithm to make the calculation using the data from the ABS sensors then stores the result in memory and also sends the result to the cluster.
 
brianp38dse said:
That motor is one of the blend motors that should be on the heater unit, there are three one each side for the temp and one in the center for the distribution of the air.
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There is one already fitted to that side of the heater matrix, so it might be the RHS recirc servo. I need to work out where that would fit - somewhere under the right hand end of the dashboard I assume...?
 
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will this help
upload_2022-10-29_13-53-30.jpeg
 
Datatek said:
The DigiHud app on an Android phone or tablet will give you a very accurate actual speed reading to show what error you have.
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+1 on DigiHUD - Use it with Otto as he appears to read accurate to 25 mph, and above about 65-70mph, but between his is about 5mph slow on the speedo compared to DigiHUD, useful to know with speed cameras about!. DigiHUD doesn't seem to be heavy on battery either.
 
Scotiawhiskers said:
+1 on DigiHUD - Use it with Otto as he appears to read accurate to 25 mph, and above about 65-70mph, but between his is about 5mph slow on the speedo compared to DigiHUD, useful to know with speed cameras about!. DigiHUD doesn't seem to be heavy on battery either.
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Odd. Compared to my Garmin GPS my speedo is barely more than 2mph out at any speed. I'm always amazed as the Jag is nowhere near as accurate.
 
Grrrrrr said:
Odd. Compared to my Garmin GPS my speedo is barely more than 2mph out at any speed. I'm always amazed as the Jag is nowhere near as accurate.
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Vehicle speedometers seem to be all over the place these days, on my Xtrail, the speedo over read by 8kmh so at 50 kmh indicated it was actually travelling a 42kmh.
 
Here's an update on my speedo kph-to-mph mini project - now completed and lessons learned!! A cautionary tale...
It all started with a minor change - the "I" button on the indicator stalk was broken and annoyingly kept falling off.
So I thought while I was at it, I would swap all the broken panels in the steering column area and change the speedo from (Japanese) kph to mph.
Warning 1: don't think you can take off the instrument needles and fit an mph back plate. The "official" way of removing needles is to insert two teaspoons under the head of the needle and lever down on the handles. From my experience, this does not work on P38 instruments: those instruments will never work again.
Warning 2: as per previous listings, connecting another instrument pack will cause the BeCM to throw a wobbler, flash up "odometer error" and subsequently take the highest reading of the two.
My solution was to buy a used (working) instrument pack for £20+post on eBay, take off the front covers, then removed the rear cover.
There are "static" warning stickers on it, so best completed in a cold clean slightly damp garage, not in your warm too-dry house with that nylon shag-pile carpet you got in the 1970's.
Under that back cover, the instruments are connected by 3x screws each, with the speedo/tacho connected together of course.
Conveniently, the connections to the instruments are actually made by the fixing screws, so no extra wiring.
Taking the individual instruments out like that is just moving the mechanical parts across, so the BeCM is unaware of the change.
The result is a speedo in mph, with the odometer (and trip meters) still in km and showing the correct original figure. Mph speedos have a perfectly legible (and back-lit) kph scale too, which is handy.
The consumption shows in litres per 100km, but you really don't want to look at that anyway.
End result is 1-2 mph over-reading vs GPS (eg 40 on speedo is 39 on GPS), which is as accurate as you need (and better than most).
 
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@pwood999

I have seen a few like that, and I am sure it's possible but am not going to say anything about doing it as I dont know enough about it.
Also, there is the KMs to Ms issue. Sure:), that can be taken care of but is it DIYable.

Not the sort of thing I would discuss in an open forum, but it is out there;).

J
 
pwood999 said:
Dunno if this actually works, combined with Market change in BECM it might be possible to get the correct mileage ?
https://www.landyzone.co.uk/land-rover/i-thought-this-was-impossible.126322/#post-1288378
Certainly not gonna try it myself !!
View attachment 277600
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Me neither - looks very dodgy and uses typical spam email wording.
I am happy with an mph+kph speedo, a km (original) odometer, and a relaxed happy BeCM.
Thought worth posting the needles removal problem and the way around it, which worked for me.
 
P38 Monkey said:
Me neither - looks very dodgy and uses typical spam email wording.
I am happy with an mph+kph speedo, a km (original) odometer, and a relaxed happy BeCM.
Thought worth posting the needles removal problem and the way around it, which worked for me.
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The guy in the link is actually very clever from what I gather and being (boss?) of BBS they have done huge for the LR community, why he left this forum I dont know.

J
 
marjon said:
The guy in the link is actually very clever from what I gather and being (boss?) of BBS they have done huge for the LR community, why he left this forum I dont know.

J
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Oops - my apologies. But unsoldering and replacing a 1990’s PROM is not for the faint hearted. I’ll mentally file it alongside all that “top hat” stuff. Hopefully just happens to other people’s P38s…
 
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