Hi all, after my g/box rebuild (reverse band). Plugged in my Foxwell (with it in the auto transmission mode) to go through the oil level check procedure as per Rave. When the oil temp when reading 35-40 degrees I cycled through the gears a couple of times then checked the level but the reading for the (g/box) coolant was 105 degrees so I selected M47 engine on the Foxwell & the coolant temp was 87 degrees & the vehicles own temp gauge was half way as it should be, so I was wondering why the big difference in the coolant temps & has anybody come across/noticed this before, is it normal (it did reach 110 degrees when oil temp was 45,) ? Many thanks in advance.

Gday Andy, I used to have a Kv6 Freeelander until late2020 with the Jatco JF506E gearbox, and had changed the fluid myself without connecting scan tools via OBD.
I had a scan tool but the best it could do was coolant temp not auto trans fluid temps.

The kv6 is a large engine and would reach 105 degrees C as your stationary thus no air flow passing through the radiator as your carrying out this procedure. So long as the cooling fans come on at 105, I wouldn’t worry about it, as that’s what the system is designed to do to keep the engine cool. Once the coolant fans come on the coolant temp would fall.

That discrepancy is possible as coolant temps would be subject to higher temps due to needing to cool the large kv6 engine esp with nil air flow through the radiator.

The way I did it was, I took the kv6 for about a 15 min drive and brought it back and shut the engine off. I had a special temperature measuring device with a skinny cable about 2m in length with a tiny sensor at the end of it - I simply placed the skinny wire with sensor in through the auto gearbox fluid pan filler hole and as far down as it can go - it will reach the fluid and there’s your temperature. Then when it’s between 35 and 45 degrees C, turn on your engine and measure it again and if the correct temp is confirmed then go from there follow the rest of the procedure, the risk is that the skinny cable could get trapped in there, but if you carefully wriggle it you’ll be able to get it out.

Another method I used was getting a laser type temperature measure gun and simply undoing the same auto trans pan fluid filler cap, and pointing the laser through there which will come back with a reading, just ensure you strike the fluid with the laser.

And a 3rd method was undoing the level check bolt and once the fluid escapes, measure that with your laser thermometer and there’s your temperature.

I used all 3 methods at different times without issue.

Hi, my Foxwell scanner gives me the oil temperature (for level checking) no problem but it also gives the coolant temp presumably from a sensor in the JATCO & it's the high coolant temperature reading from that sensor that concerns me, as when I switch from the g/box menu to the M47 engine menu the coolant temperature is where it should be, 90 degrees along with the FL's temp. gauge sat at 12 o clock which is where its always sat. When I took it for its mot (12 mile round trip) the g/box oil temp was fine but the coolant reading was 129 degrees , flip back to eng menu & its 90 degrees !
So am I looking at a dodgy g/box sensor? What I would dearly like is if someone would kindly plug in their scanner & take some readings for me, say g/box fluid at 40 degrees then let me know what the coolant temp reads (from the g/box menu), mines reading 40 degrees(g/box fluid) & 105 degrees (coolant). Many thanks, all the best.

Andy Warren said:

Hi, my Foxwell scanner gives me the oil temperature (for level checking) no problem but it also gives the coolant temp presumably from a sensor in the JATCO & it's the high coolant temperature reading from that sensor that concerns me, as when I switch from the g/box menu to the M47 engine menu the coolant temperature is where it should be, 90 degrees along with the FL's temp. gauge sat at 12 o clock which is where its always sat. When I took it for its mot (12 mile round trip) the g/box oil temp was fine but the coolant reading was 129 degrees , flip back to eng menu & its 90 degrees !
So am I looking at a dodgy g/box sensor? What I would dearly like is if someone would kindly plug in their scanner & take some readings for me, say g/box fluid at 40 degrees then let me know what the coolant temp reads (from the g/box menu), mines reading 40 degrees(g/box fluid) & 105 degrees (coolant). Many thanks, all the best.

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Hmm… I’m going to run mine up later today, so can easily throw my PScan on it and take a look.
I know it can connect to the Jatco, just never had any need to look… assuming it has both temps, I’ll let you know by tea time!

Freddie17 said:

Hmm… I’m going to run mine up later today, so can easily throw my PScan on it and take a look.
I know it can connect to the Jatco, just never had any need to look… assuming it has both temps, I’ll let you know by tea time!

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Hi, thanks so much, I'll plug mine in later & take a pic of the scanner screen.

I don’t think you have anything to worry about - mine is the same (well, different also, as in temperatures!)
Each is clearly each reading something different, somehow… though I have no clue what/why.

This is immediately after a run just now, fairly warm day today too…

Engine ECU;
Coolant at 87* (gauge normal at 12 o’clock on dash & has the in-line stat mod fitted)
Temp gun showed this to be about right





Jatco ECU;
Coolant at 125* (!), and trans fluid at 64*

Hi @Freddie17 , can't thank you enough that's put my mind at rest after what was a 'long' job. As the XYZ switch mysteriously failed when it (the g/box) came back from from the reconditioners I was beginning to worry if something else had failed in their 'cleaning' process or if I'd left some workshop towel in a hose/pipe somewhere causing a blockage.
I replaced my stat in about 2018 with a oem one as I hadn't heard about the hose/stat mod at the time & touch wood I've had no issues since. I can now get it down to Hereford (taxing from Aug 1st) as I'm donating it to my son, think he's got a good deal 4x new Geolanders, 4x new damper/springs/gaiters & bump stops, 2 front lower arms powerflex bushes on all suspension links, new rear wheel cyl's/shoes & brake pipes plus stuff I've forgotten . Many thanks again & if I can make it to one of the green lane excursions I'll get you a beer,all the best.

No worries. I’ve had enough help on here - glad to return it

Your boy has indeed got a good deal!
I can vouch for the Geolanders too - cracking tyres for the price.

Stat should be good for a few years yet, and if he notices it not warming up and only going to 1/4 on the gauge, it’s a real easy fix. No need to touch the old one at all - takes an hour.

There's only the fluid temp sensor in the jatco. The auto computer may be aware of the coolant temp. But that will be via comms to the engine computer.

Hippo said:

There's only the fluid temp sensor in the jatco. The auto computer may be aware of the coolant temp. But that will be via comms to the engine computer.

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Wonder why it shows/picks up a different (hotter) temp to that of the actual engine ECU though?
Strange!

Freddie17 said:

Wonder why it shows/picks up a different (hotter) temp to that of the actual engine ECU though?
Strange!

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I fink the register location of the info is wrong. You get simular problems when using a hawkeye. Not all readings given are plausible.

Hippo said:

I fink the register location of the info is wrong. You get simular problems when using a hawkeye. Not all readings given are plausible.

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Not all readings given are plausible. I for one am glad about that .