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KMH to MPH Instrument Cluster Swap

Ballard
Posts: 77
Joined: Wed Aug 29, 2018 9:19 pm

Re: KMH to MPH Instrument Cluster Swap

Postby Ballard » Mon Sep 03, 2018 7:46 am

Yes, my car is from Japan and the speedo only displays kph, annoyingly.

abercanadian
Posts: 1281
Joined: Tue Oct 16, 2012 6:50 am
Location: Vancouver Island

Re: KMH to MPH Instrument Cluster Swap

Postby abercanadian » Mon Sep 03, 2018 7:52 am

Cluster is just a bunch of plastic, dials, LCD's and bulb slots. No eproms chips etc so nowhere to store anything except dust. :D

Larry

p.s. not so sure that the kilometer total "mileage" (!) display is switchable via the km/mph switch on the panel ..I know trip etc translates, check that the main display switches back and forth ...if it does, you should be all set.
Image
94 XJ40 VDP vin 701729
Oyster Metallic/Doeskin on Aero Alloys
230,000 Kilometers 143,000 Miles
Daily Driver

94 XJ40 SOVEREIGN vin 703632
Diamond Blue Metallic/Barley
111,000 Kilometers/69,000 Miles
Parts Car

Ballard
Posts: 77
Joined: Wed Aug 29, 2018 9:19 pm

Re: KMH to MPH Instrument Cluster Swap

Postby Ballard » Mon Sep 03, 2018 8:09 am

Odometer mileage reading is KM and can't be changed to miles with the switch, I've tried.

I thought the EPROMs etc were within the cluster but I hope you're right.

abercanadian
Posts: 1281
Joined: Tue Oct 16, 2012 6:50 am
Location: Vancouver Island

Re: KMH to MPH Instrument Cluster Swap

Postby abercanadian » Mon Sep 03, 2018 9:02 am

The only way to change to miles would be with an GB or USA ECU swap together with a cluster - plus - if it's a Japanese market car there would be other idiosyncrasies you'd have to deal with, IMHO better to just get a gps, use that and put up with kilometers. :?

BTW, where did you hear that the mileage was stored in the cluster?

Larry
Image
94 XJ40 VDP vin 701729
Oyster Metallic/Doeskin on Aero Alloys
230,000 Kilometers 143,000 Miles
Daily Driver

94 XJ40 SOVEREIGN vin 703632
Diamond Blue Metallic/Barley
111,000 Kilometers/69,000 Miles
Parts Car

pimgmx
Posts: 3279
Joined: Tue Jul 08, 2014 12:07 pm
Location: South East of the Netherlands

Re: KMH to MPH Instrument Cluster Swap

Postby pimgmx » Mon Sep 03, 2018 9:26 am

abercanadian wrote:...mileage is recorded by the ECU...

The XJ40 has several electronic 'control boxes' on board (gearbox, ABS, engine, body control unit), but none of those store mileage.
An approach unlike more modern - ie late '90s - cars, where mileage is stored both in the instrument cluster AND one or more ECUs, to avoid odometer tampering.

The gremlins on my Sovereign a few years ago forced me to test-swap most of those components (engine ECU, body control unit), and none of those impacted the reading on my odometer.

Just for the heck of it I just grabbed a spare instrument cluster from ye olde parts shed and removed (4 tiny phillips screws) its back panel: that big Lucas microchip could very well be the place where mileage is stored...

Image

Working on that spare instrument cluster made me think about one other workaround for Ballard's question, but that requires patience and bravery in equal portions. :roll:

You could remove your car's cluster, pop out the Plexiglas front (it's merely clicked into place), and then gently remove the gauge needles in order to swap the fascia only with one from a UK market donor item...

Removing/refitting gauge needles is not for the faint of heart; I'd suggest to practice on a donor item before applying that type of surgery to your car's original parts!
Last edited by pimgmx on Mon Sep 03, 2018 10:05 am, edited 2 times in total.

the daily: 01 S8 http://bit.ly/2kIwP4m
the tractor: 77 LaRo LW https://bit.ly/2Hr9n6y
the eyecatcher: 93 Insignia http://bit.ly/1iGrmsU
the GT: 89 XJS http://bit.ly/1WQGpC5
the project: 95 X306 http://bit.ly/1cW11DN
the pocket rocket: 97 Z3 http://bit.ly/12IfE7B
the ex: 93 3.2 http://bit.ly/14GTNrq

Ballard
Posts: 77
Joined: Wed Aug 29, 2018 9:19 pm

Re: KMH to MPH Instrument Cluster Swap

Postby Ballard » Mon Sep 03, 2018 9:34 am

I can't remember specifically, but from various forum posts etc. on the internet.

Also, second hand clusters on eBay are sold stating their recorded mileage because the sellers claim this is the mileage that will be shown when fitted to a new car. It's certainly very confusing.

I also noticed within the Jaguar parts lists that the trip computers aren't region specific which made me think that whether mpg is recorded as U.S. or imperial is determined by the cluster itself. The clusters on the other hand are region specific. There's KM, U.K. Mph, U.S. Mph and Japanese Km. Being Japanese my car records mpg in U.S. gallons rather that the imperial I am used to which initially made me think my consumption was worryingly lower than my old X300.

Ballard
Posts: 77
Joined: Wed Aug 29, 2018 9:19 pm

Re: KMH to MPH Instrument Cluster Swap

Postby Ballard » Mon Sep 03, 2018 9:45 am

Thanks pimgmx, that's useful information.

I had thought about the dial swap idea, but as you say it is rather daunting. I also found this option:

https://www.lockwoodinternational.co.uk/c1722.html

However that presents problems of its own and clusters are so cheap swapping dials over is probably a better idea anyway.

I think I am going to buy one of the new old stocks clusters from eBay and just fit that. If I can get the mileage corrected I will and if not I will live with the 'new' mileage. The advantage of this is I also get mpg measured in imperial, atleast I hope so. We shall see.

pimgmx
Posts: 3279
Joined: Tue Jul 08, 2014 12:07 pm
Location: South East of the Netherlands

Re: KMH to MPH Instrument Cluster Swap

Postby pimgmx » Mon Sep 03, 2018 10:04 am

That Lockwood modification looks like a cool solution but would still require you to remove at least one gauge needle.
I also (that's the cheap Dutchman in me ;) ) think it's not great value: their 60 quid would buy you an entire used cluster, giving you the advantage of practice material AND free donor light bulbs. 8-)

Your 'let's just get a donor item and give it a try' approach sounds like the most sensible to me.

I think your board computer theory makes a lot of sense: afaik the engine and body processor ECUs only count 'sensor units', which are then translated to real-world values (US/UK gallons, liters, kms, miles) further down the chain. In that case it makes sense this happens on a market-specific level, like the instrument cluster. Maybe something our resident electronics gurus (yes, you Norman! :lol: ) can confirm?

- UPDATE -
Another route I haven't tried (yet) would be to separate front (gauges & fascia) and rear (PCB and bulb holders) halves of the instrument cluster: it looks like they're simply connected through the 3 flat cable connectors in my pic and this could be an easier swap?

For this Frankenstein scenario there's one big unknown, though: will the two different cluster halves be able to communicate, or is there something stored/configured on either half that prevents this transplant scenario??

And given assumptions on board computer output: is only the PCB part of the unit country/market-specific, or does that also count for the gauged front part? The first scenario would make most sense from a production efficiency perspective, but we shouldn't forget that we're talking Jaguar AND Lucas here... :lol:

the daily: 01 S8 http://bit.ly/2kIwP4m
the tractor: 77 LaRo LW https://bit.ly/2Hr9n6y
the eyecatcher: 93 Insignia http://bit.ly/1iGrmsU
the GT: 89 XJS http://bit.ly/1WQGpC5
the project: 95 X306 http://bit.ly/1cW11DN
the pocket rocket: 97 Z3 http://bit.ly/12IfE7B
the ex: 93 3.2 http://bit.ly/14GTNrq

Ballard
Posts: 77
Joined: Wed Aug 29, 2018 9:19 pm

Re: KMH to MPH Instrument Cluster Swap

Postby Ballard » Mon Sep 03, 2018 10:12 am

That's a very interesting idea, but as you say it's never wise to second guess the logic of Jaguar and Lucas.

I'll report back on how I get on with the new cluster.

pimgmx
Posts: 3279
Joined: Tue Jul 08, 2014 12:07 pm
Location: South East of the Netherlands

Re: KMH to MPH Instrument Cluster Swap

Postby pimgmx » Mon Sep 03, 2018 10:38 am

Since I won't need my donor unit any time soon (older model year than my current '40) I decided to rip it apart for the greater good and for my own amusement. :ugeek:

I think I have good news for you: there is NO 'intelligence' whatsoever in the driver-facing half of the gauge cluster!
That supports my 'you only need to swap the PCB' theory, making the KM/h-to-MP/h thing a very doable modification.
Remove the cluster back cover (6 + 4 screws), then the 8 phillips screws that connect the board to the plastic body and those 3 flat cables, that's all!

An illustrated story of my findings:

The white plastic frame that holds the gauge part of the cluster together is connected to the faux-wood fascia by seven (3 horizontal rows: 2-3-2) small phillips screws. The LCD also connects to the fascia panel (2 phillips screws) and links to the front side flexible board for signal input and backlighting (see further down).

The warning lights, dash illumination and gauges are all connected to one flexible board, seen on the picture below. This flexible board gets it juice & inputs through the three flat cable connectors on the main PCB.

Image

This flexible board has soldered clips (3 each) for the gauges that both supply gauge signal AND keep the gauges into place physically.
I removed the board by gently undoing those connectors/clips one by one, with this as result:

Image

With the fascia and board disconnected I could isolate the gauge units from the cluster, and 'prove' that there are no electronics there beyond the gauges themselves...

Image

And a shot from the front: you can see the separate gauge units with the fascia removed:

Image

Hope this helps,
Pim

the daily: 01 S8 http://bit.ly/2kIwP4m
the tractor: 77 LaRo LW https://bit.ly/2Hr9n6y
the eyecatcher: 93 Insignia http://bit.ly/1iGrmsU
the GT: 89 XJS http://bit.ly/1WQGpC5
the project: 95 X306 http://bit.ly/1cW11DN
the pocket rocket: 97 Z3 http://bit.ly/12IfE7B
the ex: 93 3.2 http://bit.ly/14GTNrq