I have a 09 plate X type estate that when I purchased it had only 50 % of the LEDs working on the instrument cluster. The garage Ii got it from failed to solve the problem. A second instrument cluster from another vehicle was fitted and 100% of the LED's were illuminated, however not at an acceptable level of illumination despite the dimmer being at maximum. At full brilliance position they appear to be at minimum brilliance....My local JAG independent garage swapped over the panel that contained the dimmer in it from a known working vehicle but this did not change things at all on max position of this switch the cluster LED's were the same - barely visible. Heater and radio lighting appears normal and does dim down if I should alter the dimmer to minimum which would mean NO cluster lighting at all. Frustrated to Hell with the lack of acceptable Instrument cluster lighting - especially at night when you really do need to see your instruments. The second cluster had to have the mileage corrected and the guy that did this said he thought there might be an Earthing issue??? Any ideas would be gratefully received...

Bryan

Southampton

 

I second the earthing problem, although it might well be a different line with a bad connection.

Our lights are dimmed by an electronic process known as "pulse width modulation"; there is an underlying signal that will provide a low level of illumination, the PWM signal comes up from the dash light drive circuit and is split in two; one branch goes to the radio/climate lights, the other goes to the dash.

A faulty earth can keep the PWM signal from ever getting to the LEDs. It may be as simple as touching up the soldered connections on the display.

 

a2bcg, lets do some simple checks to see where the problem may lie. Lets first start with watching the steering wheel lights. When it is dark, adjust the dimmer on the headlight switch to adjust the brightness of all the dash lights. Be watching the steering wheel buttons. Do they become fairly bright when turned all the way up or do they remain pretty dim, even on the highest setting?

If the steering wheel is bright, but the instrument cluster is dim, then we know the dimmer circuit is good. If this is the case, then you will need to access the back of the instrument cluster and measure between pin 8 (black wire) on the cluster to chassis ground. You should get under 1.0 VDC with the lights on as bright as they will go. If you are getting over that, then you have a bad ground wire and will need to troubleshoot that wire. May want to also look at the connector and see if pin 8 is discolored (have a dark, caramel look to it instead of a shiny, golden color, possibly silver).

If all of your lights are not becoming very bright, then you will need to access the back of the headlight switch or the cigar lighter. You are looking for the orange wire. With the dimmer at max intensity, what voltage are you getting? You should be getting 12 VDC. If you are down around 6 VDC, then you have a bad dimmer circuit.

A little more detail about how the dimmer circuit works. Like what wa3ra said, it is a pulse width modulation setup. In short, it is turning the lights on and off very fast (around 100 times a second as I recall). This is fast enough that you eyes just see the light and no flicker. What the dimmer is then doing is changing the amount of on and off time. The more on time compared to the off time, the brighter your eyes will think the light as (your eyes average the light intensity when you look at something) So, if you have very little on time compared to off time, our eyes will see the quick on brightness, but then average it with the long off (dark) time, leaving you with a dim appearing light.

 

Gentlemen

Thank you both for your very valuable information. I will wait until it gets dark and go and see what happens when I carry out your investigative suggestions.

Bryan

 

Very interesting and informative. I learn something every day!

This is very similar as to how our brains see video. I think it is something like over 30 frames (pictures) a second and our minds see it as nonstop motion or a moving video. Remember how you made the flip drawings as a kid

If I may ask a question Is there to block the pulsing to the radio/climate lights as I can not read the display at night when they dim?

 

Larry, what you would have to do is to essentially cut the wire between the radio and the lights. This should cause the radio to no dim at night as it will think it is still day out and you have not turned on the lights. If you need more info, let me know and I will investigate it further.

 

Hi "Thermo",

If you would be able to tell me the wire at the light switch, I will give it a try. I was thinking it was much harder.

I like EZ stuff

 

larry, if you pull the radio out of the dash, what you will need to find is the orange wire going to pin 17. This is the wire you will need to cut (cutting it else where will affect more lights than you may want affected). The end of the wire going back to the harness in the dash you will want to insulate the end of to prevent future issues. The end going to the radio, you will want to add a butt splice to that wire. You will then add a new wire to the buttsplice and extend it through the dash to the central junction box. You will want to find a piece at your local auto parts store called a fuse tap. This will allow you to pull out fuse F97 (feeds your glove box and side light status on the instrument cluster) and install this in its place. You can then reinstall fuse F97. Take the wire coming off the fuse tap and butt splice that to the wire coming from the radio. The radio lights will now get full voltage (and therefore light) any time the lights come on.

Should be able to do this mod for under $10 and probably an hour of your time.

 

Hi Guys
I have been a little pre-occupied with my Jag as sustained some damage to the vehicle in a recent storm when a tree branch fell onto the roof and front windscreen, dented the roof just by the top of the screen and shattered the screen. It could have been worse and I was not injured but had the fright of my life when driving the vehicle not expecting this to happen. Will be an insurance claim to get the screen changed and body work repairs to the roof and bonnet...
However I have had a chance to carry out some further investigations following the very helpful advice given. It is this :- When carefully watching the steering wheel lights and altering the dimmer switch these lights dim down with the climate and radio panel as well as the mileage/trip info panel in the cluster. Along with this dimming the instrument cluster also goes down to a very low illumination. Moving dimmer switch to max all lights come back up to full levels with the EXCEPTION of the instrument cluster lights meaning that Tacho, Speedo, Fuel Gauge and Fuel gauge are practically unreadable in the dark. I believe then it is has been established that he dimmer circuit is functional and that the fault does now indeed appear to be elsewhere and an earthing/poor connection?

 

Hi there from a newbie. Recognise this is an old thread, I’ve just bought a lovely 2009 x type and unfortunately it’s got similar problems to a2bcg. At night with the dimmer set to max brightness, everything is nice and bright except the actual gauge faces. The faces are so dim they are barely readable despite the orange ‘hands’ being very bright. The dimmer circuit operates (its not at all smooth though) and everything dims in sync.

Any advice on resolving would be welcome. My plan of attack is currently limited to: remove the cluster, inspect & clean the rear connectors.

 

Worth a shot =

https://www.jaguarforums.com/forum/x...ee-fix-106913/

Heed post #11 =

https://www.jaguarforums.com/forum/x...ulb-off-74723/