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guineafowl21

Well-Known Member
Hi all,

Just bought an 04 Td4 S facelift to replace our high mileage 02.

The instrument cluster appears to have some blown 'bulbs', which on inspection appear to be surface mount LEDs. I'm quite happy to have a go at sourcing and replacing these, but not sure how to get at them.

I think I need to remove the pointers for the rev counter, speedo etc, but I can't see how and I don't want to break them. My questions are:

1. Has anyone removed the pointers, and if so how?
2. Where can I get some LEDs from, and do they have to be specific colours?

I realise I could send the unit off for repair, or even get a replacement, but I'd rather just replace the LEDs if I can.
Cheers
 
I tried to do this; Total disaster. Ended up with a replacement cluster. I dont remember taking the needles off, but if you do need to, two teaspoons used as prybars under the hub will pull them off.
iirc my soldering iron couldnt put enough heat into the right spot quickly enough to melt the solder and holding it there too long damaged the LED.


Its unlikely the LEDs just "blow", more likely they have been sabotaged to hide fault lights, as mine had. When I put the new cluster in I suddenly had various warning lights.
 
dave21478 said:
I tried to do this; Total disaster. Ended up with a replacement cluster. I dont remember taking the needles off, but if you do need to, two teaspoons used as prybars under the hub will pull them off.
iirc my soldering iron couldnt put enough heat into the right spot quickly enough to melt the solder and holding it there too long damaged the LED.


Its unlikely the LEDs just "blow", more likely they have been sabotaged to hide fault lights, as mine had. When I put the new cluster in I suddenly had various warning lights.
Click to expand...
Thanks Dave.

I pulled the needles off as you suggested - worked!

The LEDs don't show any evidence of sabotage, but I see your point. Did you buy a new cluster, or a secondhand one?
 
Also, were did you get the LEDs from? I can find loads on RS online, but not the right size. Not sure of the working voltage either.
 
Crazy LED's up in the north east is a good person to talk to, he knows is stuff with smd conversions and reapirs
 
I got a second hand cluster in the end.

I de-soldered LEDs from a scrap panel from a different Rover car. Maybe things would have gone better with new ones, but like you I didnt know what spec they should be and most places like aliexpress only sell loads of 50 or so.
 
I discovered I had my amigo LEDs plus handbrake led butchered by the previous owner. I replaced the LEDs with standard 12v ones, didn't mess about with surface mount. Was difficult getting the iron in place but managed. If you try it yourself, little tip: use blu tack to hold the led body in place while you solder, gives you an extra "hand".
 
Kayos said:
Crazy LED's up in the north east is a good person to talk to, he knows is stuff with smd conversions and reapirs
Click to expand...
Thanks Kayos (and Dave). I spoke to crazy LEDs and he gave me some guidance on diagnosing the board. There is a group of LEDs that has failed and they share the same power supply, but unfortunately I can't trace the fault. I've put a new thread up asking if a YAC501140 cluster (from an 06) will swap for my YAC500950. I don't suppose either of you know?
 
landyhaze said:
Photos? If you can trace a circuit I might be able to help...
Click to expand...

Hi Haze,

The pic below shows the LEDs that don't work (that I know of). They appear to be switched by the cathode side, are mostly yellow, and share an anode supply which converges on the resistor on the right, labelled R97 and marked 361. Its resistance is indeed 361 ohms. The track then disappears below the LCD screen and I can't trace it beyond that.

All the 'faulty' LEDs light up with an external 3V supply of two AA batteries in series.

Cheers
 
Sorry, here it is:

image.jpeg
 
Looks like you are getting there. So all the 'unfunctioning' LEDs are infact OK? My guess would be all the LEDs on the PCB are grouped through a few anode 'feed' resistors like R97. I would try to see if there are any other 'feed' resistors. Then try to power the PCB up on the bench. Most automotive instrument clusters will do a 1 or 2 second bulb test at power up and that should be good enough to allow you to trace all the feeds. Either the +ve feed on R97 is absent, or less likely the CPU is somehow not able to pull the cathodes of the LEDs low. You should be able to figue this out by metering the voltages on R97 and the LED anodes during the 1 second bulb test.
Good luck
 
landyhaze said:
Looks like you are getting there. So all the 'unfunctioning' LEDs are infact OK? My guess would be all the LEDs on the PCB are grouped through a few anode 'feed' resistors like R97. I would try to see if there are any other 'feed' resistors. Then try to power the PCB up on the bench. Most automotive instrument clusters will do a 1 or 2 second bulb test at power up and that should be good enough to allow you to trace all the feeds. Either the +ve feed on R97 is absent, or less likely the CPU is somehow not able to pull the cathodes of the LEDs low. You should be able to figue this out by metering the voltages on R97 and the LED anodes during the 1 second bulb test.
Good luck
Click to expand...
If I could power up the board on the bench that would be a great help. Do you have any idea where I could find a pinout diagram?

Also, I see there are points on the board marked 'test 3' and so on. I assume these are diagnostic points, and that somewhere there's an engineer's flow chart to trace faults. Where would this information be?
 
You should be able to get the wiring information from the "RAVE" disk. There are .ISO images available, try the LandyZone search box at the top of the page. The wiring manual will show pictures of the various connectors, you just need to figure out which ones are 12v, GND, and ignition.
 
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