Leon Instrument Cluster and Immobiliser

[Awingx]

I had the same fault and ended up sourcing a brand new, old stock cluster for £150 (SEAT wanted over £400) That then gave me the chance to troubleshoot the old one, without the worry of bricking it, and although I didn't test it at any great length, it definitely seemed to have sorted the problem when I took it out for a short test drive.

Basically I reflowed the 2 green and blue connectors that are circled in the attached pic. DON'T attempt it unless you're fairly experienced at soldering and feel capable of doing it without damaging the board or bridging the pins though!!
Use a suitable iron (I was worried about melting the plastic connectors if using hot air) and plenty of good quality flux and it's a fairly easy job. If you don't think you're able to do that safely then there are companies that you can send them off to to be repaired.
Hope that's some help.

View attachment 25471

Many thanks for the reply, very good to see there are still people following this topic.
Just to recap the symptoms:
1. Cluster works perfectly with car running, responds to brightness adjustment, no flickering, no spurious warning LEDs lit.
2. When ignition is switched off, the cluster switches off including the backlight.
3. A few seconds after locking the car, the cluster backlight comes back on and stays on draining the battery.
4. Pulling fuse 15 (5A) kills the backlight, but also kills time and mileage LCDs (which are supposed to stay on, but without backlight).

I have taken out my cluster (Seat Leon MK1 1M0920902A) and did the following:
- a thorough inspection of the back of the green and black connectors. Cluster is nice and dry.
- cleaned up all soldering joints for these connectors (minor corrosion only). Visually all pin soldering looks solid, no cracks etc. Checked continuity with multimeter between permanent battery live, switched live(s), ground, and all other pins.
- attempted a bench test (out of the car, on kitchen table) of the cluster by ONLY connecting pins 9A and 24A to ground and 23A to battery positive. All other pins not connected, incl. Green connector (with can bus) fully out.
Cluster backlight comes on immediately.

A bit stuck at this point:
- visual condition of the pin soldering, tells me green and blue connectors are fine. Also no measured shorts between permanent and switched battery live (at connectors at least).
- backlight is on when just permanent battery live + battery ground is on. This tells me that EITHER the cluster has an internal pcb short somewhere, which cause the +12V to jump to "ignition switched side" OR cluster requires a ground/voltage/signal on some other pin(s) to force the backlight to sleep.

Dear fellow members, please help!

Note (copied from another forum and verified per wiring diagram):
KLINE 25A
CANH 27B
CANL 28B
12V 1A (DIN 15, battery switched live)
12V 23A (DIN 30, battery permanent live)
12 30A (battery switched live from ignition switch)
GND 9A (DIN 31)
GND 24A (DIN 31)

A = Blue connector
B = Green connector

 

[mty12345]

Many thanks for the reply, very good to see there are still people following this topic.
Just to recap the symptoms:
1. Cluster works perfectly with car running, responds to brightness adjustment, no flickering, no spurious warning LEDs lit.
2. When ignition is switched off, the cluster switches off including the backlight.
3. A few seconds after locking the car, the cluster backlight comes back on and stays on draining the battery.
4. Pulling fuse 15 (5A) kills the backlight, but also kills time and mileage LCDs (which are supposed to stay on, but without backlight).

I have taken out my cluster (Seat Leon MK1 1M0920902A) and did the following:
- a thorough inspection of the back of the green and black connectors. Cluster is nice and dry.
- cleaned up all soldering joints for these connectors (minor corrosion only). Visually all pin soldering looks solid, no cracks etc. Checked continuity with multimeter between permanent battery live, switched live(s), ground, and all other pins.
- attempted a bench test (out of the car, on kitchen table) of the cluster by ONLY connecting pins 9A and 24A to ground and 23A to battery positive. All other pins not connected, incl. Green connector (with can bus) fully out.
Cluster backlight comes on immediately.

A bit stuck at this point:
- visual condition of the pin soldering, tells me green and blue connectors are fine. Also no measured shorts between permanent and switched battery live (at connectors at least).
- backlight is on when just permanent battery live + battery ground is on. This tells me that EITHER the cluster has an internal pcb short somewhere, which cause the +12V to jump to "ignition switched side" OR cluster requires a ground/voltage/signal on some other pin(s) to force the backlight to sleep.

Dear fellow members, please help!

Note (copied from another forum and verified per wiring diagram):
KLINE 25A
CANH 27B
CANL 28B
12V 1A (DIN 15, battery switched live)
12V 23A (DIN 30, battery permanent live)
12 30A (battery switched live from ignition switch)
GND 9A (DIN 31)
GND 24A (DIN 31)

A = Blue connector
B = Green connector

Sounds like you've covered most of the angles. Like you say I imagine it's probably an issue on the board somewhere. There is very limited information on how it functions.

 

[N4GE]

Well I've had the instrument cluster in and out of the car a few times now, getting pretty handy at it, and at stripping it down

However, not sure I'm on right track. I retouched the solder joints on the blue connector, put it back in car this afternoon, but I still have some faint warning light illumination even with power off (traction, the temperature LED, something else). Also, the immobiliser isn't actually fixed, sometimes it fails to disable, sometimes it works fine. The cluster illumination is also intermittent. Gauges do seem to turn on (they were originally intermittent too).

I took the cluster out again this afternoon, and brought it back to workbench. I desoldered all the pins for each connector, and then resoldered them cleanly as I could. I haven't reassembled/tested yet.

Is there anything else I should be soldering/testing? So far, I've only been working on the soldering of the two connectors. Also, I guess this could be down to the wiring harness or something else more difficult to trace. The connectors themselves look clean & dry, so I haven't tried cleaning those pins etc., nor have I been cleaning the fuses or their holders.

Once I hit 15 posts I'll post a couple of pictures.

Hey buddy, I hope you solved the issue in the end? I have a similar issue with my `Seat Cupra 52' 1.8T` after coming back from abroad and finding a water had got in the car from some worn door seals. The immobiliser is going off and I can't start the car... I have also put a new battery in the car recently.
I am also going down the path of removing the cluster and checking the connector points for any flakey connections.
Just to confirm, did that fix your immobiliser issue?
Thanks in advance!