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I thought I had finished my Instrument Cluster refurb, but a test installation revealed the "D" light had failed on the Transmission Range Display bar / Gear Selection Indicator / PRND321 lights (Whatever you want to call it).
It's a pretty common failure I guess - That little bulb is probably lit more than any other globe in the car.
They are still available as a new part (62111373099), but for a ridiculous price!
US$220 at https://www.schmiedmann.com/en/product/ ... -1-373-099
So I sourced a 2nd hand part from my friendly local Bavarian Classics & Restorations place and intended to swap it over.
As I was inspecting the globes, one globe broke off
and another 2 followed shortly after.So I decided to go all the way and replace the incandescent globes with LEDs. Do it once, do it right!
You can see that the middle 'D' globe here has been replaced previously.
PARTS & TOOLS
* Soldering Iron & Solder
* Solder sucker / Solder remover
* Small needle nose pliers to bend the legs
* T5 Wedge LED globe replacements (or similar)
I bought a bunch of white T5 Wedge LEDs from my local Jaycar store (Australia) which are a direct drop-in replacement for the T5 wedge globes used for dash lighting.
https://www.jaycar.com.au/t5-wedge-repl ... lobe-white
- Jaycar T5 Wedge LEDs.png (54 KiB) Viewed 1290 times
Melt, pinch and remove the white plastic shroud
Desolder the old globes. A "solder sucker" or desoldering braid works well.
DISCOVERY
Find the polarity of your LEDs.
LEDs are "Light Emitting Diodes". Diodes are polarity sensitive, meaning that power will only flow one-way through a diode.
Usually, the longer leg of a Diode is (+) and the shorter leg is (-), however the legs of my LEDs were wrapped around the plastic wedge base making it difficult to see which leg was longer (+).
Applying 12V to the legs quickly sorted out which was which.
For my LEDs, the leg connected to the internal resistor was (+)
Find the polarity of the circuit board
This took some trial-and-error.
Ultimately I discovered that GROUND (-) is always the pin closest the '1' gear light end of the board. This is the same end as the Grey/Black wire tail.
ETM page 2460-7 has a reference which sorta helps, but more on that later.
I have marked the board with + and - in white paint pen so I don't forget.
CONSTRUCTION
Resolder the new LEDs onto the board.
Ensure the polarity is correct: (-) leg towards the right of this picture.
And (-) is to the left in this picture.
BENCH TESTING
Using a 12V test power supply (a 9V battery will also work in a pinch):
Connect Ground (-) to the point shown in Blue (or the left pin of any LED).
Apply power (+) to any of the pads at the bottom.
Move your (+) terminal between the pads to test each LED.
The LEDs should each light up as you touch a different pad.
The 'Fault Light' LED operates independently from the others.
CAR TESTING
The transmission display can be tested in the car without needing to reassemble the whole instrument cluster.
Plug the circuit board into the flat wiring harness.
Key in the RUN position, without the engine started.
Handbrake on and foot on the Brake.
Move the automatic transmission selector through the range and observe each LED light up.
Pull the Headlights on and turn the dimmer down to check if your LEDs are dimmable (mine are
)WIRING PINOUTS
The circuit board's pinout information is scattered throughout ETM section 2460, so I created a simplified table.
The spacer between pins 2 and 3 aligns with the gap on the circuit board connection pads.
INSTALLATION TO CLUSTER
Reassemble the white shroud as best you can.
Insert the board back into the cluster.
The new LEDs are a little bit fatter than the original T5 incandescent globes, so the white plastic shroud sits a bit proud of the board.
Unfortunately this prevents the board from being fully inserted back into the cluster slots.
No big deal, it sits in there nice and tight and will not move.
REASSEMBLE TO CAR AND TEST
Put everything back together and pat yourself on the back for a job well done.
TROUBLESHOOTING
- If no LEDs light up on the bench test, check your polarity. You may have the LEDs installed back to front.
- If one or two LEDs don't light up, check your soldering joints or individual LEDs for failure.
- If LEDs DO light up on the bench, but not in the car, you've definitely got them installed back-to-front. Follow the bench testing instructions diagram above to confirm. You'll need to desolder, flip the polarity and resolder them again. (Don't ask me how I know this
](./images/smilies/eusa_wall.gif "Brick wall")
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