P38A Hevac wiring

Tested the blowers yesterday all good flaps all moving but problem is no lights at all on hevac just replaced all new bulbs the only thing that lights up are the direction buttons at the bottom to show where air is coming out no screen either question is what colour is the wiring for the lighting as there’s 4 plugs into the back of it cheers bloody nightmare I know

all in RAVE

Looked at that it’s all bloody Chinese to me electric diagrams just wondered I’ve anybody had same experience and new what colour so could follow that one back for a break just going to check all the hevac fuses

pete12345 said:

Tested the blowers yesterday all good flaps all moving but problem is no lights at all on hevac just replaced all new bulbs the only thing that lights up are the direction buttons at the bottom to show where air is coming out no screen either question is what colour is the wiring for the lighting as there’s 4 plugs into the back of it cheers bloody nightmare I know

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I seem to recall bulbs for the screen and others for the screen but it was a long time ago and I might be mistaken. I also recall a ribbon connector on the screen. Martyuk does a refurb kit.

I’ve replaced all them grrrr it’s not a ribbon now more like a sponge thing checked the fuses so just figured it’s a dodgey wire is the ecu for the hevac under the passenger seat

Screen can be checked by shining a torch through the hole where the bulb goes. My HEVAC lighting didn't work when I had the instrument cluster out during dash removal & Audi core install. Had to plug it in for lights to work. Did you do all 4 bulbs ? The green one is for the LCD.



Pin-6 for illumination:



Connector positions:

Yer did all the bulbs will study that diagram tomorrow but cheers pwood

Check pin 6 has volts & then work backwards

Checked the white plug on hevac pin 6 is showing 0.58 and on pin 1 ignition it’s showing 11 on the multimeter any clues now as to next step as me and electrics just don’t understand each other thanks in advance

Check pin-2 on BECM connector C258. It should have power when ignition is on. If there's voltage at the BECM, but not at HEVAC, then there's a break in the splice or the wires. I believe the LCD bulb should should always light up, but the others are probably only on when lights are on.

Also check the wire from "HEVAC C246B pin-11" to "Instrument Cluster C242 pin-20". This one controls LCD brightness, and dims both HEVAC & Cluster LCD when lights are on. See bottom left on diagram I sent earlier.

And don't forget to try adjusting the dimmer control on the indicator stalk. Set it to maximum.

Do you have a Nanocom ?? In the HEVAC Outputs screen, there's an "LCD Test" option which forces the display lamp on.

Pwood your a hero will get to the becm and check that out cheers and also the nanocom

If you haven't already got them, go onto Nanocom forums, and download the BECM & HEVAC guides. They are at the top of the respective forum section, and there's one for each Nanocom menu . . . . .. .for example:

Cheers pwood I got the latest software tried testing the lights on hevac all the orange button lights came on but no joy with the screen lcd will test becm tomorrow and report back