HEVAC lighting help please!

Hi all, I'm totally new to this site, looks great so far, lets hope all those brains out there may help me!
My P38 Range Rover 4.6 v8 2001 has the A/C std heating control panel I think called Hevac unit with heated seat buttons. Since I've had vehicle 18 months, I haven't had any back lighting, but screen works fine also when pressing any button that lights ok. So it all works, except night time back lighting, anoying. Can't see buttons at night..

So I bought the replacement bulbs, took centre unit apart, your details on this helped, replaced bulbs but no different!! Fuse 8 ok, especially as it all works fine, strange.

I want to check feed from light switch to check live but which one is it? As screen works, button lights work then guessing earth ok, prob feed.

Sorry to go on, just anoying, any help would be appreciated, wiring loom diagram?

Thanks all
'T'

well sorry mate can't help you
but WELCOME to looneyzone anyway

You need a copy of RAVE as this has the Electronic Troubleshooting Manual (ETM) in. This contains all the wiring diagrams you could possibly need (with the exception of the SRS system).

Even the workshop manual part of RAVE would also help at this point as it lists what each pin on the unit is for, so my advice is get a copy of RAVE

In the mean time (in true Blue Peter style, heres one I prepared earlier) I just happen to have a spare HeVAC panel here, so, check that 12 volts is getting to this pin on the connector to the panel...



On the HeVAC panel side its pin 6 but obviously you will need to pull the panel, unplug it all and then figure out on the connector that goes into that plug which hole mates with pin 6, should be pretty easy. Then, hook your tester up to the correct hole and make sure the negative probe is touching a ground point, make sure key is in ignition to first stage, turn side lights on and find out what voltage you have. My guess is you will have 12 volts, especially if everything else, like the radio etc is lighting up fine at night.

If that is the case you most likely have a duff HeVAC panel.

Let us know how you get on though.

-Wills

Thanks one and all for the welcome, especially at some strange early hour.

I do like the true Blue Peter details, brill, thank you. I can as you say work with that, I shall test tomo (later today) & see. PS yes radio works fine. Strange fault maybe a dry joint on printed circuit board or broken earth solder?

This Rave manual sounds good, forgive ignorance what is it, what form does it take and where from? Thanks again, appreciate efforts all

Triathlonman said:

Thanks one and all for the welcome, especially at some strange early hour.

I do like the true Blue Peter details, brill, thank you. I can as you say work with that, I shall test tomo (later today) & see. PS yes radio works fine. Strange fault maybe a dry joint on printed circuit board or broken earth solder?

This Rave manual sounds good, forgive ignorance what is it, what form does it take and where from? Thanks again, appreciate efforts all

Click to expand...

See here...

RangeRovers.net :: View topic - RAVE Download - comes with free beer!

-Wills

Thanks 'Wills', going to start download, may go to bed then!! Cheers, I will let you know how I get on.

The Green Oval - Downloads | Land Rover Data
or this one perhaps
we are helpfull on here, SOMETIMES

i know you found one but as it took me ten mins to find it i'll post it anyway
use search at the top of the page, it,s good (when you can find wat your after that is)

Good morning, thanks again for support, the plot thickens.. I've regained access found pin 6 as described it is a switched live feed but showing 7.75volts not 12v? the earth is showing a good continuity, sound.

Wonder if I can put 12v tounit to light bulbs as test? thoughts? I am downloading Rave but takes ages, big files, maybe that'll help.
Cheers

Triathlonman said:

Good morning, thanks again for support, the plot thickens.. I've regained access found pin 6 as described it is a switched live feed but showing 7.75volts not 12v? the earth is showing a good continuity, sound.

Wonder if I can put 12v tounit to light bulbs as test? thoughts? I am downloading Rave but takes ages, big files, maybe that'll help.
Cheers

Click to expand...

hmmm, have you got the dimmer setting thingy for all the panel lights set to max??

You can, very carefully, put 12 volts onto pin 6 of the HeVAC unit and it everything is working then it will light all the lights up. However, when I tried this I was also sending 12 volts to pins 1,2 and 3, earthing the panel with pin 4 and then putting 12 volts onto pin 6. I don't know whether you will need to do the same or not. Incase you haven't got RAVE yet here are the pin outs of that connector so you know what to do. If you have a 12 volt power supply inside and can rig something up on a bench then its better to test inside so you dont mess anything up.




Keep us updated!

-Wills

Thank you for your efforts, very much appreciated.
Have done as suggested, bench tested with 12v, no lights! think unit got a fault internally.
Opened unit, traced through from a bulb to pins, not easy got so far but with resistors etc in circuit not really possible. Can't find a fault!
Think as it all works except lights, annoying as it is may have to live with it until I can find quality replacement unit for very little money, as only really buying lights!
When returned to vehicle it put up the 'book' symbol but cleared when ignition cycled on off.
I think thats prob as far as I can go without large costs, once again many thanks for your support, it's great to deal with people who care.
Cheers
Clive

Triathlonman said:

Thank you for your efforts, very much appreciated.
Have done as suggested, bench tested with 12v, no lights! think unit got a fault internally.
Opened unit, traced through from a bulb to pins, not easy got so far but with resistors etc in circuit not really possible. Can't find a fault!
Think as it all works except lights, annoying as it is may have to live with it until I can find quality replacement unit for very little money, as only really buying lights!
When returned to vehicle it put up the 'book' symbol but cleared when ignition cycled on off.
I think thats prob as far as I can go without large costs, once again many thanks for your support, it's great to deal with people who care.
Cheers
Clive

Click to expand...

It depends on how much you really want to spend, ones that end up on eBay usually have something wrong with them in someway, most likely a dead display or very segmented display. If you can live with it then thats cool but if I remember correctly a new HeVAC panel is around £174. So it depends on how much you want to spend I guess.

-Wills