Air Conditioning not working - fault codes inside

[z4_spiral]

Ok, tested the wiring loom this morning from the back of the control module. Continuity was good. Then rigged up a 5V supply (don't ask how) over the loom to check the sensor values - returning 0.7V, which is in spec (though don't know what that translates to) and more than the 0/0.1 that the module knows about.

So I think the module is toast and there's an issue with the 5V supply, but I could confirm that by sending a signal back along the sensor when it's plugged in. 1.2V from an AA should do it... If the car sees that, then I'm almost certain it's the module. Though to be fair I've never diagnosed anything that's not a guitar pedal before, and these are way more complicated so I hope I'm wrong. Probably take it to a dealer to confirm, shouldn't take long to confirm the module according to ISTA.

[enuff_zed]

Ahem................
viewtopic.php?t=138297
Just saying.

[z4_spiral]

Of course, I refitted the thing this morning after checking didn’t I? Will pull it later and check part numbers, then probably take it

[enuff_zed]

Of course, I refitted the thing this morning after checking didn’t I? Will pull it later and check part numbers, then probably take it

No worries, just me being cheeky and opportunistic.

I also have a pressure switch which I'd chuck in with it if that helps?

[z4_spiral]

I appreciate the cheek here honestly, £20 for a confirmed working unit and a pressure sensor? Unreal. Well, that's a LOT faster to pull out when you've already left the vents out and actually know what you're doing! I've attached an image below, should be compatible... right?

I've heard rumors that older IHKA's don't need programmed. I'm not sure if I believe that (because bmw things), any insight on that? If you've done coding before, any chance you could code the vin in before sending it, assuming it's compatible ok, or is that something that needs to be in the car?

IMG_6181.jpeg (52.31 KiB) Viewed 286 times

[z4_spiral]

I should really learn about coding though, because I've an airbag "detonation circuit 6, coding, at variance" issue in the left side satellite module that I'm going to need sorted, though I was honestly thinking of just dropping it off to the dealer for that one. If I can get these 2 issues sorted ok, then it's going to be a suspension refresh for me, and some happy days motoring ahead!

[enuff_zed]

I appreciate the cheek here honestly, £20 for a confirmed working unit and a pressure sensor? Unreal. Well, that's a LOT faster to pull out when you've already left the vents out and actually know what you're doing! I've attached an image below, should be compatible... right?

I've heard rumors that older IHKA's don't need programmed. I'm not sure if I believe that (because bmw things), any insight on that? If you've done coding before, any chance you could code the vin in before sending it, assuming it's compatible ok, or is that something that needs to be in the car?

IMG_6181.jpeg

Afraid I have no idea on the coding but I can say I plugged this into a facelift car for some fault diagnosis and it worked fine, so I think you should be ok?
I'll PM you my details.

EDIT. RealOem clearly states that my one supersedes yours and is exchangeable retrospectively.

[z4_spiral]

[/quote]
I plugged this into a facelift car for some fault diagnosis and it worked fine
[/quote]

Birds of a feather, the module has obtained 'invalid debugging tool' status If it worked when you plugged it in to something else, fingers crossed it will for me too.

[z4_spiral]

Ok, update time.

Parts (climate module and pressure sensor) arrived from @enuff_zed this morning, cheers mate! So of course I tried it as soon as I could, delaying lunch by an hour and angering the wife. Oops. I disconnected the AUC sensor (just in case it's at fault), and plugged in the new module.

Nope.

I then left the original sensor in the system hooked up the one he included just sitting in the engine bay and still also read 0V - I'd assume something even at atmosphere. Hooking it up out of the car to a source does show some voltage, so I think both switches are fine. At this point, I'm really frigged as to what the issue could be . It's highly doubtful that TWO modules and TWO sensors are not working ok, so really, I have to suspect the wiring or other electrical gremlins _somewhere_.

Aside from that, some more interesting notes.
- Both fuses (F22 and F39) for the climate module are ok.
- The new climate module seemed to light up and work/control just fine but it does throw an additional code for the aux. water pump, which my m54 engine doesn't have - so the module will work, but there will be errors without coding the feature out. No biggie.
- I used ISTA to engage the compressor manually (you can do this for 8 seconds at a time). This _actually works_, I see the clutch engage and I can feel the cold kick in, so there is pressure in the system for sure and the compressor isn't dead! Component eliminated for now.

So, what next? Honestly, I'm not 100% sure. To 100% rule the module out, I would need to de-pin the 3 wires for the pressure sensor AND the 2 sense wires for the AUC sensor, which I don't have the tools or know how to do (yet...) but that should allow me to read 5V from source/return on the module. Given I've had 2 modules now behave exactly the same, I doubt it's this.

To 100% rule the sensor out, I'd need a more reliable hookup of 5V to it, my *cough cough* dodgy battery packs joined together are a bit of a hack. Always wanted a nice bench power supply anyway so I might just buy one! The AUC sensor I don't care about right now, so will probably leave it disconnected for the foreseeable.

I saved the best til last. I have a new code:

Code: Select all

LSZ2: Headl.v.a.c, front load sens, sh.circ.to earth

. Now *this* is interesting. I'm off to do more research into these circuits. I wonder if they share a ground and something's amiss with it...

[enuff_zed]

- The new climate module seemed to light up and work/control just fine but it does throw an additional code for the aux. water pump, which my m54 engine doesn't have - so the module will work, but there will be errors without coding the feature out. No biggie.

Ah! I never even considered that! It's from a 2.0 which does have the auxiliary pump. Never occurred to me that they would be coded for that. Sorry.
Also sorry none of it seemed to work.

I am impressed it arrived so quickly though!

Look if it turns out not to be the correct one, or is no use to you, PM me if you want to consider a refund.

[z4_spiral]

Pondering this some more, sorry I have to think out loud and I'll be killed if I do it in the house.

The closest thing I could find to my issue online is this thread: https://www.e46fanatics.com/threads/ac- ... t-18734717

Which has made me think - I have done my previous continuity testing of only the pressure switch. This thread implies there may be a common supply between the two (yes I know it's an E46, and might be different). I'm wondering if I should be out and testing any interplay between these two. Going by the reference diagram I have, the ground for the pressure sensor is a switched ground, and the one for the auc (both heater and sense) is a chassis ground.

That I have removed the AUC sensor when testing would suggest that it's not the same fix as in that thread, but it would make me thing that maybe, just maybe, it's interfearing with the 5V supply somewhere in the loom. Easy enough to test, I'm sure even if the probes don't fit in the plug I can get a small wire in there to check continuity! Given the time of day, that's going to be a tomorrow afternoon task, get me some daylight. At this point, I'm tempted to cut the AUC wires completely, or at least de-pin them if I can figure out how. Let's see what turns up first.

I might even do this with the ignition on and the IHKA connected as well, see if anything changes... lots more things to be testing!

enuff_zed, don't worry about it, I could have checked too. Cheap diagnostics and I'm sure there will be someone somwhere who wants it in the future!

[z4_spiral]

Anyone know of any resources that would highlight the exact path connections are supposed to be routed in the car? Be handy to be absolutely sure where all the wires are supposed to go (especially ground ones, as the AUC uses brown I'd want to know if they're meant to be continuous or at a ground comb)

[z4_spiral]

Alright, froze my ass offf doing some more checking. Went at it just to poke about, with no real test plan, nothing conclusive to draw from it.

Took the connector off IHKA and had a poke, with the sensors still plugged in. Surprising reading that pin 17 (Psense) and 20 (AUC 5V supply) seem to be shorted (7ohm). This would be strange, and would make me think it should be reading 5V there, which is not what's happening.

Ok, out in the cold, with the car ignition on, and switches unplugged (P == pressure switch)

• P ground (pin 18) is chassis ground - expected given it matches to pin 4 (main return on the IHKA)
• AUC heater supply -> heater ground is 5V, which the datasheet for the TGS822 https://datasheetspdf.com/pdf/789388/Figaro/TGS822/1 suggests is correct! So, heater supply is not compromised, and heater ground is reliable.
• P+ and AUC+ have 5ohm between them - expected given what the IHKA showed about the two supplies being on the same circuit.
• AUC+ and AUC heater ground show 115ohms. I would have expected no connection. (fyi, the auc sensor itself has 1kO-10kO resistance according to the datasheet)
• AUC+ is 140ohm to ground, suggesting a fault to me.

What am I going to do with all this? Probably think it through and go and retest with care and note proper results, but it does indicate a short to me somewhere, though this same man thought the module was broke so bugger if I know. Should save myself the hassle and either bring it to someone who has a power probe, or buy one myself and just look for a short somewhere. It's got an appointment later in the week anyway to see how bad the suspension is, wonder if they have a probe...