E30 S54 Swap AC signal input to DME

[b-rad]

Yes - only issue I had was one of the hose crimps let loose with a bang. The hydraulic shop seemed a bit confused and I'll probably buy the Mastercool crimper and re-do my hoses.

I'm planning on producing more of the CAN interface boards and selling them. I could support M/S52 compressor with pressure switch or S54 compressor with pressure sensor.

I have an S50 Swap, E30 325is.
At idol, the car wants to die, is what your doing here why mine is like this.
The computer does not know that there is an AC in the car?

[gpeterson]

I have an S50 Swap, E30 325is.
At idol, the car wants to die, is what your doing here why mine is like this.
The computer does not know that there is an AC in the car?

M50/52 & S50/52 doesn't need a CAN interface. I haven't done this as I don't have an E30, but you should be able to wire it so that the DME activates an E36 A/C compressor relay, the E30 snowflake output connects to the DME snowflake input, and the E30 pressure switch signal is inverted (via relay or transistor circuit) and connected to the DME pressure switch input. It needs to be inverted because the E30 A/C controls send 12v when the compressor should be on and the E36 A/C controls pull to ground instead.

[nando]

yeah the older computers just take a single pin at the DME that tells it if the compressor is on or not. All you need to do is wire it up.

Inverting the signal should be easy. I recently found out about hex inverters when I bought my wife a new treadmill and it fried, $2300 treadmill out of warranty.. they wanted to sell me a nice $700 control board. Replaced a 64 cent part instead - it takes whatever the input signal is and makes it the opposite (high input = low output, low input = high output). There's a million ways you could do that though, relays, transitors, etc. Much simpler than a CAN interface, although CAN is a lot more sexy..

[gpeterson]

yeah the older computers just take a single pin at the DME that tells it if the compressor is on or not. All you need to do is wire it up.

Inverting the signal should be easy. I recently found out about hex inverters when I bought my wife a new treadmill and it fried, $2300 treadmill out of warranty.. they wanted to sell me a nice $700 control board. Replaced a 64 cent part instead - it takes whatever the input signal is and makes it the opposite (high input = low output, low input = high output). There's a million ways you could do that though, relays, transitors, etc. Much simpler than a CAN interface, although CAN is a lot more sexy..

To clarify - it isn't just a single pin. The M50/52 & S50/52 DMEs need the snowflake input and evap/pressure switch input to enable compressor output. MSS54 is essentially the same two binary signals + a pressure value (load) transmitted over the CAN bus.

[nando]

yeah, sorry to oversimplify.

[Bimmerman325i]

Yup, can confirm. I wired my AC switch and pressure switch into the Z3 cluster (aka CAN interpreter) and the DME (connected via CAN) kicks the compressor on/off as expected.

Super simple so long as you have some way to translate analog into CAN, such as a late Z3 cluster or Gpeterson's box.

[terraphantm]

To clarify - it isn't just a single pin. The M50/52 & S50/52 DMEs need the snowflake input and evap/pressure switch input to enable compressor output. MSS54 is essentially the same two binary signals + a pressure value (load) transmitted over the CAN bus.

For what it's worth, in Z3M mode, the DME calculates compressor torque consumption rather than relying on getting it over the CAN-bus.

[BM3Weeler]

Hello guys!
Came upon this thread looking for info about getting my cruise control functional after my m54b30 swap.
But I also stumbled upon the problem with ac....
So, I'm also interested in buying a unit.
But while I'm at it, anyone managed to get cruise control working without dsc/asc unit connected?
I have an e36 z3 setup in which I use a gaspedal potentiometer, cruise control interface and an e36 cruise control stalk.
All is working well according to INPA, but no cc...

And mister Peterson, are you willing to ship to the Netherlands?

[gpeterson]

Hello guys!
Came upon this thread looking for info about getting my cruise control functional after my m54b30 swap.
But I also stumbled upon the problem with ac....
So, I'm also interested in buying a unit.
But while I'm at it, anyone managed to get cruise control working without dsc/asc unit connected?
I have an e36 z3 setup in which I use a gaspedal potentiometer, cruise control interface and an e36 cruise control stalk.
All is working well according to INPA, but no cc...

Getting any codes? Is your DME's speed input wired & flashed to use an external source? Does an OBD2 reader show accurate speed while driving?

And mister Peterson, are you willing to ship to the Netherlands?

I'll ship anywhere if the buyer covers the additional shipping cost.

[BM3Weeler]

Morning guys, morning Peterson.
Yes, I'm getting a code, code 0
F_UW1_NR or F_UW1_TEXT don't exist in result record 1 !
F_UW2_NR or F_UW2_TEXT don't exist in result record 1 !
F_UW3_NR or F_UW3_TEXT don't exist in result record 1 !
F_UW4_NR or F_UW4_TEXT don't exist in result record 1 !
F_UW5_NR or F_UW5_TEXT don't exist in result record 1 !

Can't find anything about that on the www.
But if I understand correctly Daniel (ms43 wiki) says it has nothing to do with my cc not working.
I got a rear right wheel speed signal directly from the abs unit (e36 abs unit, teves 20) and signal is perfect.
I use pin 22 from x6004 connector.
INPA shows true speed.
In "digital values" all FGR switches work (cruise control), it's just not doing anything.
My guess is that without CAN connection to asc or dsc you can't set speed.
As with e90 and up its normal not to have cc when when you disengage dsc...

As for shipping to the Netherlands.
Of course I'm willing to cover additional costs

[BM3Weeler]

Yesssss!
With Some help I found out I need a speed signal from abs unit to dme via can bus.
Now the mk20 abs doesn't have can bus, but the mk20 asc does!
But I don't have this, so need another solution...
Is it possible to convert the right-rear-wheel sensor signal to a can bus signal with your module?
Otherwise I'm gonna get me an asc unit, ad another brake line, and connect this unit to my dme.

[R3Z3N]

Which of the pinouts plugs into the AC Compressor's one wire?
See attached image. Yellow I know I need, Green is done, Red I do not use. Also can you provide an example for the AC Relay and Fan relay needed for E30? Thanks!

[gpeterson]

Here is a modified version of the E36 ETM that shows how to connect a relay to the MSS54 DME. You can use a standard Bosch relay or E36 A/C compressor relay wired like this:

[R3Z3N]

So, my car no longer has a C136, however I found the wire was direct to my S52 ECU, which the C136 is now gone for the S54 ECU. Connect: Red/Black pin 1 from my missing C136 to pin 4 of the CAN Converter box? Pin 2 was into the S52 ECU, but now no longer if I am correct.

Now, here I am confused from this image. Does that same red/black Pin 1 C136 connect straight to compressor clutch, along with the relay from the post above? Or Just Red/Black Pin 1 C136 to Pin 4 of your adapter, and the relay is a separate circuit?

[BM3Weeler]

Just use the relay again, or buy a new relay holder so you can tuck it away in your relay box.
It needs 2 times 12 volt, is activated by a ground signal from your s54 dme, then the other wire goes to your compressor.
Did you remove all wiring too?

Connecting it directly to your s54 dme won't do any harm, but it also won't work.