So according to my schematic,
On c0230( instruments) pin 9 the AC pressure sense sends a 0-5v signal . The instruments sends the data over canbus to the engine ECU for ideal control, cooling fan speed control and AC compressor clutch cutout.
Also on c0230 pin 20 the AC evap sense input is sent from the instruments over canbus to engine ECU.
On c0233(instruments) pin 13 AC sense input, the instruments sends that input trigger as a message over the canbus too
Although it says td4/Nas for the evap and the pressure sense, all the wires were in the connectors that came with my 1.8 instruments!
 
pscan.eu said:
The only wiring diagram that I have for a K1.8 Freelander is for a year 2002 LHD.
According to that:-

C0275-4 on the A/C switch goes to C0233-13 on the instrument panel.
I don't see anything else to do with A/C going the instrument panel. When you say "two a/c switches" what do you mean by the second one please?

I also see a two pin "evaporator sensor" connecting to C0914-37 and C0914-47 of the MEMS3.

I also see a three pin "air conditioning pressure sensor" connecting to C0913-57, C0913-71 and C0913-70 of the MEMS3.

if you have a wiring diagram that says something different please elaborate.
Click to expand...
There are wiring diagrams for all models (I'm sure) in the Rave workshop manual...

https://www.landyzone.co.uk/land-rover/rave-disk-maintenance-manual.260227/

There's 2 versions being pre and post 2000.

I don't think there is 1 for the facelift. I dunno how different the facelift is.
 
dazq said:
So according to my schematic,
On c0230( instruments) pin 9 the AC pressure sense sends a 0-5v signal . The instruments sends the data over canbus to the engine ECU for ideal control, cooling fan speed control and AC compressor clutch cutout.
Also on c0230 pin 20 the AC evap sense input is sent from the instruments over canbus to engine ECU.
On c0233(instruments) pin 13 AC sense input, the instruments sends that input trigger as a message over the canbus too
Although it says td4/Nas for the evap and the pressure sense, all the wires were in the connectors that came with my 1.8 instruments!
Click to expand...
This is very useful. thanks!
I am thinking that I might do some CANbus tapping on our TD4. I would like do this non-destructively though. Anyone know if a manual TD4 still has the cruise control plug even if cruise isn't present? that would be an easy place to tap into CANbus. Any other suggestions?
Wouldn't it be amazing if connecting the sensors to 1.8 or KV6 cluster causes it to start transmitting the sensor output over CANbus like it does on a TD4.....
 
I wondered how the 1.8 manual cluster would work.
So I plugged it into my 2001 td4 AUTO to see.
Everything works as is , gauges read totally the same, gearbox position displays, no amigos. Everything is Spot on. So I can only assume the can messages are being sent out correctly.
Unfortunately my air con needs a regass so unsure if that is ok, though it does seem to work (just not cool), I also don't have cruise control fitted.
 
Just to get this straight in my head, which aches !! Are we trying to get the 1.8 air con configured as a TD4 so that the Rover 75 BCU is not required? Am I right in thinking that the BCU generates the canbus signals that the ipack does on the TD4 ?

Also, just a thought, and this is a bit out of my area of expertise....could the Rover 75 ECU be used to run the engine and all signals necessary for cooling and Air con be fed to the original F1 ECU so that the old F1 ECU becomes a cooling ECU ??

Sort of piggy back but only where inputs are required.

Much prefer configuring hardware and wiring, tis easier :)
 
1. reverse engineer CANbus signals for A/C inputs (switch, pressure evap sensor) that come from the TD4 cluster.
2. connect the A/C pressure evap sensor to the cluster on the 1.8K, like it is on the TD4 and see if makes the same CANbus signals, or not.
3. reverse engineer the 75 CANbus signals from the 75 BCU and see how different or same they are to the Freelander ones.
4. Get the 75 MEMS3 to understand the FL1 CANbus signals from the cluster, if possible.

Edited to correct a mistake. On the TD4 the A/C pressure sensor does go to the cluster, but I think maybe the Rover 75 MEMS3 doesn't need this data from the cluster anyway because it gets it from a trinary switch connected directly to the MEMS3. The problem is the evap sensor because on a 75 MEMS3 it goes via CANbus from the BCU, where as on a Freelander MEMS3 it does straight to the ECU.

You can't get a FL1 engine ECU to control the A/C when it isn't controlling the engine; that's too hard. It would be easier to control the A/C clutch myself independently of the engine.

I did make a tiny bit of progress today. Behind the radio there is a loop of loom that goes to a multiplug on the right of the radio aperture, and, part of that loom is the CANbus pair that goes to the instruments. It's pretty obvious because it's a twisted pair. This location is really close to the diagnostic socket so I got a couple of spare pins from the diagnostic socket of a scrap Freelander and put them in the diagnostic socket empty places 6 and 14 and ran a short pair and tee'd it into the loom behind the radio.

For reference yellow/black is CANhi and yellow/brown is CANlo.

I can now just plug my CAN sniffer tool straight into the normal diagnostic socket to tap into the CANbus which I think is pretty cool.

Andy, I still need to understand how a Rover 75 trinary switch works, as in, what to feed into a Rover 75 ECU so that it thinks things are "good".
 
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Extract of manual posted above. High and low pressure in series and break if too high or too low. Medium usually open and makes if condensing required. All switch a 0 volts to ecu.
 
I don't know if this is any use or assistance, but the piccy attached is for r75 .
 

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dazq said:
I don't know if this is any use or assistance, but the piccy attached is for r75 .
Click to expand...
The evap sensor is connected to the BCU. So the BCU sends evap temp to the IPK over K line and then the IPK sends it to the MEMS3 over CANbus? wow that's nuts
 
The Freelander K1.8 evap sensor is 5.3 Kohm at 22 deg C. So I don't think it's a switch, probably a thermistor or something.
I will need to disconnect it on the TD4 and put different resistances in whilst monitoring the CANbus messages so I suppose either the cluster or the centre console will have to come out to get to a connector. oh Joy.
 
Pscan you mention tapping into the can wires at the instruments.
If you look at the schematic (Freelander) it shows the instruments can going to the abs and then another set of pins on the abs going to the engine ECU.
Do you know if the abs is relaying the can signals or are those pins connected internally?

I began doing my can taps in the ECU enclosure in the engine bay but if all the can data will be at that point under the dash then it is much neater.

According to what I discovered (from my notes) the evap sensor on the Freelander is a variable resistance to gnd as you said and not a switch.
 
Last edited:
I am seeing the same CANbus messages whether I tap at the engine ECU or at the cluster. My understanding is that the pins are simply shorted on the ABS controller.

I tapped into the CANbus behind the radio. I stripped half an inch of insulation off of each wire without cutting it, folded the exposed wire in half and crimped on a spade:-

20231008_221146.JPG


then I added to pins to the diagnostic socket (the standard positions for CANhi and CANlo are unpopulated). You have to lever open a little door on each side of the socket to insert or remove the pins:-

20231008_211844.JPG
 
pscan.eu said:
I am seeing the same CANbus messages whether I tap at the engine ECU or at the cluster. My understanding is that the pins are simply shorted on the ABS controller.

I tapped into the CANbus behind the radio. I stripped half an inch of insulation off of each wire without cutting it, folded the exposed wire in half and crimped on a spade:-

20231008_221146.JPG


then I added to pins to the diagnostic socket (the standard positions for CANhi and CANlo are unpopulated). You have to lever open a little door on each side of the socket to insert or remove the pins:-

20231008_211844.JPG
Click to expand...
That's a great idea. I might do something similar in my EV build.
 
The only downside is that if I want to connect a normal diagnostic tool like pscan and monitor the CANbus at the same time (for example to correlate live diagnostic data with CANbus packets) then I'm going to have to use Y lead to connect both tools at the same time. As the two tools are using different pins I think it will probably work.
 
pscan.eu said:
The only downside is that if I want to connect a normal diagnostic tool like pscan and monitor the CANbus at the same time (for example to correlate live diagnostic data with CANbus packets) then I'm going to have to use Y lead to connect both tools at the same time. As the two tools are using different pins I think it will probably work.
Click to expand...
Or install a second OBD2 port in parallel
 
some more progress.
I pretty much have the whole electronics for a Rover 75 on my workbench, taken from a scrap car many years ago.
I can see that 0x615:B0 0x80 appears to be A/C switch on just like the Freelander cluster.
However the payload of this packet is 8 bytes on the 75 but only 5 bytes on the Freelander, so it depends whether the ECU will reject it on wrong length or whether it will just read the first byte anyway.
I can also see that 0x618:B2 is reacting to the evap temp sensor just like the Freelander, but again it has 8 bytes instead of 5.

I think that next step is to make a fake trinary switch and see if it actually works.
 
The Freelander 1 has a "dual pressure" switch with three pins for the air-conditioning refrigerant pressure. It's connector is C1257. I need to understand what the logic of this switch is. A normal switch has two states which for a pressure sensor would be high and low. I'm guessing that just like the Rover 75 trinary switch this one has high, medium and low?

Any one got any documentation that describes it?
 
Looking at this and taking some readings:
The pressure sensor has 3 wires. 1. Purple/Black, 2. Blue / Green, 3. Orange /Blue.
The pressure sensor is an active transducer and obtains 5V from the ECU on pins 1 (0V) and 3 (+5V).
Pin 2 wrt Pin 1 (0V) gives a voltage back to the ECU dependent on pressure.

On a good working system I measured 0.86 V and on a not working system I measured 0.1 V

The 0.86V activated the A/C clutch no problem, the 0.1 V did not allow the clutch to be activated.
 
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thanks
so I need to make a circuit that feeds 5V to the sensor and when it sees over some threshold coming back it puts the trinary inputs on the R75 ECU in the "good" state and when under that in a "bad" state (probably open the hi/low switch).
 
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