BMW M44 318is factory tachometer and coolant temp.

[Onime]

Have anyone MSed M44. I have almost finished, car is running nicely. OK now I have tachometer and coolant gauges in TS, but I want to keep factory gauges alive. I cannot find out how to get them worked. Because they are directly wired into MS, the gauges on dash naturally does not get any signal. I was searching in factory diagrams and so on, but cannot find where the hell tachometer gets signal from.

Thing is that, tachometer should get signal from crankshaft sensor or some filtered/converted signal from ECU. Because crankshaft sensor was directly wired (not sure maybe signal cable is forked somewhere in between sensor and ECU, and ECU switched some ground for it on key) in factory ECU (Bosch DME 5.2) tachometer should get signal frome ECU, because in this case no other sources are left. But I cannot find any output pins on ECU connector. At least in documentation.

If anyone have done same thing, please save my time and tell me how engine coolant and tachmeter get signal on this particlular EMS.

[nuvolarossa]

You didn't read factory diagrams enough, tell me the truth

- Maybe you are making a custom wiring loom? or swapping the engine to another car?
- Are u using megasquirt as 100% standalone, removing bosch ecu or using the ms3 as piggyback? If using it as piggyback don't do that, change your mind and ditch the stock bosch. It'll be way easier with ms3 only as 100% standalone and it will do everything stock ecu does. (except immobilizer and fuel consumption gauge in cluster/obc)

Whatever, let's start:


The m44 clt sensor has 4 pins.
You must think it's like two sensors in the same housing, that's why it has 4 pins.
Pins are numbered at sensors connector (try with light and magnifier if u don't see them)

Pin 1 and 2 of the sensor go straight to the temp gauge in the cluster. If you are using these for megaquirt you're wrong, restore them as they were from factory and your gauge will work.
Pin 3 goes to ms3 CLT signal and pin 4 goes to ms3 sensors ground.
Pin3 (CLT signal)can be found at 88pin connector, pin74.


That's it. It sounds like you cut the wires meant for cluster and hooked them to ms. That's why your cluster isn't working. You should restore them and use the other two for megasquirt.

The two circuits have different transfer curve too (e.g. different resistance), so you need to measure the right values, otherwise the ms3 will read wrong.

About tachometer.
(things are two, you have the wrong wiring manual, or you got scared by the massive number of pages )

Jokes aside, you must drive the tachometer from megasquirt just as the stock ecu did. Pin 26 of ms3x is TACHO OUT.
You can connect it to pin 80 of the 88pin bmw ecu connector, or straight behind the cluster at connector x16 pin20 (there are three connectors, x16 is the 26pin WHITE one, not blue). There are other forks of that wire, but check bmw diagrams if you need more. Those two points are the start and the finish of the wire.

NOTE 1: JP3 jumper on ms3x board should NOT be jumped, or it will not work.
NOTE 2: all these wires go to the 88pin ecu connector, so it would be easier to take them from there, instead of cut&splice all the wires inside the engine compartment... if you use them from the 88 pins, remember to connect grounds too! Check bmw manual for 88pin pinout.

GL with the project, I love those cars.

[Onime]

You didn't read factory diagrams enough, tell me the truth

OK I'm lazy , do you think I will go back to docs until you are here? .

- Maybe you are making a custom wiring loom? or swapping the engine to another car?

No native E36.

- Are u using megasquirt as 100% standalone, removing bosch ecu or using the ms3 as piggyback? If using it as piggyback don't do that, change your mind and ditch the stock bosch. It'll be way easier with ms3 only as 100% standalone and it will do everything stock ecu does. (except immobilizer and fuel consumption gauge in cluster/obc)

Three things, hate imobilizer and imobilized ECUs, hate piggybacks, love MS. So 100% MS3.

That's it. It sounds like you cut the wires meant for cluster and hooked them to ms. That's why your cluster isn't working. You should restore them and use the other two for megasquirt.

No, as you also suggested, I cutted 88pin connector at ECU, and took CLT signal and ground from there, so wires to cluster are untouched.
Just to make sure, the circuit for CLT gauge in dash is activated on key and it is independant from ECU. Is this right?

About tachometer.
(things are two, you have the wrong wiring manual, or you got scared by the massive number of pages )

Jokes aside, you must drive the tachometer from megasquirt just as the stock ecu did. Pin 26 of ms3x is TACHO OUT.
You can connect it to pin 80 of the 88pin bmw ecu connector, or straight behind the cluster at connector x16 pin20 (there are three connectors, x16 is the 26pin WHITE one,

Nice, this s**t always confused me:

NOTE 2: all these wires go to the 88pin ecu connector, so it would be easier to take them from there, instead of cut&splice all the wires inside the engine compartment... if you use them from the 88 pins, remember to connect grounds too! Check bmw manual for 88pin pinout.

I think grounds can be the issue with CLT if its circuit activation is dependant on ECU.

GL with the project, I love those cars.

Tnx. They are nice, but usually they need little more power .

[nuvolarossa]

ok I'm writing you a pm. That manual is wrong.

[dcxm44]

Have anyone MSed M44. I have almost finished, car is running nicely. OK now I have tachometer and coolant gauges in TS, but I want to keep factory gauges alive. I cannot find out how to get them worked. Because they are directly wired into MS, the gauges on dash naturally does not get any signal. I was searching in factory diagrams and so on, but cannot find where the hell tachometer gets signal from.

Thing is that, tachometer should get signal from crankshaft sensor or some filtered/converted signal from ECU. Because crankshaft sensor was directly wired (not sure maybe signal cable is forked somewhere in between sensor and ECU, and ECU switched some ground for it on key) in factory ECU (Bosch DME 5.2) tachometer should get signal frome ECU, because in this case no other sources are left. But I cannot find any output pins on ECU connector. At least in documentation.

If anyone have done same thing, please save my time and tell me how engine coolant and tachmeter get signal on this particlular EMS.

Can you share a base map for M44 please? thanks