M44 Engine Temp Sensor Colors

[Cristian G in Oz]

Guys,

In my quest to rebuild my engine following a cracked head, I purchased an M44 head to go on my M42 block.

I have all the bits required to change it over including the dual temp sensor that goes in the head.

I have looked in the E36 Bentley and it lists the Engine Coolant Tempurature Sensor colors as:
pin 1. - Brown/Yellow
pin 2. - Brown/Violet
pin 3. - Brown/Red
pin 4. - Brown/Black

It also shows pin 1 going to the dash as -ve and pin 2 going to the dash as +ve.
Then it shows pin 3 going to the ECU Temp input and pin 4 going to a a splice, which I'm guessing is a common ground.

Now the question....
The temp sensor I have has the following:

Pin 1 - Red/White
Pin 2 - Brown (no stripe)
Pin 3 - Black (no stripe)
Pin 4 - Yellow (no stripe)

Do I just match the Pin numbers to the outputs and disregard the colors?:confused:

On the M42 there are 2 sensors on the head. 1 with a single pin (and I'm guessing a case ground) and a second sensor (the forward one) with 2 pins.
Is the single pin sensor the one for dash? and the 2 pin sensor the one for the ECU?

I can't find the M42 with 2 sensors fitted to an E30 circuit, in the E30 or E36 Bentley.

What I plan on doing is fitting connectors to the 4 pin M44 plug so that I can "plug and play" with the M42 ECU loom without cutting and soldering it.  

Hoping someone has the answer.

Cristian

[ak96ss]

FWIW, take a look at these:



The single pin one, case grounded, is the sending unit for the gauge, and the dual pin one is for the ECU.







Not sure what you are going to do with the 4th wire - the E30 instrument cluster only uses the positive signal from the sender, looks like pin 2 on the M44 unit. The other two should be (in theory) pin 3 to ECU via the BR/RD E30 wire and pin 4 to that splice, the BR/BK wire in the E30 harness. Maybe ground it?

[Cristian G in Oz]

John,

That's great info.
I was going to place the 2 "grounds" together in one connector but looking at those diagrams, I read it as the M42 2 pin plug has a "closed circuit" that would be grounded through the ECU.

The 4th pin on the M44 switch I guess I will have to extend the wire and route it to earth on the engine somewhere nearby. At least there is no shortage of studs and nuts to put it under.

And it sounds like you agree with my decision to ignore the wire colors on teh plug and use the pin numbers to wire it up?

Thanks for your help I knew someone would have the diagrams here.

It will be a couple of days but I will let you know how it goes.

Cristian (looking better for a new head now) in Oz

[ak96ss]

John,

That's great info.
I was going to place the 2 "grounds" together in one connector but looking at those diagrams, I read it as the M42 2 pin plug has a "closed circuit" that would be grounded through the ECU.

The 4th pin on the M44 switch I guess I will have to extend the wire and route it to earth on the engine somewhere nearby. At least there is no shortage of studs and nuts to put it under.

And it sounds like you agree with my decision to ignore the wire colors on teh plug and use the pin numbers to wire it up?

Thanks for your help I knew someone would have the diagrams here.

It will be a couple of days but I will let you know how it goes.

Cristian (looking better for a new head now) in Oz

Yep, looks like it does ground through the ECU, and yes, I would ignore colors and use the pin numbers. YMMV, I've never tried this...

[Cristian G in Oz]

FWIW, take a look at these:

The single pin one, case grounded, is the sending unit for the gauge, and the dual pin one is for the ECU.

Not sure what you are going to do with the 4th wire - the E30 instrument cluster only uses the positive signal from the sender, looks like pin 2 on the M44 unit. The other two should be (in theory) pin 3 to ECU via the BR/RD E30 wire and pin 4 to that splice, the BR/BK wire in the E30 harness. Maybe ground it?

John,

I have been looking at the E36 manual and it appears that the "ground" for the sensors is back through the ECU.
Do you think it would be a problem to add an extra "ground" in that group of wires?

I have ordered 2 male connectors to match the connectors for the M42 sensors and will fit them to the M44 sensor.  The extra "ground" I will either include in the sensor ECU return or put an eyelet on it and fit it to the inlet manifold mounting stud.

Looks like it will all come together.:rolleyes:

Tomorrow night (our time) I get to start putting it all back together.

Have a good one.

Cristian

[ak96ss]

Yep, saw that too, but it's just a sensor and since the E30 ECU doesn't 'care' about the ground for it, I would imagine that you would just be able to ground it to the engine. I may be wrong, but I would equate it to the way the E30 sensor grounds through the case. You should just be able to ground it to the engine and be done.

I should think that grounding it back through the ECU where there was no original provision for this may potentially cause some other issues. If it were me, I'd ground it to the block and see what happens.  

[Cristian G in Oz]

Yep, saw that too, but it's just a sensor and since the E30 ECU doesn't 'care' about the ground for it, I would imagine that you would just be able to ground it to the engine. I may be wrong, but I would equate it to the way the E30 sensor grounds through the case. You should just be able to ground it to the engine and be done.

I should think that grounding it back through the ECU where there was no original provision for this may potentially cause some other issues. If it were me, I'd ground it to the block and see what happens.  

Now that you mention it it would be smarter to ground it on it's own. The last thing I need now is the ECU going KAPUT.....

Also my plan was to make it "plug and play" to keep it as close to the original config as possible, so grounding to the case is what it should be.

Thanks for the words of sanity and reminding me of "KISS".

Cristian