E30 -90 problems with the instrument housing

[E30REDD]

I gave it a shot but it's impossible to even reach the temp sensor. I guess I would be able to touch it with a screwdriver but I still need two fingers in order to remove the clip (just to clarify, I'm talking about the blue sensor (it should be brown?) which is furthest away: https://www.dropbox.com/s/07k4g3s93uxgr ... 201002.jpg

I also found an interesting cable (Red/White and Brown) that were hanging all alone next to the air filter: http://i45.tinypic.com/6p3p55.jpg

Then, on the passenger side, I found three loose connectors with cables colored as following:

http://i48.tinypic.com/300faf4.jpg

1. Brown/Black and Purple/Black
2. Brown/Black and Purple/Black (Not 100 % sure)
3. Brown/White and Purple/Black

[BenHar]

You seem to have given one of those links wrongly.

The second two are the same picture.

And I think both are the connector for a lambda sensor if a catalytic convertor is fitted. Someone will be along to confirm.

Ben

[E30REDD]

You seem to have given one of those links wrongly.

The second two are the same picture.

And I think both are the connector for a lambda sensor if a catalytic convertor is fitted. Someone will be along to confirm.

Ben

Thank you, I have now changed the link.

According to the Wiring Diagrams, the Red/White and Brown cable (next to the air filter) is going to "Evap purge valve". Is this some kind of valve controller? I believe M42's using some kind of oil system to adjust the valves.

[Brianmoooore]

1. Brown/Black and Purple/Black
2. Brown/Black and Purple/Black (Not 100 % sure)
3. Brown/White and Purple/Black

These is all washer wiring - the screenwash pump with no connection to it is a big clue!
Plug by the air meter is for a fuel tank vent solenoid valve, which you probably don't have. Second thread this week on this one!

[Brianmoooore]

The very first test to do when faced with a non working temperature gauge is to take the C101 connector apart and use a piece of wire to short pin 4 of the body side half to ground (rear left bonnet catch) with a piece of wire. Turn the ignition on, and the temp. gauge should go to full hot.

[E30REDD]

The very first test to do when faced with a non working temperature gauge is to take the C101 connector apart and use a piece of wire to short pin 4 of the body side half to ground (rear left bonnet catch) with a piece of wire. Turn the ignition on, and the temp. gauge should go to full hot.

That's exactly what I was going to ask you!

Well, I can't find the Brown/Purple cable that's comming from the temp sensor under the intake. It's cut off about 10 cm from the C101, but I can't find it in the Loom.

[E30REDD]

The very first test to do when faced with a non working temperature gauge is to take the C101 connector apart and use a piece of wire to short pin 4 of the body side half to ground (rear left bonnet catch) with a piece of wire. Turn the ignition on, and the temp. gauge should go to full hot.

That's exactly what I was going to ask you!

Well, I can't find the Brown/Purple cable that's comming from the temp sensor under the intake. It's cut off about 10 cm from the C101, but I can't find it in the Loom.

Good news, the temp gauge went full hot when I connected it to ground.

Now I just have to connect the temp sensor cable to the C101 but the problem is that I can't find the Brown/Purple cable from the Loom. Should it be comming from here?: http://i47.tinypic.com/2h4ls0y.jpg

[Brianmoooore]

Yes, it's one of the wires coming up through that trunking.

[E30REDD]

Yes, it's one of the wires coming up through that trunking.

There is no Brown/Purple cable coming up through that trunking. I think that the Brown/Purple cable is going from the temp sensor to a box which is right under the intake.

It's impossible to reach it and I can't see anything, all my thoughts are based on feelings from my hands.

[Grrrmachine]

There's nothing else we can do for you until you get that intake off. The wire is either there, or it isn't. If it isn't, you need to put one there.

It might make more sense for you just to buy a proper M42 loom and fit it straight to the C101.

[E30REDD]

There's nothing else we can do for you until you get that intake off. The wire is either there, or it isn't. If it isn't, you need to put one there.

It might make more sense for you just to buy a proper M42 loom and fit it straight to the C101.

Is there a box under the intake? It feels like there's a box that has a few cables connected to it where one of the cable is the Brown/Purple that's coming from the temp sensor.

What is this box called and what does it do?

[E30REDD]

There's nothing else we can do for you until you get that intake off. The wire is either there, or it isn't. If it isn't, you need to put one there.

It might make more sense for you just to buy a proper M42 loom and fit it straight to the C101.

If I would buy a new loom I would still have to remove the intake.

What is the box under the intake for?

On the C101, is Pin 8 (White/Black) the economy meter that shows how much fuel I'm using?

On the C101 Wiki-page there are two cables that are White/Black, pin 8 and 16. Why is that?

I'm also wondering what the following means:

Engine speed input
Speed signal out
Switched power

[Grrrmachine]

The only box around the intake should be the Throttle Position Sensor under the throttle body, although I'm not an M42 expert.

Yes, pin 8 is the econometer cable

I don't know why BMW made two cables white/black.

Engine Speed Input comes from the ECU, and drives the Service Interval indicator
Speed signal out is for the tachometer
Switched power connected a circuit from your ignition switch to the engine's coil (in your case, the pack of coils). Without that, the sparks cannot spark.

[E30REDD]

The only box around the intake should be the Throttle Position Sensor under the throttle body, although I'm not an M42 expert.

Yes, pin 8 is the econometer cable

I don't know why BMW made two cables white/black.

Engine Speed Input comes from the ECU, and drives the Service Interval indicator
Speed signal out is for the tachometer
Switched power connected a circuit from your ignition switch to the engine's coil (in your case, the pack of coils). Without that, the sparks cannot spark.

Thank you, but there is a box below the intake manifold. There are a few cables connected to this box where two of them (Temp sensor for the instrument gauge and temp sensor for ECU) are connected.

This thing goes in to the box I'm talking about: http://tinypic.com/view.php?pic=2h4ls0y&s=6

[Grrrmachine]

Ahhh

This "box" is just a sleeve or channel to protect the wires from engine heat, dirt and other stuff. It's bolted to the engine block and directs all the wiring from the bulkhead to the alternator.

[E30REDD]

Ahhh

This "box" is just a sleeve or channel to protect the wires from engine heat, dirt and other stuff. It's bolted to the engine block and directs all the wiring from the bulkhead to the alternator.

Okay.

I'm not sure but I think that the temp gauge cable is going into this box. And the cable (Brown/Purple) is probably cut off somewhere in this box.

The problem is that I can't get into this box because it's so damn tight because the intake is in the way, and I would really not want to remove the intake.

[Grrrmachine]

I don't think you can access this box without removing almost everything on that side of the engine. Even teh coolant hoses and fuel pipes run above it, so it's really well hidden.

I remember earlier that you were checking the resistance of the brown/purple to try and find the temp sender wire. Maybe check the resistance of Brown/White if that wire is not connected. That wire shows up as a temp sender wire on one of my other diagrams.

Basically, with the car cold, check the resistance of ALL unconnected wires and write them down. Then drive the car to hot, and check the resistances again. The temp wire will be the one whose resistance changes from about 3000 Ohms down to around 300, cold to hot.

[Brianmoooore]

Maybe check the resistance of Brown/White if that wire is not connected. That wire shows up as a temp sender wire on one of my other diagrams.

This wire is the 'left over' from when E30s had two pin temperature sensors for the gauge. It's the one that used to connect to pin 20, and is the reason that some cars have a brown earth wire connected to pin 20 on the body side, causing fun after engine swaps.

[E30REDD]

There are only 5 wires comming from the Loom that are cut off right before the C101:

Green/Yellow - Static oil level
Red/Yellow - ABS
Brown/White - Temp gauge
White/Blue
White


I measured the resistance of all of the wires, not a single wire gave any result. I measured between the cut off wire and ground.