E30 what is speed signal out?

Post Thu Apr 11, 2013 6:11 pm

I'm wondering what number 14 on the C101 (speed signal out to ECU) is for.

On my E30, this cable is cut off.

Post Thu Apr 11, 2013 7:45 pm

Road speed signal from the instrument cluster to the engine ECU. Tells the ECU the difference between a car that is idling while not moving, and one that is on over run with the throttle closed.

Post Thu Apr 11, 2013 7:52 pm

Okay... How does this affect my car when the wire is cut off?

My car is originally a 316 but the engine has been swapped to a M42.

Post Fri Apr 12, 2013 7:13 am

Okay, do you know what the white wire comming from the Loom is for?

Post Fri Apr 12, 2013 1:08 pm

willnz wrote:Where exactly from the loom? And is it only white or does it have a coloured stripe on it? Pic will help.

The white wire from the loom is cut off right before the C101. It's only white.

I'm also really confused about the following wires:

The left side of the picture is the loom.

http://oi48.tinypic.com/2199l3o.jpg

Post Sat Apr 13, 2013 7:38 am

willnz wrote:I have no idea what the white wire is for. Certainly in the e30, it was only used to the electric antenna and in the central locking.

Possibly the motor is from an e36 and the engine loom has a white wire in it. Is the wire coming from the engine loom?

In your pic C101 pin#8 is the signal wire to the instrument cluster for the econo meter, pin#16 goes to the diagnostic plug.

The white wire is coming from the engine loom, yes.

I'm confused because from the C101, pin 8 is White/Black, then it changes color to Black/White. And the economy meter doesn't work.

Post Tue Apr 16, 2013 5:01 pm

Post Wed Apr 24, 2013 6:46 pm

Post Wed Apr 24, 2013 7:22 pm

E30REDD wrote:My car is originally a 316 but the engine has been swapped to a M42.

But not with a genuine E30 loom, IIRC?
Any chance your 'white' wire could be grey?

Use a meter to check continuity of wires from the C101 plug to the ECU plug. Be careful not to damage the buckets in the ECU plug by forcing a meter lead probe into them.

Pin 8 should go to pin 17 (possibly a white wire)
Pin 9 should go to pin 74
Pin 14 should go to pin 73
Pin 12 (if there) should go to pin 8

Post Thu Apr 25, 2013 6:16 pm

I have no idea what car the loom is from. If there is any way to tell, please let me know.

The white wire from the loom is 100% white.

I have removed the ECU plug from the ECU (which btw was sitting loose above the glove compartment) but how do I see the pin number on the ECU side?

Ah, I have to use this one, right:

Post Thu Apr 25, 2013 6:53 pm

Okay, I miss a lot of pins in my pin slots. For example:

Pin 8 -----> 16 (17 had no pin so I tried the pin next to it, which was 16)
Pin 9 -----> Nowhere because 74 has no pin
Pin 14 ---> Nowhere because 73 has no pin

I took a picture of the ECU connector, and as you can see there are a lot of pins that are missing:

Post Thu Apr 25, 2013 7:02 pm

All the relevant pins look like they are there to me!
I think you may be viewing the plug incorrectly. Pin 1 is in the lower left in your pic.

Post Thu Apr 25, 2013 7:44 pm

Brianmoooore wrote:All the relevant pins look like they are there to me!
I think you may be viewing the plug incorrectly. Pin 1 is in the lower left in your pic.

My stupid brain is stupid, somehow I flipped it in some way. Now I got it right.

Okay, nothing makes sense to me because everything seems to be wrong except one of the pins.

9 -----> 74
14 ----> 71 (pin 71 also goes to a lot of pins on the C101) Ground?
12 ----> Couldn't find a single pin it was connected to (didn't try them all). Certainly it was not connected to pin 8.

Post Thu Apr 25, 2013 7:56 pm

If you want, you can have a look here:

http://www.e30zone.net/e30zonewiki/inde ... tronic_1.7

Post Thu Apr 25, 2013 8:00 pm

Grrrmachine wrote:If you want, you can have a look here:

http://www.e30zone.net/e30zonewiki/inde ... tronic_1.7

That's what I'm doing.

So I really have to check where every damn pin goes?

I have some wires cut off from the C101 and I'm curious what they're for. But the major problem is that the econometer doesn't work.

And another fucking shit problem is that C101 8 is first White/Black, then someone have changed it to Black/White. It's the wrong fucking cable, hence why I get no contact between pin 8 and 17.

Post Thu Apr 25, 2013 8:06 pm

So where does 8 really connect to. 73?
See if you can trace the white wire to any of the ECU pins.
Don't worry about pin 12. It's not relevant to any of your problems.

Post Thu Apr 25, 2013 8:14 pm

Brianmoooore wrote:So where does 8 really connect to. 73?
See if you can trace the white wire to any of the ECU pins.
Don't worry about pin 12. It's not relevant to any of your problems.

Well, I have trouble with my TPS: http://www.e30zone.net/modules.php?name ... highlight=

Anyway, I'm so extreeeeeemely confused, I'm about to forget what my name is. This is because some idiot have been mixed Black/White with White/Black cables. I have a thread somewhere here on E30Zone where I explained the damn problem with the changing wire colors, but I can't find the thread because my brain is about to explode.

I will be back soon with updated pin numbers...

Post Thu Apr 25, 2013 8:21 pm

E30REDD wrote: This is because some idiot have been mixed Black/White with White/Black cables.

This is beginning to look like what the problem is. We're nearly there now - once you've determined where 8, 9 and 14 of the C101 actually connect to at the ECU plug, and whether 17, 73 and 74 of the ECU plug go to any of your chopped wires at the C101, it should be fairly simple to work out what's wrongly connected and to where it should be connected.

Post Thu Apr 25, 2013 8:34 pm

Brianmoooore wrote:
E30REDD wrote: This is because some idiot have been mixed Black/White with White/Black cables.
This is beginning to look like what the problem is. We're nearly there now - once you've determined where 8, 9 and 14 of the C101 actually connect to at the ECU plug, and whether 17, 73 and 74 of the ECU plug go to any of your chopped wires at the C101, it should be fairly simple to work out what's wrongly connected and to where it should be connected.

8 -------> 73
White --> 17

Okay, this white wire connected to 17 is a good sign, but I'm too confused to really think. I know this white cable should go to pin 8.

And to pin 8 there's currently a Black/White wire.

But why the fuck is pin 8 and pin 16 (both on the c101) white/black? Just to confuse me even more?!

Also, before I removed the ECU plug I removed the minus cable from the battery, just for safety reasons. As the car has no power now the SI-batteries are supplying the dashboard with power. Is it okay to leave it like this for 1-2 days since I cba plugging back the ECU plug tonight because I have to do some measurements on it tomorrow.

Post Thu Apr 25, 2013 8:56 pm

Cluster should be fine running on its internal batteries only for a year or so. If the batteries fail over night, then they are definitely in need of changing!
An E30 C101 should have a black/white wire on pin 14, and white/blacks on pins 8 and 16.
The one on 16 has no connection on the body side of any E30 I've looked at, and I have in my notes that it's something to do with diagnostics - I think it goes to a pin in the diagnostic plug only.
It only gets confusing when someone chops all the wires and tries to attach them (wrongly) to what is probably an E36 loom.

Post Thu Apr 25, 2013 9:00 pm

Brianmoooore wrote:Cluster should be fine running on its internal batteries only for a year or so. If the batteries fail over night, then they are definitely in need of changing!
An E30 C101 should have a black/white wire on pin 14, and white/blacks on pins 8 and 16.
The one on 16 has no connection on the body side of any E30 I've looked at, and I have in my notes that it's something to do with diagnostics - I think it goes to a pin in the diagnostic plug only.
It only gets confusing when someone chops all the wires and tries to attach them (wrongly) to what is probably an E36 loom.

Yea...

Since my fuel rate input wire is white it should be connected to pin 8. Does this mean my loom is coming from an E36? Or are there E30 looms with white wires for fuel rate input?

Post Thu Apr 25, 2013 9:09 pm

This pic, I guess I should weld the following:

Black/White with Black/White

White with White/Black

Then my economy meter should work?!

Post Thu Apr 25, 2013 9:36 pm

E30REDD wrote:This pic, I guess I should weld the following:

Black/White with Black/White

White with White/Black

Then my economy meter should work?!

If that is the same as this, then yes:

Brianmoooore wrote:
Pin 8 should go to pin 17 (possibly a white wire)
Pin 9 should go to pin 74
Pin 14 should go to pin 73

Post Thu Apr 25, 2013 9:47 pm

Brianmoooore wrote:
E30REDD wrote:This pic, I guess I should weld the following:

Black/White with Black/White

White with White/Black

Then my economy meter should work?!

If that is the same as this, then yes:

Brianmoooore wrote:
Pin 8 should go to pin 17 (possibly a white wire)
Pin 9 should go to pin 74
Pin 14 should go to pin 73

No, it's not like that because pin 8 is connected (wrongly) with a Black/White wire. This Black/White wire should go to pin 14. If I change the Black/White wire from pin 8 to pin 14 it will be all good. This will leave pin 8 with no wire at all, and it will be solved by connecting it to the white wire which goes to pin 17 in the ecu (for the fuel rate input).

Sooo, as it is now pin 14 (Speed signal out to ECU) shouldn't be working at all now. But since my car works it seems like it's being connected properly anyway. WHAT?!

Am I right? Im so damn sick in my brain at the moment. I'm going to bed. Thank you for your help, I will be back tomorrow. I bet I will have nightmares about wire colors and pin numbers.

Post Sat Apr 27, 2013 11:51 am

I fixed it and everything is working fine. Thank you Brian

Post Sat Apr 27, 2013 1:56 pm

E30REDD wrote:I fixed it and everything is working fine. Thank you Brian

Except the fuel gauge apparently! That one should be a bit simpler to sort, hopefully.