M30 wiring

[azzkikr]

I am finally getting to the wiring on my car. I have everything hooked up and everything seems to be correct. I cant start my car though. I dont get any power to the starter from the relay. If I short the battery plug and the ground plug I get the starter to turn over. However if I try to get the starter to turn by using the key I get nothing. From my simple analysis the starter relay is initiated on pin 18 on the engine plug and the E30 chasis plug. I get voltage to pin 18 on the car harness. I just dont get anything to the starter through the computer. Are there any satefy controls in the ECU that prevent the car from starting. My engie is from a 1990 535i 5-spd and as far as I know it should just engage the starter when the key is turned.
Also what cable should go the the little plug on the alternator? I have the starter in series with the alternator. I just ran a big nasty wire across from the starter batter lead to the alternator lead. That should be fine right? But where does the little cable come from? I did try starting the car with and without the alternator connected just to be sure that wasnt causing a problem.

I do get power to the console and it lights up like a christmas tree. Pretty much every light turns on. The check engine light even flashes so I guess that is a good sign. How do you enable the check engine fault code to be displayed? I tried to do the tap the gas pedal 5 times in 5 seconds after turning the car on but I didnt get anything. I even tried open the throttle by hand 5 times in 5 seconds but I still didnt get anything. Where does it pickup the signal for that anyway. That is how to get the fault codes right?

Its long sorry.... just lots of wiring still to be done. Any pins I should switch for sure on the plug?

EDIT:
One more thing. What to do the plugs in the glove box connect? There is a 4pin plug on the E30 and the M30 wiring harness has a 4pin plug but the connectors are different. What do they do? There is also a couple little 2 pin connectors in there to...what are they for?

[azzkikr]

Okay I got my wiring worked out. But now I am only getting slow crank speed. It looks like the starter might be shot because I checked the wires and everything seems to be in place. I am going to check the current and voltage tomorrow. How can I check to see if the starter is dead? Also if I have a starter from the E30 1990... will that turn the big motor? I see the part numbers are different but I think the physical dimensions are the same. Will the start be enoght to start it once? I am going to try that either tomorrow or wednesday when I get some time but any heads up would be good

[rs4pro3]

Sounds liek your battery is low, or your starter is dead, take the starter out and take it to autozone etc.. they can test it, and the e30 starter will not work.

[azzkikr]

I am going to check the voltage across the starter first but it looks fine via the headlight test. I am sure I will need a new starter.

But do you know what the "extra" plugs in the glovebox that are outside the ECU go to? That is about the last unknown in the wiring system for me right now.

[rs4pro3]

one of them is for the AC and the other on some cars is for the OBC fuel cut.

[azzkikr]

Tell me more about this OBC fuel cut. I was reading a post about it that Jordan had and when I got the the very end he said to see what I did read this thread.... and that thread is a no go. All that for nothing :) As an aside I got everything working on my car and I finally got it started. I traced a million wires today and I found a starter kill switch hidden under the dash. That was the culprit. I clicked the switch and the car started right up. Of course I had to short the fuel pump relay to get it going.
My new gremlin is the fuel pump never comes on when you turn on the car. I checked the relay and it works fine. I get 12V on 85 and 86 and I have 12V on 30 or 87 whichever the lead was on, fuel pump is on the other. Anyway it should have current through to the fuel pump. I tested the relay and it clicks and passes continuity tests when closed. I found that the only thing that is not working is the ECU wire, I dont remember the color. If I short the ECU pin to ground then current flows through across relay. The problem seems to lie on the ECU side of the circuit. Is the ECU supposed to ground the relay? Are one of those extra connectors in the glove box supposed to ground the ECU or something? Any ideas would be helpful

[rs4pro3]

Ya the ecu provides ground control for the relay, when I first did the m30 swap I had that exact same problem, turned out it was an internal problem with the ecu, I could make it work by grounding the relay directly, but then when you shut the car off the pumps would still run, I ended up replacing the relay. I don't know if that's your problem or not, I have to run to classes now but when I get back I'll look over some diagrams and reply back to this post.

[azzkikr]

I was only able to get the car running by shorting the relay. If it comes down to it I will just run a switch to the dash. I am capable of starting the fule pump manually and I dont need a computer to control it. I was just worried if the computer wasnt working for the fuel pump there might be other areas where it will fail too. I am going to test this out this weekend. Did replacing the relay cure the problem or did you just short it out of the circuit?

Do you have the wiring diagrams in electronic format that you could send to me. The Bently is alright but the wiring diagrams are pretty lame. Espescialy the E30 diagrams... I think they are all hand drawn.

Looking forward to your response

[rs4pro3]

I replaced the ecu itself, I traced it down to the ecu plug directly, internally the ECU provides the ground for the relay and it wasn't. This was an L-jet ecu so it may be different.

[azzkikr]

Yeah that is where I am at. The ECU is supposed to make the ground but it is not. Do you have the wiring diagrams at all? Those would be vvery helpful. Mine is a Motronic ECU and I guess I will have to find a spare to see if that cures it. Otherwise its back to the good old fuel pump switch on the dash

[rs4pro3]

I've got the factory ETM manuals, I'll see if I can email the pages somehow.

[Psychomofo]

While we're on the subject of M30 wiring. I have a couple questions, or problems rather. Mine is an '89 M30 from an automatic car. Turns over just fine, and even runs the fuel pump correctly. It starts and runs good. Got 2 problems though. My tach. doesn't work, and neither does my temp. gauge. I swapped out coolant temp sensors with the factory '84 318 sensor, but it didn't work either. Any clues on this one?

[azzkikr]

Psychomofo which wiring harness are you using? Are you using the harness from your M30 auto or are you using the E30 harness?

[Psychomofo]

Well, since the car is a 318 I had no choice really. I guess basically what I'll have to do is trace down the wires to figure them out for my tach., but as far as the coolant temp gauge not working...well, I don't really know right now.

[azzkikr]

Well, since the car is a 318 I had no choice really. I guess basically what I'll have to do is trace down the wires to figure them out for my tach., but as far as the coolant temp gauge not working...well, I don't really know right now.

I can say on my car, 1990 325i, the E30 wiring harness is setup to receive signal on pin # 4 for the coolant temp sensor and on pin #9 for the tach, engine speed. The simplest thing for you to do would be to find out which pin your temp sensor and engine speed sensor are sending on, from the engine side. Just do a line continuity test from the sensor plug (brn purple??? I believe) to the engine harness plug. With the lead attached to the plug attach the other lead to each pin on the plug in sequence. Whichever line you get continuity on is the pin for the engine harness. I dont know if the 84 318 uses the same pin mapping as my 90 325 but if it does then you need engine speed and temp sensor to be on #9 and #4 respectively.

There is a good russian site with lots of wiring diagrams... anyone remember what that is? I forgot but it was very helpful when I was working out my wiring.

Once you are certain that the pins between the engine harness and the chassis harness are the same then test it. If it works great if not then you need to check that the sensor is sending a signal in the range that the gauge can understand reasonably. I heard if you use the M20 sensor you wont have a problem. I know you did this but check that the correct signal is getting to the sensor first, by the above method. Post back here with your results. I am curious if the pin mappings are the same across the years/models/engines.