5/1994 M50 swap into 1989 325iC (wiring harness)

[smooth]

actually correction...the flywheel is not original it came off the 97 m3 that the tranny came from


Sent from my iPad using Tapatalk

[justin_l_]

Cut back the shrink wrap and see what color they are.

[meanEG]

you do have the ground hooked up to the engine right? your battery is in the trunk? either way i would try grounding the engine with jumper cables to clean steel, or the negative battery post, or do a voltage drop while holding in crank position

[meanEG]

in know there is a picture here on the r3v of your question regarding the 2 wires. i ran into before. you need to open your search keywords. I have a feeling you need to study how to read wiring diagrams a little more. more than likely you have a simple problem. have you check voltage to other components to verify that your ground where you put the battery in the back is good? this sounds like a ground issue, i know oyu have something else going on though. what i am trying to say is that these symptoms sound like a poor ground, not permitting the starter to spin

[mpowerful]

Lets clear this up.

Terminal 50 is heat from the key. That pulls in the 12v contact for terminal 30 which is your two main wires and runs the starter motor.

Terminal 30h grounds out when it sees 12v from terminal 50 basically unloading those accessories by giving those relays a path to ground.

[jlevie]

Covering several things mentioned...

Pin 7 of C101 goes to the Hot in Run and Start circuit which also goes to one side of the unloader relay coils. Pin 15 goes to the other side of the unloader relay coils. So with the ignition on (and the battery disconnected) there should be connectivity between pin 7 and 15 on the body side of C101.

Pin 18 of C101 is the Hot When Starting circuit and has to go to the starter's solenoid control lug (black wire with yellow stripe). Pin 7 is the unloader circuit and goes to the unloader switch in the starter. That switch is closed when the solenoid isn't energized and grounds the unloader relay coils, causing the relays to close. On an E30 starter the solenoid and unloader lugs are different sizes and I think that is also true for the E36 starter. Which means that one of the wires will only go on one of the lugs. So if you match up the wire lug with the correct sized starter lug the starter is correctly connected.

In case there is any doubt a test light will tell you which wire is which. With the wires disconnected from the starter the unloader wire should have power when the ignition is on and when the key is turned to start. The solenoid wire will only have power when the key is turned to start. With that wire connected to the starter solenoid lug if you hear the solenoid click when the key is turned to start, but the starter doesn't run, the starter isn't grounded, there is a high resistance in the stater's power connection, or the starter is bad. The starter is grounded by the block, so the engine to frame ground strap must be in good condition and making good connections. High resistance in the starter power circuit will be a bad connection somewhere.

You can test for a ground or power problem with a volt meter. Using a good chassis ground the voltage at the starter power lug should only drop slightly when the key is turned to start. At the same you should not see any voltage between the starter body and ground.

[smooth]

Thank you to everyone contributing and especially thank you to Jim for taking the time to provide a fairly lengthy explanation about what's happening, or should be happening, with the circuit.

I'll go test voltage now and update the thread. I see now that I misunderstood some earlier threads and that my windows shouldn't operate when the wires are in their correct locations.

The fact that it doesn't work that way (the windows operate when I am trying to crank with the wires connected to the starter correctly) points to either a bad ground or a shorted solenoid, if I'm now understanding correctly.

I'm not sure why the unloader circuit would work correctly when I moved the unloader ground wire to the solenoid control lug (with the trigger wire) but that's what happened.

I'll be back in a few with the test results...

[e30rapidic]

send me a PM with your email address if you want to see my wiring diagram. I have a 10/86 build date with S50

[smooth]

Thanks for the offer e30rapidic

Checking voltage at the main lug I only get a .3 drop when I tried to crank the starter. Checking voltage at the solenoid lug I get a 3 volt drop when trying to crank.

I get .0134 volts between ground and starter body when trying to crank.

Testing resistance between ground and the solenoid lug I have .4 with key in off and 22 when I turned the key that dropped to 19.3 when I held key in start position.



Sent from my iPad using Tapatalk

[meanEG]

Thanks for the offer e30rapidic

Checking voltage at the main lug I only get a .3 drop when I tried to crank the starter. Checking voltage at the solenoid lug I get a 3 volt drop when trying to crank.

I get .0134 volts between ground and starter body when trying to crank.




Sent from my iPad using Tapatalk

you are testing on the battery terminal right? not the cable end or lug, but the post on the battery? you are going to have to use a jumper wire obviously. ohm test with out load, voltage drop while loaded. this is all i want to know. the others can help do the rest of the wiring diag.

Go from the starter body to negative post and crank. go from the starter post to the battery post and crank

[e30rapidic]

check your e-mail

[smooth]

wiring was good. starter was toast. $110 dollars from a local rebuilder and she's up and humming (sorta). idling, bit rough, but still need to hang the exhaust and get all the throttle linkage sorted. somewhere along the way I need to figure out how to adapt my 10mm lines to my 12mm master cylinder...at least if I want to stop that is ;)

[328ijunkie]

We sell adapters for MCs