Car cranking, but not starting(Now with spark!)

[ST1G]

ok without reading thru the last ten pages it seems to me you swapped in a main relay at some point ,just to check things pull the relay and look at the numbers on the bottom are there terminals labeled 87 and 87a ? also are there corresponding wires in each female portion of the relay socket? if yes ohm test between 87a and 87 it should be open if its a standard 5 pin relay .

find your original main relay and compare the pin numbers and orientation compared to the one you installed to see if there is a difference . looking at the diagram there are two pin 87's which if they are not wire into the same socket means the relay that needs to be used for the main is not a standard 5 pin and should have two pin 87 (no pin 87a) and that they are both powered when relay is engaged ,if you have the wrong relay in there it could be causing the readings your getting on pin 37...

I swapped the relay out to test it, but after a different working relay didn't work I swapped the original relay back in. It is a 5 pin relay. Relays can only be put in one directional, and are standardized. Keep in mind I jumped pin 87 and 30 on the socket. Yesterday I pulled the socket off the clip and the Red/Yellow and Red/blue both come from the same socket on the relay, meaning that pin 87 is supplying both. When I jumped the relay I verified that I was getting 12v from pin 30, to 87.

[spdracrm3]

ok without reading thru the last ten pages it seems to me you swapped in a main relay at some point ,just to check things pull the relay and look at the numbers on the bottom are there terminals labeled 87 and 87a ? also are there corresponding wires in each female portion of the relay socket? if yes ohm test between 87a and 87 it should be open if its a standard 5 pin relay .

find your original main relay and compare the pin numbers and orientation compared to the one you installed to see if there is a difference . looking at the diagram there are two pin 87's which if they are not wire into the same socket means the relay that needs to be used for the main is not a standard 5 pin and should have two pin 87 (no pin 87a) and that they are both powered when relay is engaged ,if you have the wrong relay in there it could be causing the readings your getting on pin 37...

[ST1G]

Hmm.

Unplugged the ABS control under the dash, Here are results.

With abs unplugged.
37 12v


With ABS unplugged and 36 grounded

37 0V

Edit: realized I undid c131 not c101. I will see about undoing socket 20 at c101.

[ST1G]

Okay, here is my understanding.


Power off pin 86 of main relay goes to pin 38 (Red/blue) at ecu and ABS (Yellow/Red) goes to connector C101 first, then to the unit, then to the ignition. So I can just disconnect the ABS unit as a whole? Should I check voltage at C101 Red/Yellow?

[IMG][/IMG]

[ST1G]

"All my tests were done without the ECU connected as I can't test the pins with it connected."

you can take the small screw out of the back of 55pin ECU connector and remove the cover to be able to backprobe with the ECU connected (also alllows you to check/confirm wire colors at each pin)

I did not know that. That's good to know. I will do that after I check for ABS stuff.

[spdracrm3]

"All my tests were done without the ECU connected as I can't test the pins with it connected."

you can take the small screw out of the back of 55pin ECU connector and remove the cover to be able to backprobe with the ECU connected (also alllows you to check/confirm wire colors at each pin)

[ST1G]

reading back thru the last few pages of testing and results ,something is not right as you should not have voltage present on pin 37 if main relay is not engaged ,and looking at the diagrams the only possible source i can find would be thru the ABS control unit (unless the ECU is bad ,it can only be the other source as all devices on that circuit are grounded thru the ECU , which you have already swapped), what reading do you get on pin 37 to ground with the ECU disconnected? if there is voltage present it has to be the ABS or a short to voltage in the wiring , disconnnect the ABS controller and again test pin 37 for voltage?

I've got a spare 153 ECU. But like I said a few pages back. I have used this ECU in a friends car and it ran well. He even had a stroker set up. So, two 173 ECUs and the 153 in this car all have the same result of no spark.

I will test with the ABS as soon as I'm home from work.

I have been worried about voltage on pin 37 without the relay engaged, I knew that wasn't right.

what reading do you get on pin 37 to ground with the ECU disconnected?

All my tests were done without the ECU connected as I can't test the pins with it connected.

so,
Pin 37 voltage is as follows with the relay in:

With ignition on, and 36 NOT grounded 12v.
With ignition on, and 36 grounded to pin 2, 37 has 1v

[spdracrm3]

reading back thru the last few pages of testing and results ,something is not right as you should not have voltage present on pin 37 if main relay is not engaged ,and looking at the diagrams the only possible source i can find would be thru the ABS control unit (unless the ECU is bad ,it can only be the other source as all devices on that circuit are grounded thru the ECU , which you have already swapped), what reading do you get on pin 37 to ground with the ECU disconnected? if there is voltage present it has to be the ABS or a short to voltage in the wiring , disconnnect the ABS controller and again test pin 37 for voltage?

[ST1G]

i just posted that as a reference to identify pins that arent listed on other pinouts/diagrams. if you look at pin 37 on that diagram it shows the pin as "programming voltage" as is pin 39 but if you look at a FI diagram for 90 325i as posted it shows pin 37 as a voltage feed direct from main relay (pin 36 being the control of the main relay) so if your not seeing 12v on pin 37 there is a problem somewhere in that circuits Red/Blu wire .(notice a Red/Yly wire branches off to the ABS if thats shorted or has an issue it could bring voltage down ,might be worth disconnecting to see if voltage comes back to 12v)

i would trust an ETM over that ECU diagram ,like i said i posted it for reference only ,just trying to find as much info as possible ,knowledge is power....

Interesting, I thought it was schematic of where the 37 was getting power, or going.

So there should be direct power from the relay to pin 37 on the ECU. That is really what I was looking for. I was curious what else was the loop, whether a connector or splice. I wasn't sure which schematic in the Bentley would have it.

I also didn't know what wire came off the main relay that powered pin 87, so that answers that too.

Good point on the ABS wire, I'll check that out to see where that is going.

Side note, did a little testing at lunch, for kicks I jumped the relay.

With the main relay jumped (86 & 30) I am still getting 1v at 37 with 36 grounded. The same result as with the relay in place with 36 grounded. This is the same result I had been having

I also get the same result of 12v at 36 and 37 with the relay in and ignition on.

However, I am getting 0v at pin 36 with the relay jumped and ignition on.

I get 0v at 36 & 37 with the ignition off and the relay jumped.

[spdracrm3]

i just posted that as a reference to identify pins that arent listed on other pinouts/diagrams. if you look at pin 37 on that diagram it shows the pin as "programming voltage" as is pin 39 but if you look at a FI diagram for 90 325i as posted it shows pin 37 as a voltage feed direct from main relay (pin 36 being the control of the main relay) so if your not seeing 12v on pin 37 there is a problem somewhere in that circuits Red/Blu wire .(notice a Red/Yly wire branches off to the ABS if thats shorted or has an issue it could bring voltage down ,might be worth disconnecting to see if voltage comes back to 12v)

i would trust an ETM over that ECU diagram ,like i said i posted it for reference only ,just trying to find as much info as possible ,knowledge is power....

[ST1G]

here's a pdf schematic of a motronic 1.3 with all the pins identified ,might help identify additional pins

I guess I'm confused. I follow pin 37 for example (Because I don't seem to get the right voltage) and it takes me to different controller banks. Are these banks inside the ECU? I just don't know quite how to read it.

[itskingsteelo]

aint this some shit, for the past few days my car hasnt been wanting to start, i log on to r3v and bam!! i come across this thread.

[spdracrm3]

Is this an attachment? My phone shows it as a broken photo.

Edit: got it going in my chrome browser. I'm going to need an electrical engineer on that one....


Good thing my dad's one. Time to make a house visit.

well just look at the tabs on the side that identify the pins by number ,as to what each pin is .dont need to know what the electronics do internally

[spdracrm3]

pinnout for 4cyl

this is the pinout i have and mentioned for the 4cly ,like what would be nice to find for yours

[ST1G]

Car cranking, but not starting

here's a pdf schematic of a motronic 1.3 with all the pins identified ,might help identify additional pins

Is this an attachment? My phone shows it as a broken photo.

Edit: got it going in my chrome browser. I'm going to need an electrical engineer on that one....


Good thing my dad's one. Time to make a house visit.