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

[spdracrm3]

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

[ST1G]

Jumper the main relay and check pin 37 at the DME for battery voltage.

Replay was not plugged in all the way. With it plugged in fully get 11.88v at 37 with 36 grounded. I am still get 11.88v with out 36 grounded though. The relay does switch when I ground 36z

[solo318]

Jumper the main relay and check pin 37 at the DME for battery voltage.

[ST1G]

Pin 36 is supposed to have low voltage normally. It is the trigger circuit for the main relay. When you jumper 37 to pin 2 (ground) it should engage the main relay and send battery voltage to pin 37.

If you read the chart I posted with my values you see that when pin 36 is grounded I get a clicking. When it's grounded to pin 2, or jumped to ground.

when you jumper the pins you should listen for the relay to click. If you do not here a click then check for battery voltage at pins 30 and 86 of the main relay. If you here a click and still have no battery voltage you should jumper pins 30 and 87 of the main relay and check again for voltage at pin 37. If you have battery voltage at this point the relay is bad.

I've already checked voltage at pins 30 and 87 at the main relay, and I get the correct voltage! I also know that I have the correct voltage because in previous tests I get voltage from the main relay, over to the fuel pump relay, and over at the coil, with the relays installed.

If you do not you have an open on the red and blue? wire from pin 37 to pin 87 of the main relay.

I don't know what you're trying to say.

[solo318]

Pin 36 is supposed to have low voltage normally. It is the trigger circuit for the main relay. When you jumper 37 to pin 2 (ground) it should engage the main relay and send battery voltage to pin 37. when you jumper the pins you should listen for the relay to click. If you do not here a click then check for battery voltage at pins 30 and 86 of the main relay. If you here a click and still have no battery voltage you should jumper pins 30 and 87 of the main relay and check again for voltage at pin 37. If you have battery voltage at this point the relay is bad. If you do not you have an open on the red and blue? wire from pin 37 to pin 87 of the main relay.

[ThatOneEuroE30]

Sounds like a lot of work. I'd prefer tracking down the issue. I am looking at some diagrams now to see what's in the mix.

I just hate messing with wiring. So in my case I'd be swapping harness's aren't that hard imo. Carry on.

[ST1G]

Now it's how do you go about fixing that. My guess would be just swap out harness. For known good one.

Sounds like a lot of work. I'd prefer tracking down the issue. I am looking at some diagrams now to see what's in the mix.

[ThatOneEuroE30]

I have a strange feeling you're right.

Now it's how do you go about fixing that. My guess would be just swap out harness. For known good one.

[ST1G]

Gonna have to say the 1v at pin 37 is your problem.

I have a strange feeling you're right.

[ThatOneEuroE30]

Gonna have to say the 1v at pin 37 is your problem.

[ST1G]

Testing has been done. One highly notable thing, before I jump pin 36 and 2 (ground, activating main relay), I get 11.88v (The battery is currently producing 11.98v) after I jumper 36 & 2 I get only 1v at pin 37.

Also, with no jumper the test light is very weak at 36, but full power at 37. But both have the same 11.88v running to them.

No jumper 36


No jumper 37


Results

[ST1G]

Well, I found this. I'm thinking I might just go through it and test the whole harness? It doesn't seem like there is much there that I haven't already done. I'm getting suspicious of it being the signal being sent by the CPS not being correct.

[ST1G]

"I have a Bentley, I'm not sure if it has a pin out. Are you talking about on the hardness connector or the ECU pins?"

well from what i can tell so far your getting everything you need for the ECU to be working (other than scope testing CKP pattern),as you've already swapped ECU with another working car we can eliminate that only thing left is some signal to ECU that is incorrect causing it not to work. so basically you need to find a pinout for every pin at ECU and check each with it connected and make sure every signal/ground/power..... is right Are you saying check the pins of the harness with the ECU connected, or the CPS?

I have a pinout but its for a 318i and I'm not sure how much is common between the two models, another option is to go thru the ETM and find every pin and figure out what its supposed to be but this is difficult unless you really understand FI systems and their control. A good pinout will give values for key on, key off ,cranking so forth

I can search for a pinout. Farbin might have one. I don't think that the 318 is the same, the 4 bangers used a different ignition system (according to the Bentley).

couple other things i thought of today , from your video with the test light ,that isnt a smart LED test lamp is it (one that shows different color for ground or power) it just seem awful bright making me think it isnt an old style incandescent bulb version which you definitely need to do this test . a logic or smart test lamp wont work properly

i just happened to have a running 88 325iC in the shop today and have an old style Snap on test light and confirmed that during cranking it flashes distinctively (little hard to see once its running ) ,couldnt take a video though as i was on shop time ,i use this test on all other makes all the time but have never done a 325 so just wanted to make sure its a legit test and it is. on Hondas it will kill the bulb in the test light for some reason after about 10 flashes

also you never answered if any other ring end terminals were connected to the coil (neg term) possibly causing loss of control signal? (if an alarm or aftermarket tach is connected but shorting it will kill the coil signal)

I appreciate your helping me with this, I was skiing all week so I haven't looked for a pin out.

As far as the test light goes it's a $3 auto zone special. It's a incandescent bulb, not an LED. It's really nothing fancy, just a bulb with a negative clip, and a probe end.

The only thing that is connected to the coil is the green lead to power, and the black lead to negative. There are no other things connected to the coil. There is also no security system or any junk like that on the car.

I can also see about finding a scope so I can test the signal. I will try with the test light on pin 15 of the coil just for kicks.

[spdracrm3]

couple other things i thought of today , from your video with the test light ,that isnt a smart LED test lamp is it (one that shows different color for ground or power) it just seem awful bright making me think it isnt an old style incandescent bulb version which you definitely need to do this test . a logic or smart test lamp wont work properly

i just happened to have a running 88 325iC in the shop today and have an old style Snap on test light and confirmed that during cranking it flashes distinctively (little hard to see once its running ) ,couldnt take a video though as i was on shop time ,i use this test on all other makes all the time but have never done a 325 so just wanted to make sure its a legit test and it is. on Hondas it will kill the bulb in the test light for some reason after about 10 flashes

also you never answered if any other ring end terminals were connected to the coil (neg term) possibly causing loss of control signal? (if an alarm or aftermarket tach is connected but shorting it will kill the coil signal)

[ThatOneEuroE30]

Could you just try swapping motor harness's