NEED HELP FAST - obc issue

[Bimmerfanatik]

those plugs are on the passenger side, by the ecu. The box that went bad on me was the large OBC relay box, that has the 2 green plugs going into it.

right, I know those plugs on the passenger side. Is there anything that needs to be connected on the driver's side?

I swapped the box you're talking about with a known good one, and still no luck.

Maybe the fuel pump decided to shit out on me...

[rs4pro3]

nope nothing needs to be connected on the driver's side

[Bimmerfanatik]

nope nothing needs to be connected on the driver's side

ok, talked to my friend who was working on it last night.

According to him, there was not power at the transfer pump. But, there was at the relays...

[wastedincome]

Ok Scott
Checked power at the main relay w/ pin 87 neither PIN 87 get power w/ key on

DO have power @ pin 86 & 30 w/ key on

Fuel pump Relay has one pin 87 and DOES have constant power. When jumped FP realy pin 87 to Main Relay pin 87 car starts.

Also tried switched power from Radio to fuel pump car also starts

Ok We have:
Switched power @ ECU w/ green wire
Switched power @ Ign. Coil @ grren wire
Note: OBC has been bypassed

[Dave]

Fuck the OBC!!!!!

Glad to hear its running.

Truth be told, I miss my OBC.

[wastedincome]

Fuck the OBC!!!!!

Glad to hear its running.

Truth be told, I miss my OBC.

Dave I like the new sig & new additions on the car

The car CAN start but the true problem is NOT found yet. Its ONLY ran w/ jumpers.
Help and idea's are STILL needed

I guess its not in the OBC cause ADAM say that that would kill spark too (which I didn't know).

[Bimmerfanatik]

Dave I like the new sig & new additions on the car

The car CAN start but the true problem is NOT found yet. Its ONLY ran w/ jumpers.
Help and idea's are STILL needed

I guess its not in the OBC cause ADAM say that that would kill spark too (which I didn't know).

What he said. For now we've got the fuel pump relay pin 87 jumpered to the main relay pump 87, and everything is hunky dory. I just want to know if there's something we can do other than this, a problem that could be causing the above situation.

[rs4pro3]

well on the relay pin 30 is constant 12 volt, pin 85 is ground, on the main relay it's constant, and on the fuel pump relay it's triggered by the ecu, pin 87 is what is being driven by the relay. In the case of the main relay this is the ECU via pin 35 and 18. Then the main relay also powers the fuel pump relay via 86, and the injectors via the Red/white wire. Pin 86 on the relays is the trigger to switch the relay on and off, the main relay is triggered by the ignition switch(running threw the OBC harness where equiped), and then the main relay triggers the fuel pump relay.I'd go threw each relay and check for the proper voltages and grounds
Main relay
Pin 30-constant 12volt
pin 85-constant ground
pin 86-switched 12volt
pin 87-12volt out of the relay(has to be checked by backprobing the relay with it installed)

Fuel Pump relay
Pin 30-constant 12volt
pin 85-switched ground coming from pin 20 on the ecu
pin 86-switched 12 volt provided by the main relay
pin 87-2 volt out to the fuel pump.

I wouldn't run long with the jumper as relays switch on and off at a very high rate of speed, with just a jumper wire in place it will heat up and possibly fry the circuit.

If I read correctly with the relays removed your are getting a constant 12 volt threw pin 87 on the fuel pump relay?
With these types of problems you have to be very systematic and not just jump around testing different things.

[Bimmerfanatik]

well on the relay pin 30 is constant 12 volt, pin 85 is ground, on the main relay it's constant, and on the fuel pump relay it's triggered by the ecu, pin 87 is what is being driven by the relay. In the case of the main relay this is the ECU via pin 35 and 18. Then the main relay also powers the fuel pump relay via 86, and the injectors via the Red/white wire. Pin 86 on the relays is the trigger to switch the relay on and off, the main relay is triggered by the ignition switch(running threw the OBC harness where equiped), and then the main relay triggers the fuel pump relay.I'd go threw each relay and check for the proper voltages and grounds
Main relay
Pin 30-constant 12volt
pin 85-constant ground
pin 86-switched 12volt
pin 87-12volt out of the relay(has to be checked by backprobing the relay with it installed)

Fuel Pump relay
Pin 30-constant 12volt
pin 85-switched ground coming from pin 20 on the ecu
pin 86-switched 12 volt provided by the main relay
pin 87-2 volt out to the fuel pump.

I wouldn't run long with the jumper as relays switch on and off at a very high rate of speed, with just a jumper wire in place it will heat up and possibly fry the circuit.

If I read correctly with the relays removed your are getting a constant 12 volt threw pin 87 on the fuel pump relay?
With these types of problems you have to be very systematic and not just jump around testing different things.

The relays are in place as normal. We have just jumped the switched 12-volt signal found at the fuel pump relay and jumped it to the switched 12 volt at the main relay, which we didn't see coming through. This gave the main relay switched power, and the car runs fine.

I'm not sure I understand the issue with the jumper the way it sits - the main relay needs to see 12v switched - if it gets it from the fuel pump's 12v switched, what's the big deal?

Obviously, I want to figure out why the main relay is not getting switched 12v. That's the point of continuing this post :) I just know that sending a switched 12v signal to either the main relay or to the fuel pump directly makes the car run as it should.

[rs4pro3]

pin 87 is not the switching power for the relay, if you had to jumper the pins of the relays in that matter that means one of them is bad. I thought you had completly removed the relay and just used a jumper wire in place of the relay.

[Bimmerfanatik]

pin 87 is not the switching power for the relay, if you had to jumper the pins of the relays in that matter that means one of them is bad. I thought you had completly removed the relay and just used a jumper wire in place of the relay.

hrm. You told me in an above post to look for switched power at pin 87 for both relays. I found it at the fuel pump relay, but not at the main. So we jumpered the two pins (their corresponding wires to be exact) while keeping the relays intact. Things seem to be working perfectly!

[rs4pro3]

it's switched in a way but by the relay, pin 87 is power coming out of the relay to drive what ever accesory the relay is for. If you are getting voltage out one, but not the other and all the other pins have what they should then the relay is bad.

[Bimmerfanatik]

it's switched in a way but by the relay, pin 87 is power coming out of the relay to drive what ever accesory the relay is for. If you are getting voltage out one, but not the other and all the other pins have what they should then the relay is bad.

I swapped the relays with a known good set from another car, still no luck. Hm.

[wastedincome]

Well crisis is over now. The car is in the hands of its new owner last I heard.

[Bimmerfanatik]

Well crisis is over now. The car is in the hands of its new owner last I heard.

This is true. Thank god :)