2002 Bmw x5 3.0 crank no start

[mic2damgood]

I have recently found out that i have no fuel pressure. So i have checked for voltage at the fuel pump. Had no voltage. Check for fuse and fuel pump relay. the fuse was good and the relay had power fuse F47 but no power to F51. which feeds alot of other circuits but also is the coil side power on the relay. So i traced back on red/wht wire where it splices in to supply power to one of the fuses on the engine electronic fuse carrier. Then it branch into engine control module relay. This engine control module relay (presume is the main relay) either has no voltage or isnt working. I have attached some wire schematic on this post if you guys have any thoughts.

my question is:
What supplies power to the main relay? This 60A fuse on the schematic, where is it located?

[andrewwynn]

The v8 has some magic power unit with fuse under DME I didn't see similar on the 6 so I'm not sure. There are relays on the back of the fuse panel in the glove box that's my bet


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[mic2damgood]

Originally Posted by andrewwynn

The v8 has some magic power unit with fuse under DME I didn't see similar on the 6 so I'm not sure. There are relays on the back of the fuse panel in the glove box that's my bet


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I guess I can trace back the red wire. The 60 amp fuse is what powers the relay. I see if I can trace is back by pulling the wire.

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[mic2damgood]

So remember that brown and white wire that was broken? Well, it was important. It was connected to the main relay and was broken from the DME. The main relay did not have power, the DME supplied the ground. As soon i connected that wire to the Dme. I then had power on fuse F51, schematic below, i belive this is what bring power to the fuel pump relay. But as soon as i turn the key to the ON position, F51 10A fuse blows. I think i have a electrical short somewhere. What do u guys think?

In the picture:
There are 3 wire that get power from fuse F51.
wire no 2= goes to fuel tank leakage diagnosis module
wire no 7= supplies power to secondary air injection pump relay coil
wire no 18 = supplies power to secondary air mass meter

I have disconnect the fuel tank leakage and secondary air pump connectors fuse F51 still blow.

I dont know where the secondary air pump relay is. Any help on where that would be appreciated.

Would F51 fuse being open. Would the open from the fuse disconnect voltage from the fuel pump relay?

Any thoughts would be most welcomed.

[andrewwynn]

Measure Ω from pins 2-7-18 to ground. It should show low Ω indicating a short.

You'll have to disconnect the connector to measure them independently to determine which is shorted.

The "ground?" Is power to some other subsystem.



62 is the relay for SAP. Pulling that should remove it from the F51 chain if there is a short on the control line of the sap relay and that 62 is an actual relay not the fuse for the relay you can eliminate from the equation

[mic2damgood]

Originally Posted by andrewwynn

Measure Ω from pins 2-7-18 to ground. It should show low Ω indicating a short.

You'll have to disconnect the connector to measure them independently to determine which is shorted.

The "ground?" Is power to some other subsystem.



62 is the relay for SAP. Pulling that should remove it from the F51 chain if there is a short on the control line of the sap relay and that 62 is an actual relay not the fuse for the relay you can eliminate from the equation

Thanks adrewwynn
I will try this tonight.





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[mic2damgood]

Just FYI...

I have also found out from a schematic that fuse F51 supplies power to ABS/DSC module and steering angle sensor.
It also said on the glove box cover where the fuses are labeled. The fuse F51 is connected to obdII. But I haven't found it on a wiring schematic yet.


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[mic2damgood]

Update
I found what was blowing f51. I found the secondary air injection pump relay and removed it. Fuse didn't blow. But then I realized that the relay was the wrong color. It was yellow like the one pictured. But I needs to be pink. I ordered a relay online. I will install it when it gets here later this week.

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[wpoll]

Fun job - following after some butcher has been at the car... good on you for rescuing it.

[andrewwynn]

Odds are the relay is wired the same. Unless their is a defective in the relay their is more likely a problem in the wiring somewhere but awesome if you've found a way to stop the fuse from blowing you know which path to chase the fault.

If you can keep the fuse from blowing now maybe you have power to the DME to get reading via obd.

I was recently working on a Volvo replacing the radiator and I forgot to reconnect a connector and had a no start condition. I think the connector included the camshaft position sensor. Make sure all the mission critical sensors are connected.