Spark plug wiring

[acspecialists]

I'm going through the harness while waiting for DUDMD to return and provide a new DME. All of the grounds for each bank are grounded to the valve cover. Additionally they are connected to a small 1"x 1/2" black device and to a group of green wires. I have thoroughly reviewed the Bentley manual and can't find or identify the small device and connection. I assume it is a diode but I would like to be sure. I have no spark and I'm checking all of the wiring and grounds. Anyone know what this device is and it's function? It is located under the wiring compartments on the engine, one for each side.

[Timm]

The facelift loom (for the M62TUB) has GREEN wires to the coils which should be permanently at 12V when the ignition is switched ON - supplied by the unloader relay K6326 - that's the place to start. The DME grounds the other side of the coil primary through the BLACK/xxxx wires (BLACK/BLUE, BLACK/YELLOW etc).

The secondaries are grounded through BROWN wires - on the pre-facelift these were joined to a resistor before being grounded, again through a BROWN wire. There is no diode or resistor in the ignition coil wiring on the M62TUB harness

[acspecialists]

KIMG0002.jpg
Here's a picture of the little bugger. It is grounded on one side and I guess the other side(green) is power. You can see the bundles of green and brown wires. I have checked the wires back to the DME and the grounds. Seeing this little device threw me off. If it failed open or shorted would it not cause the spark system to fail?

[Mayorchuck]

Never seen that before but it has a BMW number on it. Doesn't pull up on realoem. Have you check the fuse carrier. Fuse 5 goes to the uniloader. If you haven't checked it before, it's the box next to the uniloader with 5 fuses in it.

K6326, X6326


rear RH side of engine compartment in E-Box

K6326	Unloader relay terminal 15
X6326	Component connector (9-pin, Black), Unloader relay terminal 15

[acspecialists]

Yup, all fuses pulled cleaned and tested. I looked on Realoem and only came up with a harness. Checking the harness wire by wire to cover all of the bases. I don't want to cut anything unless I have to. Then a simple test would confirm what type of device unless it's dead. My only guess is a high value resistor from power to ground. The DME may want to see a fixed current flow to confirm a good system. They do this in automation to tell the system when there is a broken wire.

[Timm]

After a bit of research - the strange device is a capacitor which runs between 12V and Ground - as it is probably a ceramic device I would doubt if it has died.

[acspecialists]

Of course, odd to see one on a DC system. Unless it was shorted there would be no physical connection. I would guess that BMW was just trying to hold peak voltage. It makes sense that they got rid of it. If I keep having problems with spark I may test them.

[Timm]

More likely it is there to reduce radio-frequency interference