starting problems no voltage to coil

[aquapool]

90 535i m30
suddenly stopped cranking. drove to destination fine. upon leaving hard time starting. would cut off during idle. now she turns over but won't start. Fuel issues are o.k. No spark from plugs when I pulled them out. I am not getting any reading on the low voltage side of the coil. Should be twelve volts with ignition on if I'm correct. 0 fault codes came up with scanner tool.
Anyone know where to go from there.

[bill g]

Check that battery terminals and engine ground strap are clean and tight. Use a digital multimeter to check battery voltage - should be at least 12.6v standing (engine off), and should not drop below about 10v while cranking for 15 seconds - do not crank any longer than this. If either of these voltages are low it indicates the battery is undercharged or faulty.

Bill G

[aquapool]

Check that battery terminals and engine ground strap are clean and tight. Use a digital multimeter to check battery voltage - should be at least 12.6v standing (engine off), and should not drop below about 10v while cranking for 15 seconds - do not crank any longer than this. If either of these voltages are low it indicates the battery is undercharged or faulty.

Bill G

12.02V from the battery while the engine is off. It is probably drained a little from trying to get her started a few times. Still 0 voltage to the coil with the ignition on. I would really hate to tow her to the local shop.

[bill g]

12.02V indicates about 25% charged, not much use for anything. Try charging the battery and then re-test.
Another possibility is faulty ignition switch or related wiring.
You could try tracing back from the coil low voltage supply wire to find the problem but you really need circuit diagrams (such as in Bentley manual). First place to check is ignition switch - coil low voltage supply is green wire.

Bill G

[BillionPa]

i put my bet on a faulty ignition switch.

[aquapool]

12.02V indicates about 25% charged, not much use for anything. Try charging the battery and then re-test.
Another possibility is faulty ignition switch or related wiring.
You could try tracing back from the coil low voltage supply wire to find the problem but you really need circuit diagrams (such as in Bentley manual). First place to check is ignition switch - coil low voltage supply is green wire.

Bill G

There is 11.51v coming off the coil low voltage supply on the ignition switch.
I would also like to thank you for your help on this problem. At the rate I'm going with all these repairs I hopefully will be able to contribute to this board soon.

[aquapool]

Finally found a bentley manual and tested the coil and it was o.k but the ohms on the high voltage side were a little higher than normal. according to bentley it's supposed to be 6.0k but it came up 9.0k. Next I tested the crank position sensor and nothing, no ohm reading. Time for a new one. Any suggestions on where or what brand I should purchase? BMA has a HELLA for $92.

[BillionPa]

hella for the win.

also, your ignition coil is probably a good 17 years old, i would just get a new one.

[gmannino]

If your not getting 12 volts at the coil, there is your problem. Check all your fuses and fusable links. If worse comes to worse, jump from a known ignition source to the coil, this will allow your car to start. 12 volts is plenty to get your car started unless you have had troubles starting previously.

Send 12 volts to the coil and it will crank. If not, swap coil.

[bill g]

Aquapool as far as I know there were two different types of stock coils used in E34 535. If yours is the one not shaped like a small coke can then it is the same as mine. The resistance in the high voltage side of mine is also 9k ohms, which I think is correct. The figure given in the Bentley may be for the other type of coil.


Bill G