Thread: V8 Discovery II Ignition Coils

Hi bee utey,

How do you go about testing the coil voltage pulses with the SXE-Probe?

Do you connect the probe’s positive terminal to one pin connector and the probe’s negative terminal to the vehicle's body, or do you connect the positive and the negative terminals to both pin connectors?

LRT

Originally Posted by LRT

Hi bee utey,

How do you go about testing the coil voltage pulses with the SXE-Probe?

Do you connect the probe’s positive terminal to one pin connector and the probe’s negative terminal to the vehicle's body, or do you connect the positive and the negative terminals to both pin connectors?

LRT

Each D2 coil pack is actually 2 coils. Test each coil pulse wire separately. Both coil packs share the same 12V supply from fuse 14, the negative side of the coil should pulse to a low voltage for every firing pulse. If they remain at 12V they aren't being pulsed. That's the plain red and plain blue wires on one coil pack and the pink/black and white/blue on the other coil pack.

Thanks bee utey,

Do you need to run the engine to test the coil voltage pulse?

Should I spike the probe into each wire, or disconnect the connector?

LRT

In relation to the question of ECUs and transmissions. The ECU is generic between trans but is coded to the VIN, not matched and you won't be as far along as you are. The Auto has it's own ECU but I can't see one needed for a manual though the one controlling ABS/HDC/TC will be there but stand alone from transmission.

However IF someone has fitted a auto ECU and got it working the code could be from remnant info required to start. In this case not seeing a clear signal from the auto ECU that it's in N/P then no start or at least a fault that it's not there.

FWIW I'm in the middle of researching both replacement coil packs and ECU's for mine to move them from the ridiculous place they are and get some back semblance of control over ECU for fuel/timing etc plus make it work better with the larger engine.

Originally Posted by LRT

Thanks bee utey,

Do you need to run the engine to test the coil voltage pulse?

Should I spike the probe into each wire, or disconnect the connector?

LRT

You are testing for what makes the sparks, aren't you? The engine needs to be rotating, ignition on, plugs connected or there will be no pulses to measure. If it doesn't run then you use the starter motor. If it runs you already know there are pulses because the coils are producing sparks!!

Hi clubagreenie, thank you for the helpful information about the automatic transmission ECU.

I checked the side panel on the passenger seat, but there is no ECU.

The Hawkeye diagnostic tool shows that the BCU is programmed for a manual transmission.

Also, when selecting the auto transmission menu on the Hawkeye, it cannot establish a connection.

LRT

Hi bee utey, I tested the four ignition coils, the results are as follows:

Blue wire C0638-2: 5Hz, 0%, 12 volts

Red wire C0638-8: 0Hz, 0%, 0 volts

Pink & Black wire C0638-6: 4Hz, 0%, 0 volts

Blue & White wire C0638-7: 4Hz, 0%, 12 volts

What are the requirements for the pulses to be correct?

The Hz readings are steady and do not fluctuate.

How do I interpret these readings?

LRT

The first reading of 5hz is consistent with the engine cranking at 300rpm. The second is consistent with you reading your bare finger. The third and 4th are consistent with the engine cranking slower. The other numbers are meaningless unless you know what it is you are actually trying to do.

I don't think this is going to work, you need someone who understands engines to visit you. I can't give you the experience to work out what the readings mean. Sorry.