Thread: V8 Discovery II Ignition Coils

If you have the coils off, you look at the 3 pin plugs and measure from the middle pin to the outers for primary resistance. The secondaries are measured across the output terminals between the two ends of each half of the coil, eg with firing order 18436572 you measure between the terminals for cylinders 1 and 6. BTW the resistance test won't find coils with internal insulation failure, only swapping with a known good s/h coil will do that.

Hi bee utey, thanks for the information on how to test the resistance of the ignition coils.

Can you test the coils when they are installed in the car?

Because there is no spark from either bank of the engine, is it likely that both coil modules have failed?

Or, is it more likely that the supply current to both of the coil modules have failed?

Do you know how to test the current that is supplied to the coil modules?


LRT.

Originally Posted by LRT

Hi bee utey, thanks for the information on how to test the resistance of the ignition coils.

Can you test the coils when they are installed in the car?

Because there is no spark from either bank of the engine, is it likely that both coil modules have failed?

Or, is it more likely that the supply current to both of the coil modules have failed?

Do you know how to test the current that is supplied to the coil modules?


LRT.

You can test the secondaries by measuring from one plug boot to another, use the firing order to find the leads that are 4 cylinders apart. You can test coil voltage pulses at the ECU if you have a wiring diagram to determine the correct wire colours and pin connections.

But it is far more likely your loss of spark has nothing to do with the coils. First check the fuses that are marked with "engine" type signals in the fuse boxes.

Immobiliser failure or crank angle sensor failure spring to mind. You don't get spark unless the ECU gets all the right input signals. You may need someone with diagnostic skills to drop in on you.

Hi bee utey, I have checked all the fuses and none of them have any corrosion. However, I still need to remove and disassemble the fuse box under the steering column. The earth next to the BCU is tight as is the earth points near the battery and engine earth strap. We are also going to fit a new crank position sensor and will see if that is the problem.

The only fault codes which occur are:

Fault 236 P0600 CAN - Timeout EGS/Auto Transmission CM Signal Missing.

Fault 148 P1668 Anti-Theft Alarm System BCU/BeCM Serial Link Immobiliser Signal-CAN Data Bus.

The odd thing about the P0600 fault is that our Discovery doesn't have an automatic transmission!

I wonder if an ECU from automatic transmission has been fitted, or if the ECU has been programmed incorrectly? Were different ECU's fitted for different drive systems?

See further the following links, which may be helpful for understanding the problems we are having with the Discovery II V8:

http://www.aulro.com/afvb/discovery-...on-sensor.html

http://www.aulro.com/afvb/discovery-...ion-fault.html

http://www.aulro.com/afvb/discovery-...out-fault.html

http://www.aulro.com/afvb/discovery-...-starting.html

LRT

Sadly I don't excel at electronic fault code diagnosis stuff so It doesn't mean much to me.

If you are interested I have some wiring diagrams I can email you direct, I had some scanned to jpg format. They are good at finding wire colours, relays and connectors for the engine management. Pm me your email address if you want them.

Bee utey, how do you test the coil voltage pulses at the ECU with a multimeter?

The fuel pump works, which means that the engine isn't totally immobilised.

What could be the cause of this problem, as the ignition turns on and the engine cranks?

LRT

Originally Posted by LRT

Bee utey,
1. how do you test the coil voltage pulses at the ECU with a multimeter?

2. The fuel pump works, which means that the engine isn't totally immobilised.

3. What could be the cause of this problem, as the ignition turns on and the engine cranks?

LRT

1. ECU outputs are best tested with a LED circuit tester, should be easily available from any auto shop. Multi meters aren't designed to see sharp pulses. LED testers are much faster. A more sophisticated gizmo is this one:

SXE-Probe_(VFP1000)

...which I have, its invaluable around modern cars.

2. When you say the fuel pump works, can you hear it after the starter motor stops turning, or only on the first key-on moment?

3. Car's use-by date has been passed, ECU packed up, karma, who knows? Sorry. My wife's 1993 Camry ECU packed up the other day, luckily I have a spare camry which I could swap the ECU with. Sadly you don't have that easy option as your ECU is vehicle coded. Probably a tow truck/stealer job.

Many thanks bee utey.

Thanks so much for recommending the SXE-Probe. I checked the web and it seems to be a superior trouble-shooting probe. I will try to purchase one ASAP.

The fuel pump only works for 30 seconds after turning the ignition on for the first time.

We connected a Schrader valve connector to the fuel rail test valve at the back of the manifold to test the fuel pump. When cranking the engine, a steady stream of fuel is pumped through.

What is also odd is that once the engine is running, it runs without missing or any other running problems.

LRT