Ignition Coil or Immobiliser - or something else?

Hi All,

Recently joined up after using the great wealth of knowledge on this forum for the last year or so as a guest.
Work undertaken in the last year on my 2003 Freelander TD4 includes (and probably won't be limited to):-

New turbo
New cylinder head
New drive shaft to NS (front left wheel)
Internal body repairs to rear floor pan
Starter motor overhaul/rebuild
and so on.....

Current issue I have is:
After completing the cylinder head and turbo change everything is reconnected and oiled/sealed as it should be. Problem is that it just won't start. I have been through all the threads looking for a similar set of symptoms but so far haven't found anything of use - unless it is the often cited ignition switch failing. Others have mentioned the ECU and key being out of sync, but that would suggest that the immobiliser would remain active, whereas mine appears to disable correctly.

The alarm fob unlocks the doors and the immobiliser light stops flashing. When I put the key in the ignition and turn it to the second stage all lights come on as they should. All electrics work (new battery just to be sure) I can hear the fuel pump working to prime the system (it runs for about 30-45 secs) and know that it pumps fuel to the injectors. However, when I turn the key nothing happens. The clock (telling the time) dims and that is all. The immobiliser light never flashes.

I have checked the connections under the bonnet and can turn the engine over if I connect the start directly to the battery to bypass the starter relay. However, I can spin the engine for 30secs but it still doesn't fire up.

I have checked all wiring connections and am confident they are good - eg used ammeter to check starter cables and points. I know the starter is good by itself, so clearly it isn't receiving a signal from the ignition perhaps due to the immobiliser as the wiring diagram would suggest.

Similarly, it would suggest that the glow plugs aren't being heated to ignite the fuel when spinning on the starter because of the immobiliser- or do I have this wrong?

Any thoughts on this are welcome as I know it's been heavily discussed. I have described the situation as best as possible, but please let me know if I have done something wrong or am looking in the wrong place trying to solve this problem.

Thanks

Did it work after the Starter motor overhaul/rebuild? Do you have a code reader it might give a clue. Also did you undo any earth straps or sensor cables?

Hi,

Unfortunately I don't have a code reader.

The starter was removed and checked once the rebuild of the cylinder head and turbo was complete as the car had the same symptoms prior to removing the starter to check it over.

Starter motor works fine when jumping across the terminals on the motor itself and also when jumping directly from the battery. It happily turns the engine over but doesn't fire the engine up when the ignition is turned on.

As far as I can tell all connections and sensors are back in place - I took a huge amount of pics when taking the engine and turbo apart for reference.

My only thought is that the starter solenoid has gone - but, if it has gone, would I still be able to jump it and turn the engine? The solenoid was also cleaned - it had some pitting but nothing major. When the starter was out it happily spun up when I bench tested it.

Bit miffed as it's the only thing that stopping me from using the car again, and sods law suggests that it is something ridiculously simple.

Others have (temporarily) bridged the starter relay with a switch. If you ensure power is getting to the relay, then using a switch ensures the power is getting to the starter solenoid. If the engine still doesn't turn, then presumably the solenoid is kaput. I say this as you've actually confirmed the starter is capable of turning.

Not sure why it won't run. However, I'd check the "usual" culprets of the pressure sensor wiring (replacement upgraded harness available) and the Pressure Regulator O rings in the HO Fuel Pump.

If the head has been off. Is the cam timing correct?
Otherwise it could be a simple O ring as GG said.

Hi Nodge68 & GrumpyGel,

Head has been off and timing is correct using the special tool and then I turned the engine by hand to ensure it was still aligned as per the RAVE workshop manual before closing everything up.

Having tested the voltage at the starter motor I know it's getting the full 12v at the terminal. The dimming of the clock in the car suggests that power is attempting to go somewhere, but not anywhere near the starter to trigger the solenoid.

So perhaps the fault is with the pressure sensor harness?

Not too sure about the Pressure Regulator O-rings in the fuel pump. It pumps fuel to the injectors (tested before re-assmebling the intaker manifold. Could it be it doesn't fire because, despite receving deisel, it isn't at a high enough pressure? Or would this in turn point the blame at the harness for reading/detecting the incmoming fuel? I am fairly confident the fuel pump and o-rings are good as they were replaced shortly after I bought the car a few years ago - having said that, they were replaced by the sellers 'brother-in-law who has a workshop'. So perhaps that was a slight bodge too? There have been no leaks since their work, and no leaks since attempting to run it in the last week or so, which would suggest to me that it is okay.

If the correct pressure isn't being provided at the injectors would this disable the starter relay (and ignition of the glow plugs)? Because obviously when you turn the key from stage 1 to stage 2 there is usually a delay until the 'coil' light goes out, then you go ahead and turn the key the final stage to start. My lights go out as normal but when the key is turned - nothing. This to me is the trigger for the other issues.

I will check the harness for any signs of wear and possible earthing to the engine block and get back to you.

Quick update - just spoke to a local Landrover specialist near Woking.

When I mentioned the not starting symptoms - both from inside the car, and from under the bonnet - they immediately said to re-sync the immobiliser and ECU and all should be well....... I'll give this a go as well as chekcing the other parts raised by GrumpGel and Nodge68.

Thanks for the advice and will keep you posted on what it actually turns out to be.

Starter not turning over...

When you are away from the car and it is locked with the remote, there is a LED that should blink on the dash. When you unlock and enter the car, this LED should stop blinking. When you turn the key to start the car, the LED should stay off - if it turns on solid then the security system has 'immobilised' the car.

There are various 'systems' that get immobilised if that LED is on solid. The starter motor is inhibited by disabling the starter relay (it cuts the ground curcuit) on the LV side. So if that LED is not lit, the starter (solenoid) is not immobilised and should function.

A low fuel pressure will not disable the starter motor.

Engine not running...

If that LED is on solid, then the engine ECU will be immobilised also. It is possible that the engine ECU may separately go into an immobilised state. I believe in this instance it will not power the injectors. I suppose its possible this is happening and if the LED is lit, then definitely! - but from the threads that go through this forum, I'd say unlikely. A good diagnostic device should be able to examine the engine's ECU to see if it is in an immobilised state.

If you've removed a diesel feed pipe from an injector and seen diesel pumped out of it, this doesn't really tell you a lot. Obviously if the pipe is open, there is little pressure needed to pump diesel out through it, and probably less pressure than the alternative which is all the way back to the tank possibly via a cooler and possibly via an O ring that has perished.

The alarm and LED works as it should - flashes when car is locked, and stops flashing (and goes out) when unlocked. It doesn't flash when I try to start the car.

I have ordered a diagnostic reader and will plug it in once it arrives.

With regards to pressure and the fuel feed - when the fuel feed pipe was unplugged and the ignition switched on (to prime the system) I got a constant flow of diesel. Not a fast flow, more of a trickle. It would fill a jam jar in about 30secs. Does this sound right, or is it irrelevant as it would not be under any pressure? Also if an o-ring had perished surely I would spot a diesel leak somewhere?

Mako20 said:

The alarm and LED works as it should - flashes when car is locked, and stops flashing (and goes out) when unlocked. It doesn't flash when I try to start the car.

I have ordered a diagnostic reader and will plug it in once it arrives.

With regards to pressure and the fuel feed - when the fuel feed pipe was unplugged and the ignition switched on (to prime the system) I got a constant flow of diesel. Not a fast flow, more of a trickle. It would fill a jam jar in about 30secs. Does this sound right, or is it irrelevant as it would not be under any pressure? Also if an o-ring had perished surely I would spot a diesel leak somewhere?

Click to expand...

Without the engine running the HP pump is not turning so you do not have any high pressure fuel.

The pressure regulator in the pump will allow excess fuel to drain back to the tank via return pipework. If the an O Ring is perished fuel will drain back through this route and insufficient pressure builds.

The injectors need a very high pressure on the fuel to push it rapidly through ultra small holes and create an even mist of fuel in the cylinders.

So it's a closed loop, and a faulty o-ring or HP pump simply returns the fuel to the tank?

A quick question then - prior to the starter motor turning, the system would have to read the correct pressure going to the injectors. So does the HP pump operate as part of the initialisation procedure in order for the engine to start? Or does it only operate once the engine is spinning by itself to avoid fuel starvation?

Without the engine turning there is no pressure at the injectors, it needs to turn the engine to build that pressure - therefore if it disabled the starter because there was no pressure the car would never start. Lack of fuel pressure at the injectors does not inhibit starting.

EDIT : Lack of fuel pressure at the injectors does not the starter motor.

Okay thanks for the clarification.

I'm pretty sure a lack of low pressure fuel would also not inhibit the starter from turning. It is controlled by the car's security (immobiliser) system, not the engine's ECU. There is an immobilisation 'hand shaked' between the security system and the engine's ECU to swap codes to make sure they are the same - but I'm pretty confident that that is the only thing that's swapped and no engine related data other than that code could stop the starter motor. You would see the LED light lit anyway.

I'll see what the diagnostic reader gives me when it arrives. I suspect it could be both, or simply a wire grounding butting the circuit to the starter and also to the sensors at the injectors.

Received the iCarsoft diagnostic reader over the weekend. I ran through the various menus and got some engine information - eg. throttle position, fuel pressure and so on. When I went through the 'instrument pack diagnosis' it stated a "Fault in communication with vehicle ECU." It then asked to confirm whether it had an ECU or not.

I'm guessing that this means that when the immobiliser is not connecting/talking with the ECU and therefore won't allow a reading and also is why the car won't start. Does this sound right?

Also bought a new solenoid kit for the starter which I will fit this afternoon. Pretty sure that the starter is fine after the work I did on it previously, but want to completely rule it out as the cause. Afterall less than an hours' work and £10 for the kit isn't too much hassle/cost to put my mind at rest.

If you have any further ideas please let me know.