Another non starter .... sigh...

Someone please help?? I'm at my wits end with this now...

1995 4.0 ltr auto. - immobilised.

Story....
Wouldn't start one morning and was diagnosed with bad crank senseor as it would turn over but not fire. The rev counter read zero too. So put another sensor in (2nd hand) and tried it. No crank this time.

Now the immobiliser won't go off. The 'check engine' light goes out and the red P light comes on.

Have checked and checked everything I can think of..
ECU is dry.
Security module in boot is dry.
Fuses all good.
Took ignition barrel out and all seems good.
Checked connectors behind headlamp
Ignition relay is not live

Now suspicion has centered on the alarm system (immobiliser?) as under the bonnet, the relay for the 'alarm sounder and AC clutch' is permanently 'live'. It clicks when you push it in and out.
Have disconnected the ignition switch at the multi plug and the relay mentioned above is still live.
Removing the appropriate fuse in the right hand fuse box kills the relay. Put it back and it clicks.

Now my thinking is that the alarm system is permanently stuck on thereby immobilising the car.

Now more history...
Car came with no fobs, but that didnt matter as we just used the key.
Then the central locking started operating only every SECOND time. It would lock or open once, then next time only the drivers door would operate mechanically NOT the solenoid. Again not a huge issue, just irritating.

Then.. the ignition would only operate every second time! Turn it back and try again and it would work! Again irritating but not a show stopper.

Now it is dead...

It just seems the alarm is stuck on and won't switch off! (By the way the sounder died some time ago. So it makes no noise.)

Is there some 'magic' way of disconnecting the effin' thing?
Or am I looking at replacing the whole system? (Barrel, switch, ECU, Security module etc.)

Is it possible the excitor coil is not being powered up and not reading the key?
If so how do I check this?

I have this feeling that it is some really stupid little thing causing this and I can't find it!!

Please help someone.. otherwise I will set fire to the damn thing....

 

No ideas anyone...

 

Do you have tools for electrical testing?

You didn't say what tests you have done on the battery. Is it known good and fully charged?

Have you checked the +ve terminals on the bulkhead and the various earth points around the engine bay?

You really need to take a structured approach using the wiring diagrams. You say that the Ignition relay is not Live - do you mean the ECU controlled Relay on right side behind headlights? Do you mean it doesn't have a Live feed or it isn't being switched Live?

If the relay is not Live, then you need check what you have on each pin on the socket and then trace the missing signal back to where it should come from.

So a quick look at the wiring diagrams shows for the ECU Controlled Relay

Brown/Yellow - +ve feed from Fuse 11 RH Engine Bay
Brown/Orange - +ve feed from Fuse 5 RH Engine Bay
Blue/Light Green - Output when switched
Brown Purple - Earth switched by ECU

Check these out and let us know.

 

Hi,
Judging by the complicated description of lot of strange electrical issues, I would check all electrical grounds. As you say, usually complicated problems boil down to simple solutions.
Good luck,
Jorge

 

Hi guys,

Brendan...

I have a friend who is an auto electrician who has been helping.
When I say teh relay is not 'live'. I mean it is not permanently live. Apparently a common fault is that it remains live. This one isn't.
The 'live' relay is the one for the alarm sounder circuit. It stays live ALL THE TIME. Even with the ignition switch disconnected. The only way to kill it is to remove the relevant fuse.

It just seems to be that the alarm is constantly 'sounding' (although there is no noise because it has never worked) and I can't get it to shut down.

It's driving me mad..!!

 

I don't see a Sounder relay in the wiring manual. Where is the relay you are referring to as permanently live?

From the history you have given I would be focusing on that Security/Locking module and try some tests on it for inputs and outputs. There may be justification in just buying a used one of ebay - they are relatively cheap. The module is not paired with the ECU or other components afaik so can be replaced in isolation.

Here is a link to download the factory security manual that may help as it has much more info and test procedures for the security system than the standard Electrical Guide.

https://www.dropbox.com/s/nklhl2sbvh...URITY.pdf?dl=0

 

I think the Security & Locking Control Module (SLCM) in a UK spec car is configured to the transponder chip in the ignition key and requires dealer level software for set up. There is a serial communication acknowledgement that the key is correct between the SLCM and ECU on turning on the ignition when the key transponer chip is read?

 

Me again...

Slightly further forward now.
Have found the ecu water damaged. The black plug was all corroded and green.
Have cleaned it, replaced broken pin, dried it out and ready to reconnect.
Not feeling hopeful but you never know.

Now in addition the ignition barrel had collapsed! Won't turn fully to engage anything. But removing the electrical switch allows me to operate it with a screwdriver. ( obviously with the key in the excitor ring)
But even with the switch disconnected and the ecu removed...the bloody alarm relay is STILL live!

 

IT LIVES!

SHE'S ALIVE!!!

The water damaged ecu plugs and as I discovered a 'butchered' harness in the boot at the hinge was causing the problems.

Thanks for everyone's help.

 

Congrats, sounds like the problem I had with mine posted in an earlier thread. Mine were frayed at the beggining of the plastic cover that hides the wires. Is that around where yours was butchered at? What did you do to fix it? Patched up the wires or ran new ones?