Immobiliser mischief?
 

I bought my Rover 75 CDT in July 2006 and, after some initial problems with injectors, it has been a delight. Three times in that period, though, it has completely failed to start, and the worst and most serious instance was a couple of days ago. When I say failed to start, I mean it turned over OK, but nothing more, not so much as a cough. Normally it starts straight away without a problem.

Now, each time this complete non-starting has occurred, I believe I have, immediately prior to the non-start, done something slightly different from normal as regards unlocking the car - maybe accidentally re-locking it and then immediately unlocking it again, or something like that. Each time, the car has eventually just sprung back into life as if nothing had happened.

The other day, I had been for a short walk, then got back into my car and felt sleepy, so, deciding a short snooze might be in order, I pressed the button to lock all the doors. I then realised I probably wouldn't be able to sleep so decided to head off anyway and attempted to start the car, but no joy. I immediately thought "Ah, it's that old immobiliser mischief again", so did every permutation of locking, unlocking, getting in and out, etc, I could think of, but it still wouldn't start. I thought it must be something different this time, so called out the recovery people. Anyway, the guy couldn't work out what the problem was and could only determine that no power was getting to the under bonnet fuel pump (certainly I wasn't hearing the normal burring noise before starting). I took a look to see if the ECU was wet but the plenum was dry as a bone. Anyway, just after I'd put the ECU back into place, the recovery guy tried the ignition on and off three times in rapid succession, and bingo, it sprang back into life as if nothing had happened.

Now, it strikes me that this is likely some kind of immobiliser quirk, some bug to do with some sequence of actions which causes it to misbehave (unless there is some other explanation which someone can think of). Has anyone else come across such an immobilisation problem? And is there some way of effectively resetting the immobiliser, some sequence of key fob presses perhaps, that tells it to pull itself together and stop being silly?

The immobiliser inhibits the starter motor so if the engine is turning over, it's not that. (If you have the message centre, it tells you when the engine is disabled). If there is no power to the fuel pumps it could be the fuel pump relay.

Most common Problem of Non Starting is CAM Sensor.

i am having this problem now, twyce its happened. starter motor turns, wuring from the rear lasts about 3/4 seconds(may be sender unit ). then after 20 od attempts starts up...runs ok when started no problems there.
so to be dim.....whats this sensor and where is it?



:xmas-smiley-019:happy christmas too:xmas-smiley-009:

Immobilser and locking aren't actually linked (other than they both live inside the key head).

The alarm / locking transmits when you press they fob. The immobilser has a transponder chip which only transmits when it's in the ignition lock. The ECUs that receive the signals are different too.

So sorry, the theory doesn't stack up, and as pointed out an immo lockout also prevents cranking.

So cam sensor, fuel pumps, or glow plugs. If it's OK when cold, but always fails with a hot engine, I'd plump for cam sensor too.

The odd thing is that 99.9% of the time the car starts without a problem. As I said, this problem has occurred just three times in the 18 months I've owned the car. In each case I've done something unusual with the unlocking immediately prior to attempting to start, hence my suspicion that it was something related. Surely if I had a faulty cam sensor or the like, I'd get regular problems starting, wouldn't I? There is normally no problem whatsoever starting.

As I mentioned, there was no power to the fuel pumps, which would appear to rule them out. How would a problem with glowplugs manifest itself?

Also, how do I check out the fuel pump relay?

Strikes again!
 

Hmm, the mysterious complete non-starting has occurred again. I just had an MOT test done (which the car passed, to my relief), and the mechanic could not start the car to drive it away from the test bay. Same again, turns over without so much as a cough. He said he had initially locked the car, then immediately unlocked it again before attempting to drive away (once again a slightly unusual sequence of actions).

I was completely unable to start it, despite numerous locks, unlocks, etc. Then I opened the bonnet, unplugged the RoverRon Synergy unit, plugged it back in again but turned it off, and then it started straight away. So, I turned off the engine and turned the Synergy back on and tried again. Once again it started fine. What might this point to? I doubt it's a fault with the Synergy because on the previous occasions when the problem has occurred, I haven't done what I did this time. It seems to me in some way ECU related, but I can't think how.

Incidentally, the smoke reading in the MOT test was negligible, despite the Synergy being on its highest setting (10), which I'm very pleased with. The engine runs wonderfully and certainly doesn't show its 166,000 miles.

Do you have a spare key and have you tried it ??

I do have a spare key. I haven't had it with me when the non-starting problem has occurred. Perhaps I'll take to carrying it with me. Why would the spare key help? You reckon it could be some key fob related issue?

Interesting.

I still can't see how the locking and immobilser are related. It's not any sort of functional relationship, so it must be something odd like earthing or power supply if it is related at all.

Honestly, there is really no working involvement with immobilser and locking. And the fact that the car turns over backs up that the immo is OK, it wouldn't even turn over if it was unhappy. I'll photograph the inside of my spare key to show you the two unrelated parts, if you like.

There is a pattern, but try to avoid falling into the trap of fitting the symptoms to what you think it is. Take a step back, and try to see what other clues there might be.

Glow plugs: if these aren't working typically it would be cold starting that's a problem. Failure to start after the MOT probably rules this out.

immobiliser mischief
 

I am having exacly the same problem, doen't start randomly. Today started fine, travelled 50 miles , restarted 3 times, travelled 50 miles, stopped for lunch, refused to start.
I shall be trying again after sending this.
Is it possible to disengage the immobiliser?

Immobiliser, non starting
 

After a 2 hour wait the engine has started, any views

As mentioned before Cam Sensor most likely the culprit when there is a hot start problem.

Quick test if car doesnt start when hot take off the cam sensor, place in fridge for 10 mins, and refit. If the car then starts you need a new sensor.

How about the under bonnet diesel pump.........??? Mine did this the other day, gentle "adjustment " with a hammer and it's been fine (Touch Wood)

No. It would be a bit pointless if you could overcome it without major trauma.

Is the transponder in the key active or passive?
 

My 75 Tourer has just started playing me up with the immobiliser. What triggers the transponder chip when it is in the ignition lock? Is this a passive transponder or does it rely on a battery in the key? Is there a way of completely bypassing the immobiliser? This is now happening with both of my keys. HELP!!!!! :(

In what way is your car playing up? A list of the symptoms will help diagnose the problem as it may not be immoboliser related - for example other electrical gremlins can produce strange results.

Hi. The transponder doesn't rely on the battery. The coil around the ignition lock transmits a signal to the chip. The chip powers itself from this signal, and modulates the signal to talk to the immobiliser. The immobiliser also modulates the signal to talk to the chip. It's triggered as you turn the key from off, to accessory.

The battery is for the remote control: in the same box as the transponder, but not connected to it. The transponder has nothing to connect it to anything. You could take the battery out, and the transponder will still work. In fact early cars were meant to have one normal key an one key with only a transponder. Don't know whether this ever happened, but it would explain why so many early cars have only one key.

As I said earlier, the immobiliser would be a little pointless if it could be overcome without a good deal of effort: whoever wanted to steal your car would simply switch off the immobilser and drive your car away.

Diesel Intermittent Strating problems
 

Like many of us I have suffered the frustration, although rarely, of the starting problem. Usually resolves itself after being left alone for periods of time but still left me baffled. Tonight it happened again. RAC man turned up and immediately stated that he had dealt with this problem before. Popped the bonnet and tapped the top of the fuel pump. I turned the key and the old girl fired up immediately.
I have had my 75 since new (6 years) and 65,000 miles later I still believe it is one of the finest cars on the road. Hope this helps.

:welcome: to the Club Paul. :)

Thanks for the informative first post. As you have discovered - a sticky/failing underbonnet pump can cause starting issues. A quick tap unsticks it. Other fuel-related issues include the other fuel pump in-tank (where fitted) and the fuel filter which can come unscrewed (this is a simple fix with £2 spare part fitment to prevent repeat unscrewing).

Hope you enjoy your stay here - plenty to read up on and do if you haven't already seen. :)

Same problem
 

I have had my car for almost two years and have had absolutely no problem, but twice over this festive season, I have gone to my car and it has not started.

However, thinking about it, on both occasions, I went to my car, put the key in the ignition and started it, then remembered I needed to do something, so turned off the car, did what I needed to do and and quickly returned to the car. It then would not start.

There was no engine action at all (all ignition lights came on).

On the first occasion, we left it overnight and it started normally in the morning. Today, I could not get it to start. My husband left it for a while and then it started, then it wouldn't, then it started.

I am really concerned that I am losing confidence in my car. I want to be sure that when I go to it, it will start.

Any help would be really appreciated

Thank you
Lynne

Hi Lynne and welcome to the club.

So that a more specific reply can be given can you let us know what model you have ?? Diesel ?? Petrol ??
If Petrol what engine - 1.8 ? 2.00 V6 ?? 2.5 V6.
Automatic or manual ? How old is the car and mileage.

EAch model can have different likely causes of non starting.

However one thing common to all is the battery. If the car is over six years old and is on the original battery then its on borrowed time.

Did you notice if the headlights flashed when you tried to start the car and failed ?? The cars computer (ECU) checks the battery power level every time before starting the car. If there is not enough in the battery the ECU will not allow the starting proceedure to continue and to let you know this will get the headlights to flash at least 3 times.

If this is the case and the battery is over six years old then it could be new battery time. If the battery is fairly new then it could be that you do a lot of short journies which has not given the battery enough time to recharge properly. Think it takes about 5 to 10 miles of running to replace the energy of ONE COLD start. A decent long run (once the car is running) or useing a battery charger every now and again might cure things.

HTH

Thank you so much for replying

I have a Rover 75 1.8 petrol car.

I did not see any flashing of headlights, although it was daylight on the two occasions it failed, so may not have noticed.

Also, as previously mentioned, on both occasions, the car did start with no problem, then after stopping the engine for a short while (and removing the key from the ignition), it refused the start again because of the immobiliser.

As far as travelling is concerned, I travel long distances (all over the country) as part of my work, so there is no problem with that.

The car is six years old, so not sure if the battery is the same age as the car or not. It certainly does not seem to have been a problem, and has started every single time since I bought it - until recently. The car has done 60,000 miles (it had 33,000 miles when I bought it) and is manual.

Thank you very much
Lynne

Urban Myth I'm afraid.

The car has lots of computers, and the one that drives the headlights (light switch module) has nothing to do with starting the car (EWS and Engine ECU).

Besides which, it's almost impossible to measure the battery condition by voltage alone. The voltage profile of a battery from fully charged to low, and the effect of loads and temperature on that battery make it way too complex.

The effect you see is the system trying to bring in the starter solenoid. This current draw is enough to drop the voltage far enough to reset the cars systems, which includes the light switch module which causes the lights to flash, and the EWS (immobiliser) which means the starter solenoid is not actually pulled in.

I am still thinking battery just about to fail. The batteries on both my 75's failed at 6years 2 months.

Your first start is OK but depletes the battery so much that a second start is prevented by the ECU.

Really cold weather wont help either.

Would suggest getting the battery checked out first.

Hi Lynne
I work with your husband at Dunlop. As David says it could be the Battery on the way out . Mine Failed last winter at 5 years old .If you have never had the Plenum drain checked for water ingress I would check this because water will kill your ECU. I am off shift this Saturday and Sunday if you would like me to check your Plenum drains. Just Pm me and i will give you my address in Habrough.

Think I have found the answer
 

Had the same problem last night - car wouldn't start at al - and this time I was in Tesco car park at 10 pm. Called the AA, who had it going within about three minutes. He said it is a common problem with Rovers and Peugeots. He said that it is a bad connection on the starter motor. He took off the connection, cleaned it, sprayed it with WD40 and it started. He said I should have no more problems.

Hope it is the naswer to everyone else's 'immobiliser' problem

Thank you to all who replied. I really appreciate it

Lynne

intermittent starting problems
 

I spent hundreds of pounds, and the car spent weeks in a series of garages trying to find out why it started fine sometimes, and other times all you got when you turned the key was a 'click'. Eventually it was my mate who found the problem, it was a loose battery post. The connections to the battery were fine, but you could shoogle (move back and forwards) one of the posts.

The phantom non-starter has struck me again too! Last night (getting a bit frosty) the alarm went off. I went and reset it, but it blipped as if there was a door open. I closed all of the coors and the boot, and it reset without a hitch. 2 minutes later the alarm went again and I was unable to reset it as it still thought somewhere was open. I had to leave the car unlocked because I was unabel to start the car! It turned over, but wouldnt start (no coughing or spluttering). I left it, and this morning I have the same problem.

This occurred last year and I removed the bonnet sensor switch as it wasnt working, and I have sealed the ends of the cables so that the circuit cannot complete, so I know it isnt the bonnet. I cannot see why it will not start, but again this happened last year, and as soon as I removed the bonnet switch and reset the alarm (no blip) the car started fine.

Any advice on how I can fix this? Im getting to the end of my tether with this car and I think it is going to have to go once I have sorted this out. Head gasket, stereo, cat converter and exhaust have al had to be replaced since I bought it in November last year, and now this!!!

(its a 75 1.8 petrol turbo, 53 plate)

bump,

any help at all, this thing is driving me nuts!

Give Messenger a call, and get him to put it on his T4 (testbook) as there should be some fault codes stored.

Check the wiring going into the inertia switch!. Easiest way is to remove the glovebox to get right into the wiring (4 torx screws at top, 3 hidden under mat in glovebox). Press the rubber button on top and you should feel a small straight gap, thats where the switch would pop up!. Now make sure the wiring connector is TIGHT.
I had the same symptoms and this was the culprit.....like you say, drives you nuts!