Temperamental immobiliser

[woodlandsale]

After driving for a while, and stopping (at the take-away for example), I have several times found that pressing the remote keyfob button enables the fuel pump, but the starter doesn't engage. Faffing with the button to set and then unlock the central locking eventually results in the starter working, but it's unpredictable. By then the food might be getting cold! The key fobs were new a year or so ago, so this problem doesn't seem related fob failure as such.
Is this a common fault, with a known cause or cure? I would happily do without the immobiliser altogether, and fit a battery cut-off switch or something similar for security. Is it possible to eliminate the immobiliser function and leave the central locking functional?
Any comments or suggestions gratefully received.

[QBee]

If your alarm/immobiliser has never been changed, then you are describing the classic hot start problem. I had it, and whenever it struck used to have to sit for 15-20 minutes for everything to cool down enough for the car to start. It even happened on day one of ownership.

Eventually I had so many problems with that and the alarm too (indicators coming on one side only, on, not flashing, all night, flat battery etc) that I talked to Carl Baker and spent my £550 having a complete new Meta system installed. Never had a starting problem since.

One other thought for you - if your battery is ancient it may be worth replacing it, as being low on amps will show itself most when everything is hot.

There are loads of threads on here about the various causes of this issue -

TVR wiring the immobiliser incorrectly,
the immobiliser eventually failing,
the hot start mod,
the wiring from battery to starter,
the life of the solenoid,
good earths etc

Worth using the search on "hot start issue"

[Belle427]

You could link out the Immobiliser as you suggest, any Autospark or alarm specialist could do this for you.
Tricky to do yourself without electrical experience but usually its as simple as identifying, cutting 2 wires related to the circuit and joining them together.
The locking part of the alarm will still function.

[woodlandsale]

Thanks guys- very interesting. Have to say I'm not convinced about the hot start problem, unless this is something that can happen sporadically. Mostly my car will start easily when hot. Bypassing the immob might well be my choice, I think. If done carefully I guess it could be reversed, which would be useful when I come to sell. I might also find that I actually do have a hot start problem anyway, so then it will be time to pursue the solutions you mention.

[Richard 858]

If you fancy having a go at a hot start bypass yourself (and if I can do it, it must be straight forward!) ChimpOnGas has a nice & easy guide to it. The most time consuming part is undoing the 2 nuts on the left hand side of the upper dash.

[ChimpOnGas]

woodlandsale said:

Bypassing the immob might well be my choice, I think. If done carefully I guess it could be reversed.

Exactly, my instructions are careful to ensure you can easily reverse the bypass, if (for some unfathomable reason) you ever decide bringing the failing immobiliser back into the starter circuit is a good idea????

Richard 858 said:

If you fancy having a go at a hot start bypass yourself ChimpOnGas has a nice & easy guide to it. The most time consuming part is undoing the 2 nuts on the left hand side of the upper dash.

^^THIS^^

Always happy to share, just send me a PM and I'll email you straight back with some clear & easy to follow instructions with photos

In my experience (and that of loads of other Chim & Griff owners), an immobiliser bypass is a highly effective solution that addresses the true source of the hot start problem. The car remains secure because you're only bypassing the immobiliser on the starter circuit, post bypass it'll still control the live feed to the ECU.

Following the bypass you'll be able to crank the car on the starter without disengaging the immobiliser but the engine still won't start, it's not until you press your immobiliser fob that the ECU will become live. You'll hear this as the ECU runs the fuel pump so the buzzing pump sound serves as your audible indication the car is ready to be started.

But I'd like to be 100% clear here.... what the bypass can't do is fix a failing starter motor, neither can it add the relay to the starter circuit that for some reason TVR thought unnecessary???

Here's a simple diagram to show you how to add/wire in that missing relay:



Assuming your starter motor is healthy it's certainly a good idea to add in the missing relay as part of your bypass and complete health check of the two separate starter circuits (high amp & low amp). While its true some have had success just adding the missing relay without completing the bypass (which is effectively all the ModWise hot start kit is), be aware while the David Beer's kit may help in the short term it can not repair any existing immobiliser internal damage which is extremely common on these cars.

The internal immobiliser damage was a result of TVR wiring the low amp ECU circuit through the high amp immobiliser circuit and the higher amp starter solenoid circuit through the low amp immobiliser circuit. Essentially TVR wired the immobiliser back to front, the little relay embedded inside the immobiliser that TVR chose to use for the starter solenoid circuit was simply not man enough for the job, consequently it had a rather short life.

By all means fit the hot start kit from ModWise but please be aware without an immobiliser bypass or the installation a new correctly wired security system the dreaded hot start problem may very well come back to haunt you in the future, and at a very inconvenient moment.

Finally it's also worth replacing the feeble and very light gauge starter cable used by TVR. Use a new heavier gauge cable from the positive battery terminal to the starter motor then run a length of the same heavier cable from one of the stater motor mounting bolts directly back to the negative terminal on the battery thus completing your upgraded high amp live feed circuit with a really solid earth return.

It's like this....

1. Check your starter motor is in good health first, if not replace it

2. Bypass the immobiliser on the troublesome starter circuit only

3. Add the relay to the starter circuit that TVR wrongly deemed unnecessary (see above simple diagram)

4. Upgrade your starter cable and add a high amp earth return in the same heavier gauge cable

http://www.pistonheads.com/gassing/topic.asp?t=110...

The above four steps are straightforward to complete and the parts aren't hugely expensive, absolutely no question what you'll end up with is an infinitely more dependable and reliably starting Chimaera or Griffith

Hope this helps?

Dave.

[bsdnazz]

This could well be an immobiliser fault.

The original immobiliser contains two relays - one for the fuel pump and one for the starter motor solenoid. The starter motor solenoid relay can fail.

I had this problem some years ago and confirmed the problem by slapping the underside of the passenger dash while holding the ignition key in the start position. When the ignition key is in the start position the starter motor solenoid relay in the immobiliser should close and enable the solenoid to move and engage the starter motor. The failed relay does not always do this and slapping the dash is enough to 'encourage' the relay.

Once this was confirmed (several slaps on several occasions) I had the immobiliser replaced and have not had a problem since.

[eric450]

Probably a daft question but ....
As the Chim was in production for 10 years, was there not a time when TVR noticed this error and fixed it?
OK, I said it was a daft question.

[ou sont les biscuits]

eric450 said:

Probably a daft question but ....
As the Chim was in production for 10 years, was there not a time when TVR noticed this error and fixed it?
OK, I said it was a daft question.

From what I've read, TVR were told they were wiring the relays the wrong way round by Meta right from the moment they started fitting the immobiliser. Why they chose to ignore advice from the manufacturers is a complete mystery.

That said, it's an easy DIY fix to swap out the old Meta immobiliser and alarm system to a later M36T2/HPA system with the relays connected the right way round, and which, apart from sorting out the hot start issue, has the advantages of being able to switch off the microwave sensors when you lock the car (thus removing one source of battery drain) and a remote operated boot release. That last feature was for me personally worth the £300 quid the new bits cost to buy. It's a boon at petrol stations, or when you just want to get something out the boot, etc etc.

[woodlandsale]

My starter seems pretty healthy- cranks quickly, albeit briefly as the engine fires almost instantly, since I had the injectors cleaned and a couple of other things.
Chimpongas, I've e-mailed you separately, having had your instructions passed on by another mate, so I'm going to give them a try.
Thanks to everyone for contributing.

[Plan B]

My starter occasionally refuses to activate despite having a new meta immob and new relays and new starter installed. I find that disconnecting/reconnecting the battery returns normal service. No idea whether it's due to rebooting the meta or the 14CUX all I know is it just works in my use case.

[Plan B]

My starter occasionally refuses to activate despite having a new meta immob and new relays and new starter installed. I find that disconnecting/reconnecting the battery returns normal service. No idea whether it's due to rebooting the meta or the 14CUX all I know is it just works in my use case.