R129 Door Lock LED Flashing - related to non-start?

[Ian Wardleworth]

My 1996 R129 320 refuses to start and the only clue to why is the red LED on the driver's door lock flashes at a constant 3 second intervals. Anybody any idea what is going on and what I can do to sort this out?
Any advice most welcome - the car was involved in a very minor shunt last January but all was fixed including (allegedly) resetting the immobiliser.
Thanks in advance!

 

[star]

Yes related, replace key batteries first then try.

 

[Ian Wardleworth]

Thanks you for that sensible idea - I replaced the batteries but sadly still no go. I have since found out that the red diode flash is normal.

 

[star]

Red flashing is for locking
Green for opening
Both for key battery low or Imobiliser still locked, I think.

 

[davidsl500]

I seem to remember my drivers door handle would flash at a regular interval after locking the car using the remote key fob. I thought that was to show that the car was locked and armed.? Yes it would flash red quicker on initial locking then settle down to the regular slow flash.

So if you lock the car, does it flash red quickly on the door handle and if you then unlock the car, does it flash green and unlock or carry on with the regular red?

The other question : when you say it won't start, does the starter turn the engine over normally or do you get nothing when turning the ignition key?

 

[Ian Wardleworth]

The other question : when you say it won't start, does the starter turn the engine over normally or do you get nothing when turning the ignition key?

The starter turns over the engine but it doesn't fire. I think I can hear the fuel pump run when I first turn on the ignition but not always. I have tried re-synching the keys with the ignition switch which I had to do some time ago but this time that made no difference. I was wondering about the fuel pump relay but I'm not sure where it is located other than under the bonnet somewhere. I also know that you can bypass the relay but no idea how. A little knowledge can be dangerous when mucking about with pressurised fuel systems so there is a limit to my willingness to go too far with this.

 

[Ian Wardleworth]

Red flashing is for locking
Green for opening
Both for key battery low or Imobiliser still locked, I think.

Thanks Star - as above the key fob batteries are all good.

 

[star]

Thanks Star - as above the key fob batteries are all good.

Are they new? Had a few instances where the car locking works but the immobiliser isn’t switched off due to key battery signal being low.

 

[Ian Wardleworth]

Are they new? Had a few instances where the car locking works but the immobiliser isn’t switched off due to key battery signal being low.

New Duracells out of the box. I should have a further new set later today just in case.

 

[Ian Wardleworth]

I seem to remember my drivers door handle would flash at a regular interval after locking the car using the remote key fob. I thought that was to show that the car was locked and armed.? Yes it would flash red quicker on initial locking then settle down to the regular slow flash.

So if you lock the car, does it flash red quickly on the door handle and if you then unlock the car, does it flash green and unlock or carry on with the regular red?

Just been out to check this and it is as you describe. I think this must mean it is not central locking/immobilser related.
I have HomeStaRT cover for this car so might have to give it a go, despite worries about the level of knowledge about a car nearly 30 years old from a breakdown man. Previous experience has not been good - not with the R129 I would add!

 

[davidsl500]

One of the "clutching at straws" things you can try; I read a long while back that a cycle of unlocking and re-locking the car 10 times in succession would reset the immobiliser. This may be rubbish but it's worth a go whilst other ideas are forth coming..

The fuel pump relay, from recollection, is above the battery in the boot behind the panel. There's a diagram of the simple relay layout so it's easy to bypass to run continually.. Its green in colour and has a 30A blade fuse. If you pull the relay, you need a wire capable of running 30A to plug in the relay socket between pin 30 and 87 you don't need to re-plug the relay back in. A bit of 2.5mm twin and earth cable would do

 

[Ian Wardleworth]

One of the "clutching at straws" things you can try; I read a long while back that a cycle of unlocking and re-locking the car 10 times in succession would reset the immobiliser. This may be rubbish but it's worth a go whilst other ideas are forth coming..

The fuel pump relay, from recollection, is above the battery in the boot behind the panel. There's a diagram of the simple relay layout so it's easy to bypass to run continually.. Its green in colour and has a 30A blade fuse. If you pull the relay, you need a wire capable of running 30A to plug in the relay socket between pin 30 and 87 you don't need to re-plug the relay back in. A bit of 2.5mm twin and earth cable would do

Thanks David - I should be able to try both those things this afternoon and will get back to you.

 

[Ian Wardleworth]

On my R129 the green relay in the boot Pt No 00 15 42 96 19 is an overload protection relay as well as being sold as a Multipurpose Relay and Fuel Pump Relay. Now what do I believe?
This is what it looks like

 

[davidsl500]

It seems to be listed for both as I think the design is pretty standard.

If you have a multimeter you could check for continuity between the injection pump and relay socket to ascertain its the right one. Assuming you haven't got a meter, leave the relay out, get someone to switch on the ignition whilst you listen at the rear for the pump. You could then replug the relay in and see if you get a noise from the pump, if not try bridging 30 and 87 in the relay socket and see if the pump kicks in.

One other thing to try ; spray loads of easy start into the air intake and see whether it fires up - which will at least verify the ignition side is working okay.