Flashing immobiliser/engine light

My 2003 Jimny manual has started doing a thing. Intermittently it will not start due to the immobiliser light and engine light flashing so I remove the key and put it back in and starts fine. Then it will drive for a minute or so then die with the immobiliser light flashing and engine light then just fires up again and drives normal. It will then drive normally thereafter. Doesn’t do this ALL the time but it’s getting more often these days. One start up it was doing a full light show and the speedometer shot round to max every time it was malfunctioning. It’s difficult to get a video but I’ve managed to get one today when it started fine then did its performance 30 secs into the journey. It kinda winds down and dies then fires up again. Is it just a case of needing a new battery? 

A flat battery can cause a lot of intermittent electrical faults, so it's definately worth putting the battery on charge to see if that fixes the problem. If it does a new battery is a lot less money than fixing the immobiliser or ECU.

The bad news is a flashing immobiliser light usually means that there is a fault with either the immobiliser, the key or the ECU. There are a few checks/tests you could make see the following wiki entry

www.bigjimny.com/mediawiki/index.php/Key...g_transmitter,_alarm

Have you got an OBD code reader, you should get a code logged if the ECU has seen a fault with the immobiliser.

Do you have two keys, if so try the other key, it has a chip and small transmitter in it.

It could be worth a full reset once you have a charged battery. Disconnect the battery for 30 seconds or so, reconnect, then lock the car. Leave it locked for a few minutes then unlock the car, re-check for the immobiliser flashing.

Robin

Mine had problems with this earlier when the dash cluster was fried. Yes I let the smoke out of the Electronics.
The ECU has the code for the chip in your key.
When the chip is in the ignition or close to the ring antenna the signal is amplified in the immobilizer unit and sent to check with the ECU.
I bought a immo chip programmer from ebay so I could code the key back in the ECU when it lost it.
After changing the dash cluster it has not happened more.

The issue seems to have resolved now the weather is significantly less wet. *touch wood* I’ve not had it do it again since it’s stopped raining 24/7

This might suggest water ingress to a connector between the ECU and the steering column? It might be worth a look under the dash to see if there is a leak.

Or possibly another connector/cable in the system somewhere.

Damp weather can also cause leakage of the HT system (coils and leads) and this can increase current flow. It is also known to cause leakage in the alternator and you might find your Jimny hasn't been charging correctly. Have you also been getting belt slip/squeal?

Did you try charging your battery?

Robin

Yes I have been getting fan belt squeal occasionally but only when all wipers/lights/heaters/stereo is on short journeys

I haven’t tried charging the battery yet as I only have a jumpstarter pack and not a charger