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Discussion Starter · #1 ·
I have a 2005 Corsa C 1.2 Twinport (Z12XEP) that won't start whilst displaying a flashing spanner icon.

I'm hoping someone can suggest steps to narrow down the fault. I have access to v1.39 of OP-COM for diagnostic info.

Some observations:
  • The car won't start when I have a flashing spanner icon
  • I can start the car if I do ANY one of the following (spanner icon stops flashing)
    • Disconnect/Reconnect battery negative terminal
    • Disconnect/Reconnect Fuse F3 (Instrument Panel inc. immobilliser power)
    • Disconnect/Reconnect immobiliser connector
  • If I turn the car off and wait a little the flashing spanner returns (and car won't start until I do one of the above)
  • OP-COM reports fault code P1612 - Immobiliser No or Wrong Signal
  • When the spanner is flashing I cannot access the Engine(ECU) or Immobiliser clusters using OP-COM (non responsive)
  • If I get rid of the flashing spanner icon (as above) I can access the OP-COM Engine and Immobiliser pages.
I don't know if this is an immobiliser fault or ECU fault. Should the ECU be accessible with OP-COM if the immobilliser is not responsive?

Would appreciate any suggestions as to what further tests or op-com info would narrow down the problem?

Thank you
 

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I imagine that you have cleaned the immobilizer connector just in case, if you have other llsve try another one, if it does not remove the watch box and tighten the connector, which many tend to connect badly over time, it seems that you have a bad connection in some connector
 

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Discussion Starter · #3 ·
I've done a quick clean of the connector but nothing thorough. The problem returns consistently even though I've unplugged and plugged in the immobiliser connection many times to start the car so I'm inclined to think it's not the fault of that connector.

What's a llsve?

By 'watch box' do you mean the speedo dials (instrument panel)?
 

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As you can not connect to the ECU when the fault is present I would be looking at the ECU to body plug. If this has oil in it chances are you ECU is faulty, The ECU to engine plug will have more oil in if this is the case.

As Jewels said and I think you are right that he means the plug on the back of the speedo. There was a recall to make the plug on a loose lead and not fixed to the dash panel behind the speedo so you push the dials back on to the plug but now you would plug the dials in then fit them to the dash. These plugs are well known for causing immobilizer faults on the Corsa C.
 

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Discussion Starter · #5 · (Edited)
OK, I'll take off the instrument panel and check the connector then as it sounds like it might be the root cause.

I’ve taken off the ECU to Body plug a few times to check for 12v, GND and continuity from the immobiliser connector to the ECU connector. The tests passed but I must admit I didn’t pay attention to whether there was any ingress of oil when I had the connector off so I will revisit that too

I assumed that the ECU non-response in OP-COM was because the immobiliser might wake up the ECU after a successful immobiliser handshake. Is this not how it works? Is there any info online on the ECU and Immobilser startup process?

I notice that the ECU to Engine plug has a plastic jacket covering the connector's metal lever. How is this jacket removed? Also, if I did have to remove the ECU at some point is there enough space to get a screwdriver on the 4 screws of the ECU? At first glance it looks like a very tight space for accessing the bottom 2 screws without having to remove other parts?
 

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You can remove the ECU without removing other parts first but it is tight. Be sure you re attach the earth cable to the ECU body when refitting.
The plugs un clip to get ti the back of the cables then a purpleish coloured slide comes out if you want to remove any pins?

The ECU has a constant power feed, red wire. Switched power feed, black wires.
Power from the key is sent to the ECU via a relay and fuse then a signal comes back out of the ECU to trigger the ignition and fuel pump relays, for this to happen the immobilizer does as you say require "a hand shake" with the transponder ring and key chip. I have had a key loose it's program some how and not always start the car but the spare does. This is on our Meriva A which is based on the Corsa C. It was just an intermittent fault so we have carried on with it as it is at the moment with the spare.
 

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Discussion Starter · #7 ·
That's great info. I will also trace the relay and fuse to see if the unresponsive ECU is just because the relay is not firing.

Thanks
 

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It's 2 of the yellow relays in the main fuse box and the 2 purple ones at the front of the box are the ignition/engine electrical power and fuel pump.
 

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Discussion Starter · #9 ·
I've just taken the instrument panel off with the intention of checking the connector for any issues.

I was expecting a fixed connector that gets disconnected with the panel removal but instead I've found that the panel is connected via a free connector on a loom.

I'm not sure if this is a factory setup or whether it was done as part of the recall I've heard was done on these cars in the past.

Can anyone offer any advice on how to remove this connector from the back of the instrument panel? It seems fixed tight and I don't want to force anything unless I am sure that I'm using the right removal method.
 

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Discussion Starter · #10 ·
Just an update to say if anyone else is trying to take off a tight pigtail connector off the back of the IPC hold down the connector latch on the bottom side of the connector and use a flat head screwdriver to slowly prising it up on each side.
 

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Discussion Starter · #11 ·
I've been running tests on the instrument panel and also the fuses mentioned above but so far things appear normal.

However I've begun to realise that what I'm looking for appears to be a short that is causing a parasitic draw and not a failed connection. The resulting low battery is what I believe is causing the immobiliser to fail on startup causing the car to not start.

I am about to carry out a parasitic draw test with a multimeter but wanted to verify something weird first.

When I pull fuse F3 (7.5A Dashboard/Immobilser fuse) with the car off, the headlights light up. Is this what happens on all Corsa Cs or is this not meant to happen?
 

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Yes the instrument panel lead is meant to be connect to the back and need unplugging once removed, this was the recall but some later ones would have been done in factory. I would guess the plastic on the dash behind the instruments looks quite rough cut where the plug would be? This is totally normal.

No your head lights should not come on when you re fit fuse F3, it does sound like you have a short somewhere or a bad earth somewhere? The head lights are not on the same circuit as F3 and the only common link would be the body control module BCM next to the battery which is common for water ingress and also where the indicator relay is which is on the F3 circuit.

Have you checked the earth ground points under the center console between the hand brake and gear stick and in
front of the gearstick? The one closest to but in front of the gearstick should be for the Immobilizer but it's worth checking them all.
 

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Discussion Starter · #13 ·
Just to clarify, the headlights are coming on when I remove the F3 fuse not when I re-fit it. When I re-fit it they go out again. I'm guessing the reason might be related to some circuitry on the F3 circuit overriding a short that is making them light when the F3 fuse is not present.

Another symptom which is probably related to why the headlights come on, and probably due to a short, is that the odometer LCD display is always on when the car is off and a faint beam light symbol is also showing on the instrument panel when the car is off. Is the BCM also responsible for what is displayed on the instrument panel?

Are there any guides/posts/videos online on how to access the said ground points on the center console?
 

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Do you have LED dash light bulbs? These can often cause the high beam light to appear to be on all the time and mileage display to stay on longer once you turn car off?

To remove the center console, chock wheels, release hand brake and pull it's gaiter up, slacken hand brake, pull up gear stick gaiter, remove inner front kick panels (2 x torx screws each) remove 2x rear torx screws, pop power socket out and disconnect wires, lift up rear of trim over hand brake, slide trim backwards and up over gear stick and out.
 

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Discussion Starter · #15 ·
I will check the ground points.Thanks for the instructions

I don't think I have LED Dash lights, they are just the factory originals from 2005. The beam light in the dash appears very faint, not on full like when the beams are actually on.

The mileage stays on all the time when the car is off, that's part of the reason I started suspecting a parasitic draw.
 

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Dash lights staying on is a common fault if the car has to lower wattage bulbs fitted anywhere so giving a lower current draw than the stock factory bulbs.
I'm not sure why they do it but it will also give a voltage/current error fault code in the instrument panel and BCM if you use a scan tool.
 
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