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Discussion Starter #1
The car has been running fine, Until it was left for about a week.

Then come to use it, unlock the car as normal put the key into ignition and turn...... nothing
completely dead, no crack or anything then after a minute or so the fuel gauge drops to zero with a solid car/spanner light on.

I am confused and hitting a brick wall with it I have tried the following things:

-Charged Battery
-Cleaned Earths ( All that I can see including the ecu earth )
-Checked all the fuses ( All that I can see )
-Tried Pedal test ( No Luck - Use to work but no longer does )
-Checked ECU cables for Break / Corrosion ( None Found )
-Bump Start ( No Luck )
-I connected the car to OP-COM which will not pick up the car by Auto it display error no communication with ECM,

I then did the manual route >2007(7) > Astra H > Sub Menu's
I click on the CIM and it displays U2105-00 No Communication with ECM ( Engine Control Module )

If there is any tips or anything you can offer I would be greatful

I have attached a detailed DTC Check
 

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So your thinking along the lines of a CIM fault due to no authorisation being given to start ?
 

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"Red One.."
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Absolutely without doubt the focus of the diagnostic needs to be why the ECM isn't powering up. If you've got a multimeter, with the ignition off, check the resistance across pins 6&14 of the actual diagnostic plug. Should be around 60 ohms. This is a basic check to confirm the integrity of the CANbus wiring going to the ECM.

If one of the other guys on here doesn't before this eve, I'll check and confirm every fuse to have a look at that supplies power to the ECM, that'll be another first step too.

Failing that next areas are to measure voltages/earths at the ECM plug, and perhaps also lift and check the UEC for signs of water ingress.
 

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Discussion Starter #4
Hi Fred, Nick thank you for both comments,

I am unsure about the CIM with everything turning on. and in regards to checking the pins of the actual diagnostic plug do you have a diagram I could go off as I don't want to check the wrong pins and really do some damage.

I have checked the fuses and can't see any blown one's, I've also checked the UEC for signs of water ingress and can't see any, looks bone dry

Thanks
 

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If its not cranking over even, is the battery ok would be my first thought, you need to do some fundamental tests with multimeter...if your sure the battery and starter etc ok, i would suspect the Immobilizer is on, is there i light on the dash that is stuck on.....you could take the starter relay out and bridge 30 and 87 and the engine should crank, make sure its n neutral...from Fred in Essex.
 

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Discussion Starter #6
If its not cranking over even, is the battery ok would be my first thought, you need to do some fundamental tests with multimeter...if your sure the battery and starter etc ok, i would suspect the Immobilizer is on, is there i light on the dash that is stuck on.....you could take the starter relay out and bridge 30 and 87 and the engine should crank, make sure its n neutral...from Fred in Essex.
Hi Fred in Essex I have checked the starter with the wire trick and it tries to turn the engine and the battery was taken out and fully charged, The light I have on the dash car/spanner light solid, doesn't symbolize Immobilizer issue from what I've read, I haven't tried bridging the pins because I was worried of blowing something or causing more damage than fixing
 

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Discussion Starter #7
Absolutely without doubt the focus of the diagnostic needs to be why the ECM isn't powering up. If you've got a multimeter, with the ignition off, check the resistance across pins 6&14 of the actual diagnostic plug. Should be around 60 ohms. This is a basic check to confirm the integrity of the CANbus wiring going to the ECM.

If one of the other guys on here doesn't before this eve, I'll check and confirm every fuse to have a look at that supplies power to the ECM, that'll be another first step too.

Failing that next areas are to measure voltages/earths at the ECM plug, and perhaps also lift and check the UEC for signs of water ingress.
I managed to do the test with the multi meter set to 200k Resistence/Ohms settings, both pins displays 03.7, So either I've done it wrong or there is something i'm missing
 

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"Red One.."
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So you've put one probe into pin 6, and the other probe into pin 14.? You'll probably need to set the meter to 200ohms too if it's manual ranging.

Sometimes the pins of your meter won't make contact either as that pink plastic guard on the front of the plug is too narrow for the probes to pass thru. If so it can be gently removed, you'll see the contacts for the diag plug much easier then.

I would imagine you'll likely see either, the correct 60ohms, or a reading of around 120ohms.
 
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Discussion Starter #9
So you've put one probe into pin 6, and the other probe into pin 14.? You'll probably need to set the meter to 200ohms too if it's manual ranging.

Sometimes the pins of your meter won't make contact either as that pink plastic guard on the front of the plug is too narrow for the probes to pass thru. If so it can be gently removed, you'll see the contacts for the diag plug much easier then.

I would imagine you'll likely see either, the correct 60ohms, or a reading of around 120ohms.
Oh no sorry I'm not that clued up so misunderstood what you said and someone on a forum said Red probe into pin and Black probe to earth, If you would like I can do both into pin 6/14 , Correct me if i'm wrong but this is the diagram I followed.
 

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"Red One.."
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No that's absolutely fine, and it proves the physical integrity of the CAN communication wires, that there isn't any shorting out of the network.

The following fuses in the UEC provide power to the ECM:

FE30 (10amp)
FE21 (20amp)

Check these with the ignition switched on and the fuses in place, measure voltage on the exposed contact at the top of the fuse with the red probe whilst black probe on the battery negative. Both should be battery voltage.

Both these fuses are supplied with power from the ignition relay and ECM relays respectively, if you're missing a voltage at these fuses then it can be followed back from there, if you do have the correct voltages then you can start checking at the ECM if you're confident going further with the diag.
 
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Discussion Starter #12 (Edited)
sorry about the late reply, did as you suggested and the FE21 is dead, nothing what so ever.

I taken the fuse out and checked to make sure it wasn't blown and it wasn't, the fuse is fine

Where about's do i look to rectify this ?

Thank you so much for all your help so far
 

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"Red One.."
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Okays, remove the relay in the UEC I've shown below (it'll likely be a square, black relay), and with ignition on check the terminals shown with the black squares for battery voltage (with negative lead on battery terminal as before). Both should have voltage:

Screenshot 2017-02-21 20.56.011.jpg


If they do, find a decent piece of wire and bridge the terminals now shown below in red, and see if your car then bursts into life:

Screenshot 2017-02-21 20.56.01.png
 
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Discussion Starter #14 (Edited)
Tried what you suggested, Both pins show power/voltage, I tried the bridging but that does nothing, no crank no start nothing, same as before.

cant hear anything working when I try and bridge it

Now more confused than ever
 

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"Red One.."
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Just to confirm, both pins showing circa 12v, or whatever voltage the battery is roughly at?

Okay so I think what I'd do now is to keep the bridged wire in place and then recheck the voltages at fuse FE21 as previously (you definitely had a good contact on this fuse when you checked it initially?). Basically what you're trying to do is trace backwards along the voltage supply as to where the supply for the ECM is being lost - by bridging those contacts across you're bypassing that relay and sending power to FE21 without the relay in place.
 
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Discussion Starter #16 (Edited)
both pins show 12v, Previously I taken the plastic off the top of the fuse for direct access.
Used the same method this time to check the voltages.

I have just checked again with doing the bridging and now the FE21 show's voltage of 12.67
the moment the bridge is taken away the voltage drops to 0

hopefully nick you have some more tricks up your sleeve
 

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"Red One.."
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Okay, so with the bridge in place you now have voltage at the fuse whereas no voltage existed before this.

The way that ECM relay gets switched on, in order to route power down to the control unit is via an earth supply from within the ECM to energise that relay (so the ECM essentially grounds the relay to then provide power to itself) - the results so far are showing that this ground is not being provided.

More diagrams - this is the wiring diagram for the relay (K2_X125):

Screenshot 2017-02-21 23.00.56.png


And this is what you've done so far, removed the relay and bridged the wire (orange), and confirmed battery voltage under load (circuit connected..best way to test.!), shown as far as you've checked, in yellow:

Screenshot 2017-02-21 23.00.561.jpg


That supply wire then continues into the engine loom where it splits into three wires and feeds three terminals of the control unit. Next logical step is to check those voltages are being received directly at the ECM, but before that....

....Are you getting any form of communication on Opcom now with the ECM, with that wire bridged? Does the pedal test now work? And have you had the UEC lifted and removed for inspection.? Is the lid of the UEC secure when fitted, are the clips intact and holding the lid firmly in place normally?
 
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Discussion Starter #18
Wow, straight over my head.

No I understood it a bit...

I tried the opcom with the bridge in place and still the same (u2105 - No Communication with ECM) , I haven't tried the Pedal Test, Would you like me too ?

Not checked the UEC Again as I checked earlier and no signs of water and its securely fitted with clips intact and holding.
 

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"Red One.."
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Hehe if I'm going too fast just say so, just trying to lay it out so it's not just 'check this check that' kinda thing, but to give a little understanding too. If you're still not getting comms with the ECM in Opcom then doubtful the pedal test will work.

Just to confirm BTW, the engine code for the car.?? I ought to be 100% as one of the 1.6's has slightly differing wiring.
 
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Discussion Starter #20
Lol no it's fine at least this way I'm starting to understand and learn about my car.
I wish I could give give you the engine code but I have no idea of how to find that, I haven't got a car pass , Service Booklet states: New Astra 1.6i 16v VVT SXI 3DR

75141552
Star Silver
***REG***
197

I hope that helps if there is anything else i'll gladly help if I can
 
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