Corsa poor starting and cutting out

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Corsa poor starting and cutting out

Postby Bopbop » Fri Aug 26, 2016 4:33 pm

Hi i am having problems with a vauxhall corsa 1.2 xep. It came is as a non runner. I had to carry out repairs to the timing chain and water pump. I have renewed the wiring to the instrument panel as i thought this was the issue. There is a permanent fault code B1485. I have checked for the correct canbus signal at the instrument panel and it starts out ok then goes into a wobbly. I have attached a file (i hope) any advise would be greatly appreciated. Regards Ian.
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Re: Corsa poor starting and cutting out

Postby STC » Sun Aug 28, 2016 10:42 am

Ian

You have provided very little information to work with

it starts out ok then goes into a wobbly

What does that mean ???

Last time I saw B1485 (Exciter current generator terminal 61) on a similar Corsa it was charging ok. The only symptom was the battery light illuminated on the dash. TIS Guided fault finding IIRC looks for confirmation that the alternator is good and the wire from alternator to BCM is intact and then tells you either the BCM or ECU is faulty. In my case a new BCM didn't fix it so I took it off put an ECU (Engine) on and it fixed.

Your scope waveform is good, which we can take for granted if we have global communication & no fault codes for bad CAN, Missing Messages etc.

Someone here maybe able to help you further if you were to post the results of a global scan and describe the fault with the car with some detail and relevant measured values.
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Re: Corsa poor starting and cutting out

Postby steevegt » Sun Aug 28, 2016 11:45 am

The B1485 code comes (at least) in 2 different types (low voltage and high voltage).
Witch one do you have?

Is this the only problem with the car?

STC, in this case, the alternator is connected to the BCM? I checked a wiring diagram for this, and I can only see a connection from the alternator to the ECU. It may be incomplete I guess.
In this case the BCM must be getting the alternator status from the ECU, right?
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Re: Corsa poor starting and cutting out

Postby STC » Mon Aug 29, 2016 4:47 am

I was working from memory in my previous post.

I have just fired up TIS to double check what is what.

Assuming this is a Corsa C - 2005 - Z12XEP then we have 3 flavours of B1485
Exciter current generator terminal 61 - High Voltage
Exciter current generator terminal 61 - Low Voltage
Exciter current generator terminal 61 - Circuit Open

The fault code, (and variations of) are listed only in Body Control Module, nowhere else including Engine ECU. The affected wire runs from alternator to BCM Pin (X46) 95. I suspect that BCM will broadcast that info onto the CAN Networks

Guided fault finding looks for confirmation that the wire is good, Battery Voltage is >11v, Charging Voltage is 13-15v.
If the above are correct then TIS Condemns the BCU, then you are out in the cold guessing which ECU to replace next.

Lovely position to be left in ?

Been a few days now! Has OP Bailed ?
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Re: Corsa poor starting and cutting out

Postby steevegt » Mon Aug 29, 2016 8:45 pm

The affected wire runs from alternator to BCM Pin (X46) 95.


You are completely right. I just confirm. I was looking at a difrent car when I saw the connection to the ECU. Only explanation. Sorry for that...

I suspect that BCM will broadcast that info onto the CAN Networks


I believe the BCM will at least broadcast the alternator status for the light in the dashboard.

Doesn't the ECU need to broadcast also the engine running status to the BCM, in order for the BCM to properly diagnose the alternator D+ signal? Could this be known by the BCM from a different source, or info? RPM signal in the bus? Wired connection from ECU to BCM?
Why the ECU could cause a B1485, if not from a bad knowledge of the engine running status by the BCM?
Just trying to link the ECU fault with the B1485....

If the above are correct then TIS Condemns the BCU, then you are out in the cold guessing which ECU to replace next.

Lovely position to be left in ?


This should be better documented by the manufacture. How can we do properly diagnosis in this case without guessing or very deep digging?
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Re: Corsa poor starting and cutting out

Postby Bopbop » Tue Aug 30, 2016 8:54 am

Hi Sorry about the vague description. The fault code is B1485 low voltage. It is the only code i have in any of the systems on the vehicle. The vehicle will start but very very badly. When running it will start to run poorly misfiring and popping when you try and increase the throttle. The loss of the canbus signal from the file i have uploaded coincides with the poor running and eventual cutting out of the engine. I have already replaced the engine ECU so reading it looks like it may ow be a BMC problem.
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Re: Corsa poor starting and cutting out

Postby STC » Tue Aug 30, 2016 12:20 pm

This should be better documented by the manufacture. How can we do properly diagnosis in this case without guessing or very deep digging?


If you have ever used Vauxhall / Opel Tis (WD & GFF) You will know what I mean if I say it is Very Good & Very Bad at the same time.

On the Corsa I worked on, From memory, so dont quote me, I think I had another fault in Engine ECU which led me to replace the ECU, which was an easy call to make knowing that the BCU was new. The garage had already put a Battery and Alternator on it. I did take the New BCU off and kept it in stock. The fault remained fixed. It was the ECU that cured it.

As for Very Deep Digging - How do you Dig any Deeper unless you start to decode CAN Messages or throw bits at it ?
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Re: Corsa poor starting and cutting out

Postby STC » Tue Aug 30, 2016 12:46 pm

Ian

Our two posts above crossed.

Hi Sorry about the vague description. The fault code is B1485 low voltage. ... The vehicle will start but very very badly.


Sorry but still vague ! Does it get better as it warms up, is it driveable ? .......... ............ ............

The fact is that it came to you with a Chain fault, had it jumped ? There is a good chance the poor start fault is under that chain cover. Vacuum Guage on Manifold ? MAP reading at idle ? (if it has one) Measured Values ??

B1485 is not going to cause your car to start badly. Neither is it a CAN fault. Cant see a new BCM curing the starting / bad running fault. Zip up your wallet for now and stop bolting bits on it. It will make it harder to fix
It is the only code i have in any of the systems on the vehicle.

What Diagnostic tool are you using ? Which Controllers do you have access to ?

How many Channels on your scope ?
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Re: Corsa poor starting and cutting out

Postby Bopbop » Tue Aug 30, 2016 2:16 pm

Hi the car came in as a non runner. I checked the valve timing as a precautionary measure it was found to be quite a way out so a new chain kit was fitted. Also a new water pump. If the vehicle is warm it will start easier but still cuts out. Once cold sometimes it kick and starts other times nothing. All compressions are good. No Map sensor. When it starts it runs ok for 1 or 2 minutes then it starts to falter until it eventually stops. My scope is 4 channel and i have been using opcom as a scan tool. One thing in live data i have noticed is the "spark timing" seems to wander erratically all of the time. If you look at my file i uploaded the vehicle is running ok then it seems to lose the can signal when the engine stops is when the can signal returns. The charging light does illuminate and also goes out. Perhaps i am barking up the wrong tree but it is the only thing i have to work on. Thank you for replying i understand your time is important to you.
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Re: Corsa poor starting and cutting out

Postby steevegt » Tue Aug 30, 2016 2:49 pm

STC wrote:As for Very Deep Digging - How do you Dig any Deeper unless you start to decode CAN Messages or throw bits at it ?


That was my definition for very deep digging. But I guess that is impractical... Or isn't it?
Never saw anyone doing diagnose work based on can bus frame data... Except checking for valid CRC I guess.
Maybe in the future, diagnostic work are going/need to be doing more stuff based on the frames data itself... Who knows...
Without documentation from the manufacture, that is going to be hard...
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