Grr, VAG-COM won't see engine ECU (sorted, found bad CPS)

[Funkster 0]

Hi all,

 

I've got *very* variable performance at the moment (feels like ~30 ponies coming and going from one minute to the next sometimes) so I thought I'd scan for fault codes. I've got a lead that has worked before but I had to scare up a different computer as the previous laptop wasn't mine.

 

So, got the version installed that I think I had before (just demo at the mo), v311.2, and had a go... it'll read fault codes from the ABS ECU, and when I click on Engine something goes clickity click behind the dash, but eventually I just get the "No response from controller" message.

 

Have I missed something really obvious? The engine has been out a couple of times since I last read faults, but the engine ECU has never been disturbed.

 

Thanks in advance for any hints, apologies if I've just been a numpty and done it all wrong!

 

Cheers,

--

Olly

[quicky1980 0]

if its a non vr6 engine, you may only be able to read abs faults. someone might correct me on that soon

[Funkster 0]

Aye, it is a VR6 - I've read fault codes on it before, just not this time (

 

Cheers,

--

Olly

[Supercharged 2]

Same laptop / lead / software / baud configuration as used before? (ie nothing else changed?)

 

Change the ECU relay!

[Funkster 0]

Different computer, and is there a setting for the baud? I didn't see one in the options.

 

Would the car run if the ECU relay was faulty?

 

Cheers,

--

Olly

[Reggit 0]

You don't have an immobiliser active when you're trying to read it do you? Some of them interrupt the communications between PC and car.

[was8v 0]

I have exactly the same problem. I was going to try sticking a pin through the K line (grey+yellow?) off the ecu connector directly, hook the 12v and gnd up and try and read it that way.

 

Didn't know about immobiliser or ecu relay problems, I'll give those ago first.

[Funkster 0]

Ooo, yes the immobiliser would've kicked back in by the time the PC booted up, and I'm pretty sure that last time I managed to read fault codes I was still on the factory immobilser - now replaced with a popular aftermarket one.

 

I'll try disarming and see what happens )

 

Cheers,

--

Olly

[Mystic Rado 0]

Second the immobiliser thing - just installed VAG-COM on a Macbook using Boot Camp and it wouldn't read the ECU with the alarm LED illuminated, as soon as I switched it off, all worked fine. Or on the engine side it did, ironically it had trouble scanning the ABS :?

[CrazyDave 0]

If your laptop needs a USB serial converter, you can have problems with cheap converters that don't support all the baud rates that VAG-COM needs.

 

I had a similar problem when I changed from a laptop that had real built in serial ports to one that needed a USB converter, I tried two before finding one that worked with all cars. On my Golf I could see the Engine ECU, but not the instruments, ABS or central conv. Not a problem since finding a decent USB Serial lead.

 

The immobiliser must be clear and the ignition on or engine running to get communication with VAG-COM.

[Funkster 0]

Many thanks for the help all - pressed the unlock button and all was well. Glad it was something daft :oD

 

Alas, I now know that I have an intermittent cam sensor open / short to B+ which explains the variable horses. I wiggled the plugs and it didn't go away so I guess I'll spike the wires with the 'scope later and see if the sensor is really dead... do they tend to spontaneously fail? The sensor was sat on the shelf for quite a while when I was rebuilding the engine.

 

Cheers,

--

Olly

[CrazyDave 0]

Mine failed about 3 days after I replaced the coilpack. It was one of those 'great, more expense' moments :D

[Funkster 0]

Expense indeed! At £36 from the stealer I think I'll make sure mine is *really* dead before replacing it...

 

Now, where's me pins?

 

Cheers,

--

Olly