sierrafery said:
unfortunately for you the Td5 has a quite complicated electronic management and it's very hard to diagnose any management issue without proper tester... or it can be very laborious without any result...imagine how easy it would have been if you had one... by now it could have been fixed:cool:
Click to expand...

It's actually a very elementary assemblage of circuitry compared to some of the stuff I have to work on. But for a car, overly complicated I admit.
These testers, the high end ones I mean, do they ever return a "no idea, m8" answer? Even if it's only once in a blue moon?
 
let's put it this way, the tester is only the interface between you and the ECUs, it will tell you what the ECU stored as fault but there are some systems which are not covered by diagnostics like e.g. the fuel delivery or the mechanical parts when it will tell you nothing but at least you know it's not management issue... on the other hand the tester will be able to program the ECUs to make them work
 
sierrafery said:
let's put it this way, the tester is only the interface between you and the ECUs, it will tell you what the ECU stored as fault but there are some systems which are not covered by diagnostics like e.g. the fuel delivery or the mechanical parts when it will tell you nothing but at least you know it's not management issue... on the other hand the tester will be able to program the ECUs to make them work
Click to expand...

So... if the ECU turns out to be shot and I buy a new one, I still have to find someone with one of these devices to 'enable' the new ECU to work on my particular Landy? That's not a welcome prospect!
 
sierrafery said:
that's just how it is, better buy one
Click to expand...
Urgh! Can't do that. It would be like giving in. There must be some people in the UK who could set the new one up for me by post for a reasonable fee. I'll maybe do an online search if tomorrow's more exhaustive test of the crank sensor confirms it's good.
If I had more time it would be fun (my idea of fun, anyway) to do away with an EMU altogether and develop a much simper and cheaper controller to fire the injectors in sync from the crank sensor pulse train. It might be marginally less efficient, but some people aren't that bothered about that. Perhaps I could stick em on fleabay for 30 quid a pop; probably fly away.;)
 
better read the engine management description and operation mode in RAVE cos you simplify things too much IMO, it's not about simply fireing the injectors... it's a whole addaptive strategy based on 9 sensor inputs and the injection management is made according to a fueling ''map' saved in the ECM's EEPROM(and that's the most rudimentary explanatoin)
 
sierrafery said:
better read the engine management description and operation mode in RAVE cos you simplify things too much IMO, it's not about simply fireing the injectors... it's a whole addaptive strategy based on 9 sensor inputs and the injection management is made according to a fueling ''map' saved in the ECM's EEPROM(and that's the most rudimentary explanatoin)
Click to expand...

I'm happy to take your word for it! I have too many other projects on the go at present anyway.
Well, that's my lot for tonight. Testing will be resumed tomorrow... :)
 
TheMunster said:
Gordon bennet just get the thing plugged in, problem solved in 5 mins :)
Click to expand...

Well, if I'd have known at the outset that a new ECU would have to be reprogrammed with one of these devices, it would have put a different spin on the matter altogether.

Just going outside now to perform the final double-checks on the crank sensor...
 
Landlover99 said:
It's actually a very elementary assemblage of circuitry compared to some of the stuff I have to work on. But for a car, overly complicated I admit.
These testers, the high end ones I mean, do they ever return a "no idea, m8" answer? Even if it's only once in a blue moon?
Click to expand...

they don't tell you exactly what's what all the time. sometimes you can get no errors.

or you get things like bank failure of xyz; which can mean 1 of 3 things might be of issue.
 
trax said:
they don't tell you exactly what's what all the time. sometimes you can get no errors.

or you get things like bank failure of xyz; which can mean 1 of 3 things might be of issue.
Click to expand...

I'm getting the impression you need to know how to use these things to get the best out of them so not really suitable for a (hopefully) one-off use.

Well, I've tried another ingenious approach. This time I've used a low frequency sinewave oscillator to sub for the crank sensor. I've fed the ECU inputs with 2.7Vrms at 8hz (equates to about 500RPM) and.... zilch. Still no joy from the injectors.

The auto-electrics bloke rang up at that point and suggested as someone else has here previously that I eliminate the intertia switch and if that's ok, to bring it down, drop it off and let him get on with it. So that's the plan. I'm running short on patience, tbh.
 
to rule out completely the inertia switch circuit you should unplug it, bridge the pins iin the connector and measure if you have voltage on pin 22 of the ECM black plug(blue/red wire)

just re-read some posts of your's and i saw you checked the earths and crank sensor but did you actually check if the ECM has feed all around with ignition on which means pins 2, 22 and 33?
 
sierrafery said:
to rule out completely the inertia switch circuit you should unplug it, bridge the pins iin the connector and measure if you have voltage on pin 22 of the ECM black plug(blue/red wire)

just re-read some posts of your's and i saw you checked the earths and crank sensor but did you actually check if the ECM has feed all around with ignition on which means pins 2, 22 and 33?
Click to expand...

You're quite right about the switch of course. I'll do that. And I'll check for voltages on the other pins you mention, too.
 
Landlover99 said:
I'm getting the impression you need to know how to use these things to get the best out of them so not really suitable for a (hopefully) one-off use.

Well, I've tried another ingenious approach. This time I've used a low frequency sinewave oscillator to sub for the crank sensor. I've fed the ECU inputs with 2.7Vrms at 8hz (equates to about 500RPM) and.... zilch. Still no joy from the injectors.

The auto-electrics bloke rang up at that point and suggested as someone else has here previously that I eliminate the intertia switch and if that's ok, to bring it down, drop it off and let him get on with it. So that's the plan. I'm running short on patience, tbh.
Click to expand...

i usually just google for the codes and see what others have done. :D

but i went mechanical 300tdi with the landy, so i only need to bother with the electronics on the vag
 
sierrafery said:
to rule out completely the inertia switch circuit you should unplug it, bridge the pins iin the connector and measure if you have voltage on pin 22 of the ECM black plug(blue/red wire)

just re-read some posts of your's and i saw you checked the earths and crank sensor but did you actually check if the ECM has feed all around with ignition on which means pins 2, 22 and 33?
Click to expand...

Are you looking at some other diagram? Granted pin 33 is +V supply to the ECU, but pin 2 is a permanent ground connection and 22 is brown/orange here!
 
you are right i had a mental hiccup, mixed pin 22 with 21 and 3 with 2 :eek:

so again pins 3, 22, 27 and 33 black plug sorry
 
Last edited:
sierrafery said:
you are right i had a mental hiccup, mixed pin 22 with 21 and 3 with 2 :eek:

so again pins 3, 22, 27 and 33 black plug sorry
Click to expand...

If these are the three wires coded brown/orange shown tied together on the schematic, there are 0v on them with the ignition on. Pin 33 otoh, is reading 12V.
Is that right?
 
!!!! ....not at all these brown/orange wires must get feed from the under-seat fusebox fues F5 through the main relay's contact so if they dont have feed with ignition on that's your problem not the ECM, and that could be due to the main relay or if the inertia switch circuit is interrupted cos it feeds the relay's coil
 
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