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VDO or Bosch?

Posted: Mon Dec 03, 2018 4:55 pm
by punkCK
My van won't start, had to get RAC to bring me home last night.
Spent all day today fault finding everything I've found on the web, that can be a problem and narrowed it down to the pump in tank.
So, im gonna buy a new pump and have a go myself at fitting it.
Its gonna be tricky on the road with minimal tools and over half a tank full of fuel :[
Anyway, is VDO okay or am i better off with a Bosch unit?
Thanks

Re: VDO or Bosch?

Posted: Mon Dec 03, 2018 5:12 pm
by Doc
It's not very common for the in tank pump to fail, have you checked it is getting power to the pump? The wires to the pump are accessible behind the front left side seat, might be worth checking for voltage there if you have not already.

Which engine is in your caddy?
PD 1.9 and 2.0 use Bosch management so I guess the Bosch pump you have available will be best.
CR 1.6 and 2.0 use Seimens management so the Seimens pump will probably be best for those engines.
I think the VW part numbers are the same for both but maybe aftermarket replacement are more specific.

Re: VDO or Bosch?

Posted: Mon Dec 03, 2018 5:23 pm
by punkCK
Thanks for the quick reply Doc.
No, i have not checked the wires behind the seat, i had no idea they was there!
I thought they ran under the van.
Been through all the relays and even bridged the two large prongs on the 449 fuel pump relay and was no sound of pump.
i may just nip out now and have a quick look for those wires.
For info its a 2005 (55) 2KA, 1.9TDi BLS 104
Thanks.

Re: VDO or Bosch?

Posted: Mon Dec 03, 2018 5:28 pm
by astraman18
I m having the same issue with my van. 08 plate bls engine

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Re: VDO or Bosch?

Posted: Mon Dec 03, 2018 5:30 pm
by Doc
Did you have voltage on one side of the relay?
You should be able to check at the relay and you'll have supply voltage on one of the large terminal, the other will have pump motor winding resistance to ground. That'll prove the wiring for you rather than tapping into the wiring behind the seat.

Re: VDO or Bosch?

Posted: Mon Dec 03, 2018 5:52 pm
by punkCK
Doc wrote: Mon Dec 03, 2018 5:30 pm Did you have voltage on one side of the relay?
You should be able to check at the relay and you'll have supply voltage on one of the large terminal, the other will have pump motor winding resistance to ground. That'll prove the wiring for you rather than tapping into the wiring behind the seat.
No, i didn't check that simply checked the relay itself by swapping around with the other two 449's, and by feeling, hearing it click when ignition key turned.
i'll try that as just had a look at those wires and it will be a pig to do without removing the seat.
Thanks again.

Re: VDO or Bosch?

Posted: Mon Dec 03, 2018 6:13 pm
by punkCK
Hi Doc.
I have voltage on both large spades when ignition off, and no voltage from either when key in position 1?


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Re: VDO or Bosch?

Posted: Mon Dec 03, 2018 7:17 pm
by Doc
On the fuel pump relay:
Position 1 is permanent 12V from cabin fuse 43
Position 2 is switched supply out to pump
Position 3 is switched 12v from engine bay fuse 15
Position 4 empty
Position 5 is switched GND from ECU

Re: VDO or Bosch?

Posted: Mon Dec 03, 2018 7:27 pm
by punkCK
Maybe i'm not doing it right or my multimeter isn't good for 12v, but i can only read a voltage with the relay just pushed in a bit so as i can touch my probe onto the spades.
As i said above i read voltage on the two vertical spades (first 2 from left) and both horizontal spades but only when i have no key in the ignition.
When i turn the key to position 1 so all the dash lights come on and i can hear the anti shudder valve test itself, i hear the relay click on/off, but get no voltage from either of the vertical (larger) spades.
Another thing that puzzled me was in the space of 10 minutes of testing, the voltage went up slowly from 16 to 18.2v, and the relay was warm to touch even though the van was cold inside when i first tried it just earlier.
Any clarification please on if I'm testing it correctly?
Thank you

Re: VDO or Bosch?

Posted: Mon Dec 03, 2018 7:28 pm
by punkCK
oh, and all the fuses are okay too, thanks

Re: VDO or Bosch?

Posted: Mon Dec 03, 2018 7:35 pm
by Doc
Best option is to pull the fuse out.
Connect the negative lead of your meter to a good chassis ground point like the dash bar. Use a pin or narrow metallic object to probe into each position.
Test each position for voltage as I have given previously. Obviously the relay output won't do anything with the relay unplugged.
Then test the resistance on the relay output position leaving your negative lead on the chassis ground.

16V or higher is a concern for me, your battery shouldn't be that high and maybe this is your problem.

Re: VDO or Bosch?

Posted: Mon Dec 03, 2018 7:44 pm
by punkCK
Doc wrote: Mon Dec 03, 2018 7:35 pm Best option is to pull the fuse out.
Connect the negative lead of your meter to a good chassis ground point like the dash bar. Use a pin or narrow metallic object to probe into each position.
Test each position for voltage as I have given previously. Obviously the relay output won't do anything with the relay unplugged.
Then test the resistance on the relay output position leaving your negative lead on the chassis ground.

16V or higher is a concern for me, your battery shouldn't be that high and maybe this is your problem.
yeah me too! i thought it shouldn't get higher than 15-ish with the engine running ? and certainly not that high on a nearly flat battery, although previous owner said it is new. I've only owned the van for a few weeks now.
ill go check again now like you said. thanks.

Re: VDO or Bosch?

Posted: Mon Dec 03, 2018 9:10 pm
by punkCK
bizarre ?!?!?!
Fuse 43 was okay, but the bottom half of the terminal in the fuse board was pushed back.
So it was not even making proper contact!
Hey presto I'm bloody back up and running again.
Thank you so, so much Doc for stopping me in my tracks and saving me a small fortune.
I owe you a few pints pal :D

Re: VDO or Bosch?

Posted: Mon Dec 03, 2018 9:57 pm
by Doc
Nice one!
Another successful long distance diagnostics.
Glad I could help.