T4 wont start unless I close the relay?

[vma99r]

Hello, My Transporter T4 2.5 tdi does not want to start , it will turn over but not fire up. The glow plug light does not light up and the relays do not click. The local auto electrical garage sugested a new 109 glow plug relay , I tried that and no good. I took the cover off the relay and closed the contacts by hand and it starts as good as ever, only thing is that when I let go it stops , I tried to run it with the contacts cable tied together which was fine but when I checked to see if the glow plugs still were powered up they were... not good...
has anyboby had any problems with the fuse / relay carrier ? Please help. Pete.

[kenney]

Hi Yes i have replaced a few relay carriers on the T4.But relay 109 is not the glow plug relay,it is terminal 30 voltage supply.

[kenney]

Sorry, the glow plugg relay is 103.I think maybe you have a problem with the ignition switch

[vma99r]

Thanks, the reason I mentioned the relay carrier is that a few times it did not want to start I gave the relay a wiggle it started ok, then after that it would not. The only way to get it started now is to hold he contacts together.

[vma99r]

By the way what does terminal 30 voltage supply do?

[kenney]

Hi It supplys the engine control unit with current,that is why it stops and starts when you press the contact.To rule out the possibilty that it could be the ignition switch,bridge the black and the red wire behind your ignition switch,and see if that activates the relay,if it doesnt,then is the carrier that is at fault.

[vma99r]

Hello Kenney, I connected the two wires together behind the ignition switch and still no good, I bought and fitted a new relay/fuse carrier today and that has not helped either, now I am stuck - anybody any ideas?

[kenney]

OK Lets start with, is the relay in the right position (3)????? Remove the relay and using a voltmeter,with the ignition on,connect the voltmeter between terminal 1 and terminal 3 you should have battery voltage.

[vma99r]

Hello Kenney, yes the relay is in number 3 and their is 12.2 volts between 1 and 3. Pete.

[kenney]

With ignition off, relay out, connect voltmeter between terminal 4 and terminal 1,you should have the same reading

[vma99r]

With ignition off, relay out, connect voltmeter between terminal 4 and terminal 1,you should have the same reading


done this. the voltage is the same with the above connections.

[kenney]

Can you get the loan of a relay,that you know is working ok?.With the readings you are getting the relay should activate.

[vma99r]

Thank you for your help. I will try. I have fitted 3 genuine VW new relays with no luck. Sorry for delay in talking but now my computer has gone down so using a friends.

[kenney]

There is the possibility that there is a faulty earth,it can be good enough to give you a reading on the voltmeter,but not good enough to activate the relay,with the relay almost in try running an extra earth wire to terminal 1

[vma99r]

Thanks - just tried that and it makes no difference.

[kenney]

This one has me baffeled,there is only one last thing,but for the life of me i cant understand that it could be it,and that is the engine control unit,check the earth wires on it, there are 3or 4 and they connected at the one point.

[JONBOY201]

hi pete i'm a new user to this site & have the same problem with an 02 2.5 tdI transporter have you got it sorted????? john

[dtmdan]

Hi,

Likewise, new user to the site, 51 plate 2.5tdi (88bhp) Caravelle.

Hold contacts on relay, glow light comes on, goes out, can start van, release contact, van stops.

Too dark now to check voltages on carrier or short red&black on back of switch, also local dealer doesn't have a 109 relay in stock (computer says yes but ....)

Thanks for the advice posted so far, will let you know of outcomes when I've tried suggestions.

Incidentally, my VAG-COM did report 01314 ECU No Communications. Whilst I was still connected, heard a click from the fuse area and glow light came on, van started OK???? Puzzled as it won't start anymore

Cheers,

Dan:(

[JONBOY201]

Hi Dan, got the van sorted yesterday, you will probably find you have no switched earth to pin 5 on the relay board, this is for relay 109, this is a black/white wire & comes out of plug G1 terminal 7 & goes to the ecu 68 pin plug, the diagram says pin 42 but on mine it was pin 17. the wire comes out of the top right (o/s) loom in the engine bay & goes across the engine takes a little detor down the back of the engine then back over the gearbox. find the wire in the loom just before it goes down the back of the engine & pull it you will probably find it has chaffed then corroded. hopefully this is your problem. all the best john.

[dtmdan]

Hi John,
Thanks for your post and glad to hear that you've got you're problem sorted.
You mentioned a diagram - is this out of a manual or is it accessible on-line?
I have Autodata 2004 which is very sparse on info for the T4 and I have an older manual pre-dating my current model (previous was a 95M 2.4D). I don't know where the ECU is located and would appreciate a pointer in the right direction if you could help me?
Thanks again,:beerchug:
Dan

[carbon]

Hi Dan

The ecu in these vans is located in front of the battery, and should have a plastic cover over it.

[JONBOY201]

hi dan i got the diagram from a mate at vw not surpossed to have it you know what i mean!!!! have tried the auto data but not covering this model.
all the pin numbers are on the plug for the ecu.

cheers john
:beerchug:

[dtmdan]

Chris/John,

Thanks guys - I won't be able to get at the van before the weekend now as it's dark by the time I'm getting home. It's OK when I can work in the cab but not under the bonnet!

I'll post back with an update.

Cheers,

Dan

:beerchug:

[dtmdan]

Guys,

I've found a couple of pdfs containing wiring diagrams for the T4 - pm me if anyone is interested and I'll either send them on or send the link

Cheers,

Dan:biglaugh:

[vma99r]

Hello, back again after computer problems , had to wait for a new hard drive to be fitted.
I had to book the van into the main dealer in the end as I could not sort it out...
It turned out to be a broken wire between the relay and the ecu. It was the small black and white wire that earths the relay. They fitted a new wire and now it starts ok. I fitted a new fuse board for nothing ... what a bu..er. However I now have a new question please see on the board, thanks for all your help. Pete.

[basonjillett]

For DTMDAN could i get a copy of that 2.5tdi pdf
I tried to pm you but i havent got enough posts to be allowed !
I dont like to hijack threads but i dont know what other way of doing it

thanks Jason

[dtmdan]

for BASONJILLET

Sure, now that I've posted this, I can send you an e-mail with the PDFs

Dan

:biglaugh:

[vma99r]

Just thought I would give you an update, about a year after the orignal problem I had the glow plug light flashing at me from time to time, I booked it into the dealer and it turns out that the engine bay wiring loom is damaged, it is the part that Wobbles between the engine and the body of the van, I suppose after time the wires have started to break. ( 150.000 miles) In the end I decided to fit a new loom. I kept the old loom and sure enough you could see the dodgy bit, what a lot of wires!