T25 DG ECU Test

An alchemy of sparks, copper wire and earth

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edconeng
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T25 DG ECU Test

Post by edconeng »

Hi this is my first post.
I have a T25 Syncro 1988 with a 2.1 DG Pertol Engine, I had a gearbox issue and the Bus has been laid up for a few years, I am now in a position to get it up and running again.  But !
My problem is that there is no Spark or Fuel Injected so I suspect the ECU, does anyone know where I could get it tested ?? as I don't want to fork out £500 for a new one and find that this is not the problem .  ( Before being laid up it worked perfectly.)

Thanks in advance.

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Re: T25 DG ECU Test

Post by davidoft1 »

I would suspect the distributor

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Re: T25 DG ECU Test

Post by edconeng »

OK, will check out the Distributor.  Would that affect the ECU not initiating the Fuel Injection ?         When I wind the Engine over there is no smell of Petrol and the Plugs are Dry.

Ed.

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Re: T25 DG ECU Test

Post by davidoft1 »

edconeng wrote: 19 Jul 2021, 14:41 OK, will check out the Distributor.  Would that affect the ECU not initiating the Fuel Injection ?         When I wind the Engine over there is no smell of Petrol and the Plugs are Dry.

Ed.

the ecu picks up the signal from the ignition system,, check your wiring and if you have ignition feed to the coil 

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Re: T25 DG ECU Test

Post by edconeng »

OK, did the following, :-

Ignition on.....12V at Coil

Bypassed the Idle Control Unit   (Male to Female Plugs connected)
Ignition on...   12Volts between pins 2 & 4 at Ignition Control Unit

Reconnect Ign Control Unit  
Disconnect Distributor Plug
Ignition ON.......  Not getting any voltage accross outside pins at Distributor loom plug, (my manual states min 2V for 1-2 seconds).

Any Help ?????????

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Aidan
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Re: T25 DG ECU Test

Post by Aidan »

edconeng wrote: 19 Jul 2021, 17:10
Bypassed the Idle Control Unit   (Male to Female Plugs connected)

Reconnect Ign Control Unit  


do you mean reconnected Idle control unit (digital retard)

if so have you tried running the engine with the idle bypassed ?

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Re: T25 DG ECU Test

Post by Mocki »

Earths to the ECU .
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Re: T25 DG ECU Test

Post by edconeng »

Aiden, the engine will not start. 
 The bypass of the idle control unit was as instructed in the 'VOLKSWAGEN VANAGON Official Factory Repair Manual' to test voltages for fault finding only.

Ed.

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Re: T25 DG ECU Test

Post by edconeng »

Moki,  I will check out the Earhs tomorrow.

Thanks to everyone giving me advice.

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Re: T25 DG ECU Test

Post by edconeng »

The Factory Repair Manual I am using is the one published by Bentley Publications covering the Vanagon 1980 through 1991.
Obviously American, A4 size about 2" thick.

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Re: T25 DG ECU Test

Post by maxstu »

Do you have initial fuel pump prime on turning key? If yes....
Check ECU earth in multi pin connector loom. Pins 25 and 7 l think. Multi meter across these and check resistance. And check earth in engine bay. Also check Hall sender signal too.
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maxstu
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Re: T25 DG ECU Test

Post by maxstu »

This is where l would start.

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Re: T25 DG ECU Test

Post by PaulM99 »

Hopefully you're running by now.  Had an issue with my 1.9 wbx last year where all of a suddenty the engine turned but no ignition.  Had a mechanic chum who spent 45 minutes looking at it to no avail.  Finally called out AA and an older chappie arrived.  He happened to have a similar ECU (not that he knew it was any good) on his van and changing it out had no effect.  45 minutes of scratching head and turning it over he finally put a socket on a thin earth wire on the side of engine block and it sparked.  Took off, cleaned up, gave it some electrical-contact-jollop and reconnected it and away she went.

Really thin & innocuous wire that almost seemed like a redundant thing (like so much on the old bus-previous owners have added and taken away without always following through).  Very easily overlooked

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