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Matt
Matt, Mechanical Engineer
Category: UK Car
Satisfied Customers: 21360
Experience:  BEng hons Mech engineering, in auto industry 22 years
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I am looking at a discussion you had my problem is nearly

Customer Question

Customer: Mark, I am looking at a discussion you had http://www.justanswer.com/uk-car/8cgrq-lupo-hi-lupo-tdi-amf-won-t-start-the-engine-cranking.html#re.v/462/ my problem is nearly identical
JA: Thanks. Can you give me any more details about your issue?
Customer: I have tested the voltage across f37 and it is only 0.5V
JA: OK got it. Last thing — JustAnswer charges a fee (generally around $30) to post your type of question to UK Car Experts (you only pay if satisfied). There are a couple customers ahead of you. Are you willing to wait a bit?
Customer: yes, in the transcript, he sent a wiring diagram, there is no link on here I would like that too, if possible
JA: OK. Now I'm going to take you to a page to place a secure deposit with JustAnswer. Don't worry, this chat is saved. After that, we will finish helping you.
Submitted: 1 year ago.
Category: UK Car
Expert:  Matt replied 1 year ago.

Hello

OK looking at that other thread, 1st thing to check is if the power to the ECU is present ?

if you use a voltmeter on the ECU power fuse with the ignition on do you have 12V?

if you do then then next step is to inspect the wiring to the crank speed sensor on the flywheel / gearbox end of the engine

let me know what you find?

Customer: replied 1 year ago.
The Car is Vw Lupo, 1.4TDI, 2001Where will I find the fuse for the Ecu?There are a number of fuses which the symbol suggests deliver power to the engine in some way.To give you the background,About 8 months ago the glow plug light would not come on when starting and the fuel pump would not prime, thus the car would not start. This was very intermittent but could be solved by beeping the horn. As soon as the horn was pressed the glow plug light came on and the engine started.This happened more frequently. About a month ago, beeping the horn stopped turning on the glow plug/fuel pump.Now I can't get it to start, I have taken the 109 relay out it looks like new inside, I put it in without the plastic cover so I could force the solenoid, made no difference?In the thread that I copied to you you sent a circuit diagram, could you send it to me, too?Regards Charles
Expert:  Matt replied 1 year ago.

Hello

the ECU fuses are fuse 23 (glow plug module) in the fascia fusebox ( by the driver knee) and 32, 36 & 37

and the ECU relay is number 11 in the fascia location

and I've attached the ECU pinout diagram

Expert:  Matt replied 1 year ago.

also have you tried checking on fuse 40 in the fascia as this is for the fuel pump?

as it sounds like the root cause of it not starting is the fuel pump not running

Expert:  Matt replied 1 year ago.

Hi

do you still need help?

Bear in mind that the site takes a deposit from you at the beginning and this is held by the site until you rate my answer at which point the cash is split between the site and the expert. I am only paid for my work on this question if you rate my answer, using the star system at the top of the screen. Please do not forget! Thank you

Customer: replied 1 year ago.
HiMatt sorry it has been a while since I got back,The car is not in a garage so I am quite limited when I have the time to look at it,Here are the results, I checked all the fuses for resistance they are all fine,Voltage across fuses (battery check 12.1V)F23, ignition off 0V, ignition on 0VF32 ignition off 0V, ignition on 11.2VF36, not there, no wiring for this fuseF37 ignition off 0V, ignition on 0.5V,F40 ignition off 0V, ignition on 0V,Rely 11 is the 109 relay mentioned earlier.There is 12V on the power circuit, but no voltage on the switching circuit.I have taken this relay out, removed the plastic cover and manually forced the solenoid, this makes no difference,I have also taken the relay out and connected the power circuit with wire to ensure connection this also makes no difference.I have been trying to find the tandem fuel pump under the bonnet with no luck the I could try to give that power directly. I can't even find the mechanical pump, which I am sure must be adjacent to the cam belt.With regard to the rating which you have mentioned, I am happy to rate you and ensure you are paid whatever the outcome,What would you suggest next?Regards
Charles
Expert:  Matt replied 1 year ago.

Hello Charles

this rather sounds like the tandem / lift pump isn't being powered up?

if you remove the fuel filler cap and flick on the ignition the pump should run for a few seconds

its located under the back seat and inside the fuel tank, lifting the back seat cushion will reveal a inspection hatch and under that will be the pump terminals

if you then run a 12V wire direct from the battery to the pump and it all springs to life then this would confirm this

the reason for this can be that the security system isn't disabling correctly? and I suspect the issue is with the ignition switch so I'd remove the steering column plastic trim and check over the wiring to the switch as the next thing and there is a 'conveinence unit' which handles the signal from the key fob and disarms the security

sadly replacing these is a job for the dealership as your existing keys will need 'coding' to the new unit for it all to work

Expert:  Matt replied 1 year ago.

Hi

do you still need help?

Bear in mind that the site takes a deposit from you at the beginning and this is held by the site until you rate my answer at which point the cash is split between the site and the expert. I am only paid for my work on this question if you rate my answer, using the star system at the top of the screen. Please do not forget! Thank you

Customer: replied 1 year ago.
Finally I have had chance to get back to the car,The fuel pump and is definitely not being switched on buy the ignition which I was aware of, with this also not the glow plug circuit which I think are connected.I have got to the electric fuel pump under the seat I have taken a direct supply to it and it switches on and off no problem.I have taken all the plastic trim off around the steering column, I cannot find any obvious damage to wires etc.I have removed the plug from the back of the ignition key barrel.I have manually cross wired this, to get the ignition lights to switch, to get the starter motor to work. I tested the voltages between all the connections and the middle pin which it the positive.There was 12v on all pins apart from the top middle one, this had a grey wire going into it?
not sure if this helps?Regards
Charles
Expert:  Matt replied 1 year ago.

Hello

I'd try tracing the wiring a bit further down the column to check for shorts and damage

as for the car to have been working when you beeped the horn I suspect that there's some damage

now this could be a faulty security module or a just a wirign issue from the ignition switch

Customer: replied 1 year ago.
I will have a look, thank youWhat I forgot to say was that, I don't think there is any security device fitted, there is no key fob, and I have never experienced any immobiliser issues before.
Expert:  Matt replied 1 year ago.

there's a chip in the key thats recognized by the central locking module located in the fascia, this allows power to the ECU and other components

Expert:  Matt replied 1 year ago.

Hi

do you still need help?

Bear in mind that the site takes a deposit from you at the beginning and this is held by the site until you rate my answer at which point the cash is split between the site and the expert. I am only paid for my work on this question if you rate my answer, using the star system at the top of the screen. Please do not forget! Thank you

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