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Discussion Starter #1
Hi there,

New to the board wanted to start a thread for some help on starting issues I have with my 2002 Golf Mk4.

Replaced the starter motor on it about 4-5weeks ago and it worked okay for about a week and half and then it failed again. Part was under warranty so I brought it back to the Mechanic and it was replaced with a working part which subsequently failed again.

Mechanic had a look at it and has done as much as possible by testing all the relevant parts and has suggested bringing it to an Auto-spark [Car electrician] to check if there is something to be done there. Mechanic advises this may have something to do with the ECU but is unsure and also advises that establishing the root cause of the problem could prove to be a costly and unworthy exercise and recommends that I should scrap the car.

I want to take the car back and have a go at trying to get it back up again, and whilst I'm not savvy on the details of what he has ruled out and not ruled out (apologies in advance), and based on what I've explained so far, does anyone have any ideas?

Appreciate it may not be much to go off but any pointers in direction?

Having done some reading around, I've seen the term 'Holy Trinity' which seems to entail the fact there are a combination of jobs involved with replacing an ECU. Also the fact that each part number is specific plus the job of ensuring the ECU is coded/mapped correctly etc.

If it is the ECU, how difficult of a job is that - what does that involve? What else should I be aware of?
 

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The car was starting absolutely fine, first time everytime until one day it went completely dead. As in, no crank, no tick, no nothing just straight up no sound. Figured it to be the battery but with a power pack on it the battery, still nothing.

Established since the car bumped, it must have been the starter motor. That was replaced and it was working fine for about a week and half, first time everytime and then completely dead again one day. Few clicks before the clicks eventually ceased and the result was the same as above, just dead, nothing.

The Mech got it started by giving the starter motor a whack with his tool and having a powerpack on the battery. Obviously that's not ideal.

Replaced starter motor again and it worked for about a day, then same result.

At this point everyone was under the impression it was faulty startmotors because everything else was checking out. However, after examining it over the last few weeks, and replacing the start motor again, the same symptoms persisted as per above and has said that it works 9 times out of 10.

The Mechanic recommended bringing the car to a car-electrician [Auto-Spark] in order to find the root cause of what is causing this issue to persist because the battery, wiring and motor are all apparently fine. However, mentioned that it could be a wild goose chase and could end up spending hundreds for no good reason.

I want to know if anyone on this board knows anything abundantly obvious or could point me in the right direction in order to educate myself so that I may have a go myself.

If that's completely stupid and crazy, feel free to say that to.
 

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Obviously, the battery, wiring and motor can't all be fine otherwise you'd be cranking. ("fine" doesn't mean anything to me- and it shouldn't to you either; specifics of what was checked and what the MEASURED results were)

When you weren't getting any clicking etc. what dash lights were you getting?

I'd check all your connections in the fuse panel that's on top of the battery. I'd also remove the battery and clean the grounds that are underneath the battery tray.

You've got an intermittent electrical issue. Grounds are usual suspects.

If you've got a good/new starter there's ZERO reason to smack it! No idea why your mechanic would do that (knowing that the starter is good). If that is the correct starter and it was installed properly (not skewed, which would cause it to bind - and, really, if this were wonky you'd likely hear some nasty engagement noises).

A bad 109 relay will cause starting problems, but I believe that generally they'll still allow the starter to get power.

In general, you've got to get consistent power to the starter. If there becomes an instance in which the starter makes ZERO sounds (no solenoid, no power getting to it) then perhaps try jumping power to it. If the car then starts and runs and shows no other signs of problems then the problem is likely only in your starter circuitry; this still could, however, involve your ECU (wiring is known to present troubles here- rodents can help speed up failure).

Lastly, has anyone scanned for logged codes? This is probably the first thing that needs to occur.
 

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Discussion Starter #5
Thanks for the prompt reply - I was just on my way to collect it so I took note of some of your points and asked Mech about it.

When I say fine, it was working without fault until it wasn't, but yes you're right, it's obviously not fine.

The assumption was that the starter was faulty which was an assumption that was ruled out only ruled out after but again, you're right, should not be whacking starter motors if they are operating correctly.

Mech explained that all wires going to the starter, to the ECU and earthing-grounds off the body had been checked and ruled out. I asked about the relays and he said he ruled that out too. I also asked about the diagnostics to which he said no codes were coming back, that basically all was well.

When issue occurs there are ZERO sounds but car will start upon jumping.

In essence, the Mech maintained that his best guess was that it is either an issue with the ECU or Ignition because they were certain anything to do with wiring was ruled out and that they were either checked, cleaned and or replaced where necessary.

When I picked the car up, it started first time.

What do you think?
 

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Sounds like your mechanic (other than whacking the starter!*) has done a good job here. ECU issues, while they can happen, are fairly rare. More likely, and your symptoms seem to follow, it's your ignition switch. Take a look here:

https://pics.tdiclub.com/data/500/A4_Ignition_Switch_Replacement.pdf

Switches don't like a lot of weight hanging off them, in which case it's good to not have a bunch of stuff dandling off your key ring: I have ZERO stuff on mine.

*NOTE: On an old starter it's OK to do this as they do tend to get a little sticky (esp on manual transmission cars- clutch dust).
 

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Discussion Starter #7
Awesome thanks for the walkthrough.

However, whilst it was with the Mech he only ever had one key so do you think then it's a case of what you're saying in terms of the weight and over time said weight has deteriorated the ignition/barrel which is subsequently causing the ignition to be temperamental ( I.E it starts 9/10) ?

Just to clarify, we're pointing towards the ignition mainly because the engine light is not turning on and the diagnostics are coming back okay? I.E that's not something you'd see on a dashboard / picked up on a diagnostic and upon ruling out all the wiring obstacles, can only suggest the ignition? Does that sound about right?
 

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Clean the ground on top of the transmission. Jumper a wire temporarily in place of the B+ to the starter.That wire sometimes rots from the inside. Check for 12v on small wire to starter when you hit the ignition switch.
 

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If the mechanic got the car to start by hitting the starter possibly they wiggled a loose wire causing it to temporarily function.
 

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Discussion Starter #10
Clean the ground on top of the transmission. Jumper a wire temporarily in place of the B+ to the starter.That wire sometimes rots from the inside. Check for 12v on small wire to starter when you hit the ignition switch.
As far as I know the Mech cleaned and ensured all electrics in and around the battery & starter going to the ignition were good. He made a big point of telling me that and explained that the outstanding troubleshooting was with either the ignition or the ECU.

I'm thinking, especially as per the other points in this thread, that it is not the ECU because Mech also reported no log codes and there has been absolutely no dash lights either.

UhOh pointed towards the Ignition Switch and I thought that was a good place to start so I got one of those and I'm going to try and fit it myself on the weekend.

It's also important to note that this is an infrequent occurrence I.E it will start NP first time 9 times out of 10 and then it will do this the 10th time until it decides it wants to be cool again. Which is why I take the point on the Ignition Switch, could just be in need of replacing.

In order to be a bit more robust however, and for my own understanding, I did go and look up some videos on ignition diagnostics to which the videos talked about certain relays [Specifically - 53 / 109 / 185] all of which are inexpensive so I was considering just replacing them.

Seen that it also talked about the Clutch Pedal Position Switch - and whilst I don't think my car has that issue (It's a MT btw) I was thinking of getting one of those too.

If the mechanic got the car to start by hitting the starter possibly they wiggled a loose wire causing it to temporarily function.
Yeah I thought that initially, as did the Mech, but again he assured me all wiring, especially that within the Engine bay and going from battery to starter etc, was checked, cleaned etc.

8992



I went on a serious hunt for one of these diagrams so that I could try and figure some of this stuff out for myself and whilst I generally get it, I wanted to ask in the top left diagram which is called "Thirteen Position Auxiliary Relay Panel (Under left side of Dash)", is that referring to the Relay within the 13th Position on the Relay Panel, or just the 13 socket relay panel in general.

I was hoping to establish if that diagram was referring to a specific relay (and if so, which one is it?) or if it was just referring to the relay panel as a whole?

Reason I ask is because on the right side of the diagram where it refers to the "Starting Interlock Relay", it's quite specifically and clearly referring to the "one" thing but when I looked up the relay list (Golf/Jetta IV Relay List), that "one" thing was actually made up of two relays (53/185) which is why I was considering getting replacements for those two. However, I'm still not clear specifically what relay is being referred to in the top left diagram. Anybody any ideas?


In Brief:
Have
:
An ignition Switch;
Considering the following to be sure:
Relays 53, 109 & 185 and a;
Clutch Pedal Position Switch
 

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I went on a serious hunt for one of these diagrams so that I could try and figure some of this stuff out for myself and whilst I generally get it, I wanted to ask in the top left diagram which is called "Thirteen Position Auxiliary Relay Panel (Under left side of Dash)", is that referring to the Relay within the 13th Position on the Relay Panel, or just the 13 socket relay panel in general.

I was hoping to establish if that diagram was referring to a specific relay (and if so, which one is it?) or if it was just referring to the relay panel as a whole?

Warning *** this diagram is from my Bentley Service manual for New Beetle MK4

It looks like they are referring to the top half of this fuse panel as an "auxiliary 13 position relay panel" see attachment
 

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Warning *** this diagram is from my Bentley Service manual for New Beetle MK4

It looks like they are referring to the top half of this fuse panel as an "auxiliary 13 position relay panel" see attachment
Hi,

So basically the whole thing?

I have been driving the car around for a week since I picked it up off the Mech and it has not failed me yet. I have the ignition switch on standby, and I am thinking if it does it again, I will bump the car, get it back home and put the switch in.
 

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Discussion Starter #13
Update for anyone who is interested - still yet to fail since I collected it from the Mech

Side note: passed its annual road safety test-inspection (MOT in UK) on its first attempt.

Like a phoenix from the ashes!
 
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