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Coil light flashing !!! Witts end

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URL: http://www.brick-yard.co.uk/forum/forum_posts.asp?TID=93641
Printed Date: 29 Mar 24 at 04:55
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Topic: Coil light flashing !!! Witts end
Posted By: T5 surfer
Subject: Coil light flashing !!! Witts end
Date Posted: 08 Aug 18 at 17:17
Hi guys
Newbie here hope someone can help
T5.1 2013 102

Long story short...
Coil light flashing so fit new egr valve

Coil still flashing.. open circuit in water pump.
Changed both water pumps genuine

Coil now still flashing limp mode

Coil flashes during start up 80% of the time but if i put ignition off while driving and jump start it the coil ligjt will go off.

Also noticed that sometimes the vacum to the egr diagraphram is sometimes up and this gives the coil light flash
Agsin sometimes it will be in the right state and it will still give coil light flash
During coil light flash it will always be limp mode till i put ignition off and bump start it.

Van has a celtic remap and has been fine for about 18months

Any help greatly appreceated as i really am going to throw the towel in...



Replies:
Posted By: T5 TDI
Date Posted: 08 Aug 18 at 23:12
Hi T5,  It's all getting a bit muddled.  Do you have access to VCDS?   If so, clear any codes you have (save them somewhere first). Then drive the van until the coil light is flashing again.  Using VCDS go to 'Autoscan' and it will look through all the various systems on the van for faults.  This will take a few minutes.  Save the scan results and post them here.  

I'm not familiar with the 2.0 CR engines but perhaps you have a fault with the vacuum pump or a split vacuum pipe or even wrongly connected pipes to the new EGR valve.  Did you use a genuine EGR valve?     


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2004 2.5 174


Posted By: T5 surfer
Date Posted: 08 Aug 18 at 23:51
Thanks for the reply
Just been on the vcds now and its again showing coolant pump 2 open circuit fault.
Ive had a new pump fitted genuine vw and also had the wiring checked and that was ok.
Im thinking maybe its a relay fault.

Where is the coolant pump 2 relay? Anyone know?


Posted By: T5 TDI
Date Posted: 09 Aug 18 at 09:18
I've read a post by Matertech where he says the wiring can chafe and short near the starter motor.  Have a really close look at the loom especially if it is touching the starter.  Sometimes just a small rub mark on the outside of a loom is all it takes for a short.  Your code says 'open circuit' not 'short' but that can be caused if the fuse blows as the result of a short, so check all of the fuses, including under the bonnet by the battery where you should also find the relay (if it has one). 




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Posted By: T5 surfer
Date Posted: 09 Aug 18 at 09:48
Ive had all the wiring checked and all is ok, the mechanic knew about the wiring chaffing over the starter so checked it all they way back to the ecu.
The fuse is ok and i ran the coolant pump under vcds and it ran with no problems
The fault is intermittent that makes it really hard to find
Im thinking now if there is a rellay somewhere for it?


Posted By: T5 TDI
Date Posted: 09 Aug 18 at 10:53
If there is a relay it should be under the fuse box under the bonnet.  Have you seen this? https://www.vwt4forum.co.uk/showthread.php?t=1514081" rel="nofollow - https://www.vwt4forum.co.uk/showthread.php?t=1514081

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2004 2.5 174


Posted By: T5 surfer
Date Posted: 09 Aug 18 at 16:08
Yes had a good read through that post and checked my wires
But i think would be a good idea to check them again


Posted By: AndyT
Date Posted: 09 Aug 18 at 22:19
If there are no performance issues, just pull the bulb.
That way you can take all the time you need to diagnose.


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LT28 1979 2.0 Pampas Nevada Camper LPG 93K, 1980 T3 A/C Camper 98K,1994 RRC 3.9 LPG 120k , 1998 Audi A6 Est 2.5 V6 diesel 127k



Posted By: gregozedobe
Date Posted: 10 Aug 18 at 00:01
Here's a completely left field suggestion:

Could it be your brake light switch ?  These are a common problem with VWs and can cause lots of weird errors.  Check your brake lights come on when they should and go off when they should.  If in doubt, replace (IIRC They are not very expensive).


Posted By: T5 TDI
Date Posted: 10 Aug 18 at 09:09
If you have VCDS you can check the brake light switch in the engine controller by going to measuring blocks (live data) and looking at the cruise control functions.  You should find the brake pedal monitoring there.

Andy- You can't pull a dash bulb these days- All soldered in LEDs!  That won't cure the limp home, only fixing the fault will do that.    


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Posted By: T5 surfer
Date Posted: 10 Aug 18 at 11:46
Thanks for the help guys
Ive plugged in vcds and its still the same fault,
Coolant pump 2 open circuit.
Ive checked brake lights all work ok

Anyone know where the relay is for the coolant pump 2


Posted By: T5 TDI
Date Posted: 10 Aug 18 at 12:59
Originally posted by T5 TDI T5 TDI wrote:

If there is a relay it should be under the fuse box under the bonnet.  


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2004 2.5 174


Posted By: AndyT
Date Posted: 10 Aug 18 at 13:18
Is this any good?. Relays are 7.2 and 8.1 at the bottom if you can't read the text.

7.2 Additional coolant pump relay -J496- (449)
8.1 Coolant shut-off valve relay -J541- (449)




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LT28 1979 2.0 Pampas Nevada Camper LPG 93K, 1980 T3 A/C Camper 98K,1994 RRC 3.9 LPG 120k , 1998 Audi A6 Est 2.5 V6 diesel 127k



Posted By: T5 surfer
Date Posted: 13 Aug 18 at 00:13
Hi matey
that's absolutely perfect just what I was looking forClap
im unable to zoom on the picture though
have you got a larger image Smile
 
I cant quite make it out, are they in the engine bay under the battery?


Posted By: AndyT
Date Posted: 13 Aug 18 at 01:32
Just says in the engine bay.
Had to shrink the image to be able to post it and didn't keep the original, but....

If you find the plate with the vin, engine & gearbox codes, take a pic and email me (in profile).
I can then do an exact search in elsawin, and send the results back to you.


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LT28 1979 2.0 Pampas Nevada Camper LPG 93K, 1980 T3 A/C Camper 98K,1994 RRC 3.9 LPG 120k , 1998 Audi A6 Est 2.5 V6 diesel 127k



Posted By: T5 TDI
Date Posted: 13 Aug 18 at 10:47
Originally posted by T5 surfer T5 surfer wrote:

 
I cant quite make it out, are they in the engine bay under the battery?

Yes I think they are in the E-box under the battery.


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2004 2.5 174


Posted By: Paul18765
Date Posted: 14 Jun 19 at 21:22
Hi, did you ever get to the bottom of this, I’ve got exactly the same problem.


Posted By: gregozedobe
Date Posted: 15 Jun 19 at 02:27
Originally posted by Paul18765 Paul18765 wrote:

Hi, did you ever get to the bottom of this, I’ve got exactly the same problem.

Could be a DPF problem ?
 

T5 surfer hasn't been on here for ages, so I don't think you'll get a reply from them:
Last Visit:08 Sep 18 at 19:20


Posted By: Paul18765
Date Posted: 15 Jun 19 at 07:29
Wouldn’t that be shown with the dpf warning light? Why would the coolant pump error code show?


Posted By: gregozedobe
Date Posted: 15 Jun 19 at 12:23
A friend ran over a wombat which took out a DPF sensor, he tells me the "coil light" came on (and limp mode if he's remembering correctly - it was a few years ago).

VW's can show all sorts of weird (and un-related) error codes when things go wrong.  Worst is if the voltage regulator allows too high a voltage, everything goes crazy.

Diagnosing vehicle problems on-line is a very imprecise science, and even more so when you are getting free advice from random internet denizens .....


Posted By: T5 TDI
Date Posted: 15 Jun 19 at 19:02
You don't say what van you have Paul, there are huge differences that can make a perfectly good reply for one van meaningless for another.  If your van is an early one it will have no engine management light so the glow plug light doubles for it.  You need to get a full scan of everything on the van (not just the engine fault codes) as a good start point.  Something as simple and cheap as a brake light switch can cause the glow plug light to come on for instance.  

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2004 2.5 174


Posted By: Paul18765
Date Posted: 15 Jun 19 at 19:08
Hi, it’s a 2011 2l diesel, CAA engine . Done a full scan, no other codes.


Posted By: Paul18765
Date Posted: 15 Jun 19 at 19:10
Just the same original p261a00 coolant pump b open circuit.


Posted By: T5 TDI
Date Posted: 15 Jun 19 at 21:12
When the pumps fail they can leak into the electrics.  You may have fixed the problem with the new pump but if it blew the fuse as well, that could be what it is.  That one will probably be one of the fuses down by the battery.  

The pump has a connection to the ECU so make sure you know what you are probing when testing around the wires.  The ECU itself could cause it but better to find a wiring diagram and confirm that the wiring is ok before spending any big money.  As far as I know the ECU controls the pump and can switch it on for several reasons ie if the engine needs extra cooling in summer (I only ever hear mine on a few boiling hot days in August when I already have the A/C on).  To cool the EGR valve and to even the cooling of the head after switch off to prevent any hot spots although I have never heard mine do this.  

You probably won't hear your pump like I can on my old '04 on the rare times it comes on.  Later vans had the pump isolated on a piece of rubber.        


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2004 2.5 174


Posted By: Paul18765
Date Posted: 15 Jun 19 at 21:19
Thanks for the reply. I’ve been having another go today. I’ve checked the loom, again, all good, checked the connections and wiring through to the ecu, all good. Ran vcds again, cleared the fault code, test ran the pump through vcds, confirmed it works, again, all good. No “new” warning as yet. Just a bit concerned that I haven’t actually found a problem as yet.


Posted By: T5 TDI
Date Posted: 15 Jun 19 at 22:05
Fingers crossed then! Smile

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2004 2.5 174


Posted By: T5 surfer
Date Posted: 20 Jun 19 at 11:25
Hi guys im sorry for not getting back sooner
Been without the t5 for a while
But back in it now and problem still persists

So same as before but a bit more info

Van goes into limp mode while driving

Only comes on during starting the van intermittent
Resets if i jump start in van while driving. Ie ignition off, ignition on and lift clutch in gear.

Also after 3 times the eml comes on but will reset on the 3rd trio of driving then fault wont come until maybe a few weeks again its its  intermittent.

Never happens while driving only strarting.



Posted By: gregozedobe
Date Posted: 21 Jun 19 at 08:10
I hate intermittent problems, they're such a pain to diagnose and fix :(


Posted By: T5 surfer
Date Posted: 23 Jun 19 at 12:53
Does the pump run all the time?

Thinking of running another supply to the oump to see if that cures the fault.


Posted By: Paul18765
Date Posted: 23 Jun 19 at 12:58
Hi All, thanks for the replies, just a quick update. May have cured it..... after talking to a few mechanics I was advised to ditch the after market pump and replace it with a genuine VW one, leave it disconnected, clear the fault code and reconnect. Done all that and haven’t seen a warning light since!!!!


Posted By: T5 surfer
Date Posted: 29 Jun 19 at 10:36
Ah ok, mine was a pierburg but still had faults and i changed it to a genuine vw one and im still getting the fault open circuit.

So if i dissconect, clear faults and reconnect that should work

Ill try that 


Posted By: T5 TDI
Date Posted: 29 Jun 19 at 19:07
Originally posted by Paul18765 Paul18765 wrote:

I was advised to ditch the after market pump and replace it with a genuine VW one, leave it disconnected, clear the fault code and reconnect. Done all that and haven’t seen a warning light since!!!!

That's odd.  Normally pulling wires off things causes an open circuit code.  It should come straight back if you clear it with the wires off. Confused  


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2004 2.5 174


Posted By: Paul18765
Date Posted: 29 Jun 19 at 19:29
That’s what I though, however I followed the guys instructions and sure enough, it worked..... at least for a few hundred miles. It’s since poppped up a couple of times, immediately gone off and not reappeared for another coupe of hundred miles. I’m currently in Slovenia, having driven from Rotterdam, not a single flash...... again, fingers crossed.


Posted By: T5 surfer
Date Posted: 04 Jul 19 at 13:36
im beggining to winder now if this is anything to do with my remap?

I would like to know if the pump is on permanent as i could add another live to it, just to prove the pump is working and rule out any connection problems.

How do i gain access to the ecu? And to the wiring of the pump over the starter motor? 


Posted By: Paul18765
Date Posted: 04 Jul 19 at 23:32
Hi, the pump is not wired to run permanently, it’ll run when the ecu calls for it only, usually when it’s really hot and the engine is turned off.


Posted By: T5 TDI
Date Posted: 05 Jul 19 at 12:19
I'm with Paul Thumbs Up except for that I know my pump can run when the engine is running.  The reason I know this is that in around '05, a Workshop Campaign was issued for for customers who complained of noisy secondary coolant pumps.  The fix was fairly basic, just a small rubber strip to isolate the pump from the body.  I never bothered with mine because I quite like to know it if it comes on.  I have only ever heard it come on briefly on very hot days, in traffic, when maybe a little extra cooling is needed.

I wouldn't add current to any part of the pump whilst it's connected unless you have a wiring diagram. If you make a mistake you could wreck the ECU.  Bear in mind that sometimes the ECU provides an earth rather than a live feed to switch a component and that the pump may have a ignition switched 12v supply too and/or even a 5v reference voltage which is another reason to be very careful probing/shorting/powering anything without being absolutely certain what it is.

The ECU is under the battery by the E-box (which is a big junction of connectors) you might have to take the E-box lid off, I can't remember.

Mine is an '04 so the design might change over the years. 


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2004 2.5 174


Posted By: T5 surfer
Date Posted: 06 Jul 19 at 21:10
thanks, a very good point indeed, not just a simple on off circuit then, i will refrain from any wiring modifications.


Posted By: T5 TDI
Date Posted: 06 Jul 19 at 22:21
It certainly is an odd one.  (Or two since you both have similar problems) I wouldn't have thought that any genuine fault with the secondary coolant pump would have led to a engine management light being on.  Half of the pumps on older model vans have fallen to bits long ago and aren't working. The first thing most people know is when they notice coolant drips underneath or someone else working on the van spots corroded wires hanging down.  

I haven't had much to do with the new model but I know EGR problems have been very common.  I wonder if the secondary coolant pump feeds the EGR cooler on the CR engined models.  From pics I have seen online, the electrical part of the EGR valve gets badly corroded with these EGR failures and this could lead to the EML light coming on and limp home if the ECU gets mixed messages from the corroded wiring.  If you haven't already had a new EGR valve, read all the (endless!) threads on them via google and be sure yours is working properly.  Smile




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2004 2.5 174


Posted By: Paul18765
Date Posted: 06 Jul 19 at 23:27
Thanks again, yes will do. I’m driving home in a couple of days, Dubrovnik to uk, about 1200 miles, over 4 days, we’ll see what happens, I’ll do a bit more work on it , if/when I get it home. I’ll keep you posted.


Posted By: T5 TDI
Date Posted: 07 Jul 19 at 09:23
Have a good journey! Smile   I was thinking of doing a big European trip with mine last month, but some recent serious health issues have put that on the back burner for now.  I'm quite glad now I didn't go because I would have ended up in French hospital in a big heat wave.

You could try making a few VCDS logs while you are a captive in the cab. If the limp home happens while it's hooked up you might be able to work out the cause.  If you do fancy having a go, make sure to get EGR, boost, RPM, and throttle opening (load shown in percent) logged together.   


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2004 2.5 174


Posted By: Paul18765
Date Posted: 07 Jul 19 at 10:10
Thanks I will.


Posted By: T5 surfer
Date Posted: 11 Jul 19 at 10:10
good point about the.  Egr
And i do believe the pump feeds the egr valve cooler also.
This is what came up on my faults first so i replaced the egr valve and had it coded in so thats all good hopefully.

Now i was thinking as you do...
So the fault only comes up during start up

So im im thing that when you switch off the pump is meant to come on to cool, now i think the fault is that the pump isnt kicking in,
So when i start the engine again it throws up the coil light as the pump didnt start on last start up.

Pump does work though if i use vagcom to switch it on

Another thing i have found is when using the torque app or car scanner pro app.

This is reading my coolant temp and its shockingly high
120 degC to 147 degC
But no warning lights on dash and no temp gauge either.

My mechanic asked which coolant sensor was ir reading but i had no idea.

So looks like the temp is high, the pump should cut in but isnt
The pump should cut in when i switch off but isnt 
And this maybe whats giving me the coil light.

I want to check the wiring from pump to the ecu but how do i gain access, i cant see much from underneath 🤔


Posted By: T5 TDI
Date Posted: 11 Jul 19 at 11:25
You could definitely do with being sure about the coolant temp sensor.  That won't be a genuine reading because the engine would be boiling but it could be that the coolant sensor is failing and sending the wrong value to the ECU.  However normally a value that high would cause a code.  The other possibility is that the scanners are mis-labelled and that reading is for another temp (exhaust gas maybe).  Although it seems odd if you have tried two different scanners.

You ought to get to the bottom of that before you go much further.  If you can find someone with genuine version of VCDS it would be easier, it is very reliable.  The sensor you are looking for is called the G62 coolant sensor.  There may be more than one.  


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2004 2.5 174


Posted By: T5 surfer
Date Posted: 26 Jul 19 at 23:08
where are the coolant temp sensors on the t5.1 2013 102bhp?
I think i will change them to be sure

Today i stripped all the wiring but found no damage, also did a continuity test all ok
So i guess ill try the sensors



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