testing glow plugs

[passat 130 tdi]

i have ordered myself a multi meter and im going to check the glow plugs , just to see if maybe they are the reason my car dont run properly , can someone tell me if a good plug has zero ohm resistance or should it have a value , do i need the ignition on when checking or leave it off ??


thanks in advance ...

[smithy602179]

i dont think you get a reading when they are duff , i just replaced all of mine from tps for 32 quid for a set of 4 .

[zollaf]

running or starting. glow plugs help with starting but once it is running they switch off so don't help.

[passat 130 tdi]

running or starting. glow plugs help with starting but once it is running they switch off so don't help.

runs as if on 2 pots only,for about 10 seconds, if i disconnect the temp sensor and it starts fine and runs fine. i just want to dismiss the glow plugs from my findings to this problem..... i know the role of a glow plug , just need advice on testing them with a multimeter.

[zollaf]

testing with a multimeter isn't always conclusive so i remove them and connect direct to a battery to observe the heating of the tip.

[S66MJETDI]

runs as if on 2 pots only,for about 10 seconds, if i disconnect the temp sensor and it starts fine and runs fine. i just want to dismiss the glow plugs from my findings to this problem..... i know the role of a glow plug , just need advice on testing them with a multimeter.

Hmmm I think you may have found your issue then! Coolant temp sensor would be my culprit. Have you run a scan, the glow plugs show up on VCDS if they are kaput.

[passat 130 tdi]

Hmmm I think you may have found your issue then! Coolant temp sensor would be my culprit. Have you run a scan, the glow plugs show up on VCDS if they are kaput.

its all listed in my " conking out on start up " thread m8 .... sensor was changed .... all i see on vcds on plugs is zeros and all 1's when they are off , is there another glow plug section within vcds i dont know about - thanks

[martin1810]

00000000 means no glow as waiting for coolant temp signal.
11111111 means glow cycle complete.

You need to watch the start up cycle to see what other values appear.
01110000 should mean ready to start.

Measuring glow plug resistance is hard because it should be just above Zero. About 1 or 2 ohms. The best method is to borrow a clamp amp meter from someone. That will show how much current each plug is pulling. Your fault does sound like a couple of glow plugs are not working. They don't only work to start the engine, they often glow a little after engine start.

[passat 130 tdi]

00000000 means no glow as waiting for coolant temp signal.
11111111 means glow cycle complete.

You need to watch the start up cycle to see what other values appear.
01110000 should mean ready to start.

Measuring glow plug resistance is hard because it should be just above Zero. About 1 or 2 ohms. The best method is to borrow a clamp amp meter from someone. That will show how much current each plug is pulling. Your fault does sound like a couple of glow plugs are not working. They don't only work to start the engine, they often glow a little after engine start.

thanks martin, finally getting somewhere , im getting 01010000 - whats this saying then ????

i will take another reading in the morning cos the temp was 49 degrees , 01010000 means no pre glow required apparently .

[passat 130 tdi]

i get 0101000 and 0.00 in the glow time box everytime hot or cold , if i set the 32768 i think it is default to 32700 it does start better and it did log a 8.6 sec glow time

[martin1810]

Do you ever see any of these?
Glow Plug activation sequence

00000000 = Waiting for Coolant Temperature
00000001 = Waiting for ECO Start Request
00010000 = Pre-Glow
01010000 = No Pre-Glow
10110000 = Post-Glow
11000000 = No Post-Glow
11110000 = Interim Glow
00110000 = Readiness Glow
01110000 = Start Glow
10110001 = Waiting for Post-Glow
11010000 = No Post-Glow
11110001 = Waiting for Interim Glow
11111111 = Glow OFF

They wont all show but I would expect to see some of them.
I still think you should replace the glowplugs first as a couple of faulty ones may be the problem.

[passat 130 tdi]

thanks martin ,, i only see 0101000 before start up then 1111111, never ever seen any other numbers .. anyways the sparky at work loaned me his amp clamp , strapped it onto the battery lives and with ignition on it grabbed 8.6 amps , so im guessing 3 are fuubarred .... if i preheat at least 4 times it starts no bother , so i have oredered a set of 4 lucas plugs £ 25 , will report back when they are fitted ....

[passat 130 tdi]

changed all 4 just now, tested the old ones and 2 are foobarred . i'll find out better in the morning when engines cold as to weather or not its cured the bad start issue - vagcom still gave me 01010000 , but engine was canny hot still ....

[smithy602179]

if temperature is above 5' the plugs wont preheat i believe , i think if you disconnect temp sensor it will fool car into using preheat , i'm sure crasher or martin will confirm or deny this as they are more experienced than me .

[passat 130 tdi]

after changing all the glow plugs , my problem still exists , think im just gonna leave the temp sensor off as i only start the car twice a day anyhow , either that or find which wires control the temp guage on the dash and cut the others that are sending signals to the ecu ....4 new glow plugs and a new temp sensor and its till a bitch to start ...

[PCDoctor]

Hi Passat 130

Can you get hold of that current metre and measure again

Each glow plug is approx 15 amps each (60 amps) plus starter motor

So you should see massive current use from start on a cold engine from the battery lead....

I Had siilar issue recently with difficult start but cured now with NEW uprated battery .... turns over in a second hot or cold...

Where about are you in the country..

[passat 130 tdi]

Hi Passat 130

Can you get hold of that current metre and measure again

Each glow plug is approx 15 amps each (60 amps) plus starter motor

So you should see massive current use from start on a cold engine from the battery lead....

I Had siilar issue recently with difficult start but cured now with NEW uprated battery .... turns over in a second hot or cold...

Where about are you in the country..

i wont see any curent use unless the ecu supplies one at start . theres a definate fault of an electrical kind somewhere. £ 120 new battery went on 4 weeks ago. unplug temp sensor and it fires 1st time every time...

[martin1810]

It looks like you have a wiring fault between the coolant temp sensor and the ecu. You need to check all the connectors and wires carefully especially at the ecu. Have you tried using vag-com to measure the coolant temperature from cold and as engine warms up?

[passat 130 tdi]

It looks like you have a wiring fault between the coolant temp sensor and the ecu. You need to check all the connectors and wires carefully especially at the ecu. Have you tried using vag-com to measure the coolant temperature from cold and as engine warms up?

i have watched it rise as the engine heats up..... i have to turn the engine over 3 times for it to run ok, mind i only need to just turn the key, it always started in an instant though. now it rumbles for 8 seconds or so as if on 2 cylinders then the revs jump up to 950 ish ... 4 or 5 heats makes no difference at all. do you know which of the 4 wires talk to the ecu on the CTS plug ..???? I'd also be interested in the timing of tdc on vagcom , i remember seeing 39 degrees on 1 screen and 5.6 degrees on another in measuring blocks. i m having the timing belt and pump changed next week so the timing should be spot on with a new belt .. the car runs rings around bmw's once its warmed up so there's not that much wrong with her.

[martin1810]

I don't have all the details for your car but with luck, these are the wires.
Temp sensor - display Blue/Brown & Brown/Yellow.
Temp sensor - ECU Brown/White & Brown/Grey.

The simplest test is to disconnect wires at both ends and substitute some other good wire. Depends how you feel about playing with electrics. An ohm meter will give a continuity result but a an extra battery and a bulb are better. If in doubt, don't do anything because damaging the ecu is costly.

[passat 130 tdi]

I don't have all the details for your car but with luck, these are the wires.
Temp sensor - display Blue/Brown & Brown/Yellow.
Temp sensor - ECU Brown/White & Brown/Grey.

The simplest test is to disconnect wires at both ends and substitute some other good wire. Depends how you feel about playing with electrics. An ohm meter will give a continuity result but a an extra battery and a bulb are better. If in doubt, don't do anything because damaging the ecu is costly.

update - just been out and with sensor plugged in all 4 glow plugs were showing 11.4 odd volts , i then tested the pins on the multi plug and pins 1 and 2 read a voltage , pins 2 and 4 read zero , if thats signifigant or not i dont know ??? maybe the pins 2 and 4 may show when connected to the sensor i presume ...

im going to check the torsion value and injectors with vagcom later today , just read up on that via a martin link ...

[martin1810]

update - just been out and with sensor plugged in all 4 glow plugs were showing 11.4 odd volts , i then tested the pins on the multi plug and pins 1 and 2 read a voltage , pins 2 and 4 read zero , if thats signifigant or not i dont know ??? maybe the pins 2 and 4 may show when connected to the sensor i presume ...

im going to check the torsion value and injectors with vagcom later today , just read up on that via a martin link ...

I don't recal the pin numbers but the voltage is correct. Two pins should have volts and two shouldn't. One pin for temp gauge and one pin for ecu. I assume either the ecu to sensor or sensor to ecu wire is faulty, damaged as it sounds like your glowplugs are not switching on correctly.

[passat 130 tdi]

I don't recal the pin numbers but the voltage is correct. Two pins should have volts and two shouldn't. One pin for temp gauge and one pin for ecu. I assume either the ecu to sensor or sensor to ecu wire is faulty, damaged as it sounds like your glowplugs are not switching on correctly.

DO you think it could be fuelling/timing issue , as i tested each plug with the coolant sensor connected and each plug showed good voltage .....

[martin1810]

I doubt it's a fuel or timing problem although it's possible. The glowplugs not being switched correctly is far more likely. They are not simply switched on or off. They are under ecu control and the ecu needs the coolant signal to base its calculations. I think a damaged wire or connector is the most likely.

[andwat]

Wouldnt imagine this is glow plug related...The TDI only needs glow plug input in really cold weather and even then car will always start pretty quickly. I had exact same issue on 2005 1.9TDI Touran...car started, then died then took ages to restart again. I was months trying to get to bottom of it, tried starter motor, battery, fuel pump, temp sensors, glow plug control module...then eventually figured it was a leaking injector seal - you can buy a set for around £30.00 for the 4 injectors. Not sure which one was leaking but this was causing diesel to leak back to tank and loss of vacumn. Hope this helps!

[passat 130 tdi]

Wouldnt imagine this is glow plug related...The TDI only needs glow plug input in really cold weather and even then car will always start pretty quickly. I had exact same issue on 2005 1.9TDI Touran...car started, then died then took ages to restart again. I was months trying to get to bottom of it, tried starter motor, battery, fuel pump, temp sensors, glow plug control module...then eventually figured it was a leaking injector seal - you can buy a set for around £30.00 for the 4 injectors. Not sure which one was leaking but this was causing diesel to leak back to tank and loss of vacumn. Hope this helps!

interesting theory, but it doesnt explain why my car starts instantly on a morning if i remove the ect sensor ... it only doesnt start immediately when the sensor is connected....

[scotty33]

Have you looked at the coolant temp with VCDS, it is the signal to the ECU you are looking at. If there is a wiring/connector plug fault to the extent that it affects starting, it won't look right on a log?

[passat 130 tdi]

point me in the right direction and i;ll have a look ....

[passat 130 tdi]

i upped the glow time using vcds lite , car starts a lot better now, but im still thinking its to do with fuelling and the fact that ive extended the glow time means that fuel is now entering the chambers while the glow is still there. or I could be also talking pap .... but hey ho its a go go go most times now ...

[scotty33]

point me in the right direction and i;ll have a look ....

Courtesy of Martin1810 and his excellent site!

VCDS AND PD TDI ENGINE HEALTH CHECK - PASSAT (https://sites.google.com/site/1810martin/vcds-and-pd-tdi-engine-health-check)

VCDS DATA LOG ENGINE - PASSAT (https://sites.google.com/site/1810martin/vcds-data-log)

HOW TO TURN A VCDS LOG INTO AN EXCEL GRAPH. - PASSAT (https://sites.google.com/site/1810martin/how-to-turn-a-vcds-log-into-an-excel-graph)

[passat 130 tdi]

vcds states 76.5 degrees , dash states 90 ...... is this a thermostat issue lads ??????? I also logged a file , cant get it to turn into excel graph ....

[scotty33]

I've had thermostat issues with both of mine, highest VCDS temp was about 74-75 deg C with the gauge showing slightly less than 90 (less than a needle width). It does make them thirsty, but would not give a starting issue. I was more concerned about what the cold coolant temp, should be ambient or thereabouts?

[passat 130 tdi]

I've had thermostat issues with both of mine, highest VCDS temp was about 74-75 deg C with the gauge showing slightly less than 90 (less than a needle width). It does make them thirsty, but would not give a starting issue. I was more concerned about what the cold coolant temp, should be ambient or thereabouts?



Fuel Temp
Fuel cooling state
Intake Air Temp
Coolant Temp


~Amb.Temp.*C
On:100%-Off:0%
~Amb.Temp.*C
~Amb.Temp.*C


°C
%
°C
°C



10.8
0
12.6
13.5

[martin1810]

Can you post the measuring block (007 I think) that has the coolant, fuel and air temps. You need to get a reading when the engine is cold and another when it is fully warmed.

[passat 130 tdi]

Can you post the measuring block (007 I think) that has the coolant, fuel and air temps. You need to get a reading when the engine is cold and another when it is fully warmed. those figures above martin , are the start of my journey , here's the last few rows of a 20 minutes trip ..


55.8
0
25.2
76.5



55.8
0
25.2
76.5



55.8
0
24.3
76.5



55.8
0
24.3
76.5



55.8
0
24.3
76.5



55.8
0
24.3
76.5



55.8
0
24.3
76.5



55.8
0
24.3
76.5



55.8
0
24.3
76.5



55.8
0
24.3
76.5



55.8
0
24.3
76.5



55.8
0
24.3
76.5



55.8
0
24.3
76.5



55.8
0
25.2
76.5



55.8
0
25.2
76.5



55.8
0
25.2
76.5



55.8
0
25.2
76.5



55.8
0
25.2
75.6



55.8
0
25.2
75.6



55.8
0
25.2
75.6



55.8
0
25.2
75.6



55.8
0
25.2
75.6



55.8
0
26.1
75.6



55.8
0
26.1
75.6



56.7
0
25.2
75.6



56.7
0
25.2
75.6



56.7
0
26.1
75.6



56.7
0
26.1
75.6



56.7
0
26.1
75.6



56.7
0
26.1
75.6



56.7
0
26.1
75.6



56.7
0
26.1
75.6



56.7
0
26.1
75.6



56.7
0
26.1
75.6



56.7
0
26.1
75.6



56.7
0
26.1
75.6



56.7
0
26.1
75.6

[martin1810]

The temps are difficult to evaluate because I don't know what the figures were like where you live. The last few days in Norfolk we have had near 0 C temps over night so coolant temp wouldn't be 13.5 C at start up. Perhaps it's warmer where you live. The end journey coolant temps are wrong. They are too low. At 75 C you will probably be running on the wrong injection map and using extra fuel. I still think you should check and clean the coolant sensor connectors and the ecu connector but you probably need a new thermostat. Thermostat won't help the starting though.

[passat 130 tdi]

The temps are difficult to evaluate because I don't know what the figures were like where you live. The last few days in Norfolk we have had near 0 C temps over night so coolant temp wouldn't be 13.5 C at start up. Perhaps it's warmer where you live. The end journey coolant temps are wrong. They are too low. At 75 C you will probably be running on the wrong injection map and using extra fuel. I still think you should check and clean the coolant sensor connectors and the ecu connector but you probably need a new thermostat. Thermostat won't help the starting though. I know the stat wont help starting , but its something I noticed that's all to be not right ... today things took a turn for the worst , the car now simply refuses to start as if no fuel at all is getting in , and when it finally does fire even when hot , the idle is all over the place , the boost is a bit slow also coming on as if its waiting for fuel also .... no fault codes ,I was going to change the fuel filter,, and it will only fire up when I remove the ect sensor ---- Im giving up on the diy approach and im taking it to a mechanic next week , I cant see him wanting to change the timing belt etc when its running like a bag of shyte ..... fed up now !!!!!!!!!!!!,

[scotty33]

Can a sticky dual mass flywheel affect starting?

Passat 130 tdi, have you read fault codes, now it is not starting?

[passat 130 tdi]

I hope this is my problem .... and no I wont be going anywhere until its changed ... video 3 is today , the other 2 were 2 weeks ago when my problem began....
http://smg.photobucket.com/user/maleborn1967/media/VIDEO0010_zps3a4ddcc8.mp4.html
http://smg.photobucket.com/user/maleborn1967/media/VIDEO0011_zpsb64d5577.mp4.html
http://smg.photobucket.com/user/maleborn1967/media/VIDEO0012_zps4c72302f.mp4.html I could hear it slapping against the covers today , so just thought i'd have a look inside..... im thinking the pump timing on start up is out and once running the ecu is correcting the timing .. ??? or am I wrong ?????

[smithy602179]

you may find that changing the belt and a new tensioner may cure your problems if the belt is as loose as it is in the videos , it may have jumped a cog or two did it start giving you trouble after giving it some hard acceleration from a junction by any chance ??????

[passat 130 tdi]

you may find that changing the belt and a new tensioner may cure your problems if the belt is as loose as it is in the videos , it may have jumped a cog or two did it start giving you trouble after giving it some hard acceleration from a junction by any chance ?????? no idea exactly when it happened or whats caused it tbh .... its always been drivin hard since the remap , its at the garage now getting done.... lad says don't be surprised if a tooth or two have sheared off the belt..... as long it gets sorted and boy am I glad I spotted it before it snapped ....

[passat 130 tdi]

had the motor stripped down today by a local mech , turns out the roller bearing that sits under the main belt tensioner has collapsed and the belts tension was lost, thus putting the pump timing a mile out , looking to get a new roller bearing in the morning and hopefully have the car back to its old self.... hopefully being the word at the moment...

[passat 130 tdi]

well new timing belt and water pump all tensioners including the small tensioner behind the cover , changed , timing in the correct place now as it was out from the last garage that changed the belt when I 1st bought the car , and all I can say is WOW !!!!! ... super quick now , a lot quieter , boost comes in sooner , starts 1st time and ticks over like a new car... excellent job £315 all in ..... looks like my audi a6 is on hold for year or two now ... thanks to all who contributed during the non starting problems I had... it just goes to show how important the pump timing has to be for the pd engine to fire up .... the damper tensioner had failed causing the belt to run slack ...

[PCDoctor]

Good job and well done

The disconnecting the temp sensor was a red herring by the look of it..

I Have white smoke on start up from cold well under 10 to 12 degrees and all glow plugs changed and voltages correct as well as VCD reporting no problems

I Do notice from cold the sync angle changes from 1.5 to 0 when she is all warmed up

I May have to go down this route you have taken

[passat 130 tdi]

indeed matey , taking the temp sender off was simply forcing the glow plugs to glow ,which was enough to get it to fire up . once running the ecu was correcting the fuel timing the best it could. well that's my theory anyways .... I also found changing the glow plug glow time using vcds helped a lot also , maybe you might want to give that a try ...

[caldirun]

well new timing belt and water pump all tensioners including the small tensioner behind the cover , changed , timing in the correct place now as it was out from the last garage that changed the belt when I 1st bought the car , and all I can say is WOW !!!!! ... super quick now , a lot quieter , boost comes in sooner , starts 1st time and ticks over like a new car... excellent job £315 all in ..... looks like my audi a6 is on hold for year or two now ... thanks to all who contributed during the non starting problems I had... it just goes to show how important the pump timing has to be for the pd engine to fire up .... the damper tensioner had failed causing the belt to run slack ...

There is no pump timing on the PD engine, it was the camshaft/injector timing that had changed.

[passat 130 tdi]

same thing in theory ,just a different set up . don't be pedantic.

[caldirun]

i wouldn't know, +1 to you , i just diagnosed and for 2 weeks a problem that i finally sorted out . thanks anyways for your massive input.

I would say that the garage that you paid £300+ to diagnosed and sorted your problem, I was just correcting your statement re the pump timing on a PD engine to avoid misleading others, sorry if I upset you!

[passat 130 tdi]

feel free to post your theories .