Service Information for Glow Plug System on '10 VW Golf

Sean Technician Ohio Posted   Latest   Edited  
Resolved
Propulsion
2010 Volkswagen Golf TDI 2.0L (CJAA) 6-spd (02Q) — WVWNM7AJ6AW292701
Extended Crank/Start
Self Test Won't Actuate Module

I am mainly looking for description operation of the glow plug system. I cannot find anything on alldata or identifix. For those curious its an extended crank. self test would not actuate the module. installed new module. all powers and grounds ok, new module the sequential test will run, I have control on the 2 wires going to pcm, and all 4 plugs operate. but cold start there is no control Ive looked at every temp PID I could find all read the same as ambient temp during cold start.

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Sean Diagnostician
United Kingdom
Sean
 

How cold is “cold start” Sean?

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Sean Technician
Ohio
Sean
 

Overnight sit, ilet it set 8 hours during the day temps at around 98*f and it fired right up. Morning at around 65 takes about 10sec

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Sean Technician
Ohio
Sean
 

and that's also why I am asking. because if the system dont even operate at the temps I am at Ive got something else going on. but I cannot find info.

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Sean Diagnostician
United Kingdom
Sean
 

It should start within a few revolutions at that temp without any glow plugs Sean. You have another issue I'd say. Cranking speed high enough? Fuel quality good?

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Sean Technician
Ohio
Sean
 

Speed is the same during extended and not. I am just assuming fuel quality is good, as other than first start, its great, runs awesome and no codes. But ill get a sample in the am.

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Louie Technician
New York
Louie
 

Check for a blown brake light bulb(s). I once had a Jetta with a glow system issue that was corrected by replacing both blown brake light bulbs.

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Sean Technician
Ohio
Sean
 

they are working

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David Mechanic
United Kingdom
David
 

Sean , check YouTube DianoseDan, VW Golf 2.0 TDI long crank. Hope it helps ! Regards Dave T…

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Sean Technician
Ohio
Sean
 

This one is non vvt. Thanks though

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David Mechanic
United Kingdom
David
 

Sean , scope the rail pressure sensor and look for the time it takes to reach starting pressure when cold long crank and compare with when it starts normally . See if it is noticeably different .

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Sean Technician
Ohio
Sean
 

I did actually and I just got to work ill post my captures

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Sean Technician
Ohio
Sean
 

Here is a screen grab of cold ill post more soon

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Harm Technician
Ontario
Harm
 

Had this on older tdi`s where the battery had to be almost perfect or else it would not turn on glow plugs. Just a thought.

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Sean Technician
Ohio
Sean
 

Battery is fully charged

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Sean Technician
Ohio
Sean Update
 

As I have gotten some ideas. This engine is not vvt, timing stays exact same during extended crank vs. regular crank. Usually its about 4.5 to 5 sec crank. when no issue it is a 950ms crank time, fuel pressure builds quickly compared to when it starts quick they reach the same voltages. I also probed the glow plug pressure sensors and all 4 are equal voltages and amplitude. This time I…

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David Mechanic
United Kingdom
David
 

Sean to recap, the time for the rail pressure build up is the same hot and cold ( short crank, long crank ) correct ? The RC test looks even and the amp draw looks about right . A compression test would be a good idea seeing as the glow plugs being operated cure the cold long crank. The scope screen capture you posted has a lot going on and not all the screen is shown , could you have a look…

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Sean Technician
Ohio
Sean Resolution
   

so to recap all. Car came in for extended crank on first start of the day. I have only diagnosed maybe 3 diesels in my 15 years. I know very little (but i know basics). I ran the self test and found glow plugs would not operate, replaced module now self test runs them. they do not operate at these temps, still unsure if thats normal or not as I could not find any info on when and how long. so I…

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