P0684

[Mo_baig20]

P0684

Hi
I have had this fault come up and an engine light when I start the van on a cold morning. It clears and doesn’t come back until it’s another cold start in the morning. I have had all 4 glow plugs replaced and also the glow plug module. Still the same engine light and p0684.

Anyone know of what it could be?

Thanks

 

[mmi]

I have a MAN TGE 177bhp Fwd biturbo 2020 DAVA engine.

A T6, or a MAN?



I would expect that the ECU still is quite similar to T6/T6.1, so
Does the glow plug controller communicate with ECU at all? You could verify the following

- What does the ECU's built-in test (under Basic Settings) "Test of automatic glow time control module" report?​

- What does the ECU report for "Glow status"?​

- What does the ECU report for "Preheat time"?​

​

Do the glow plugs actually heat-up? Can be verifed either actually measuring they get voltage/current or taking advantage of "Battery monitor Control Module" under 19-CAN Gateway (on MAN) or dedicated "61-Battery Monitor" on T6.

Examples of diagnostic tool measurements below

Post in thread 'Intermittent starting issue'

21 Mar 2023

However, I am curious as to why "IDE00412 Starter control: terminal 50" remains "active" in the above known good start, but is "not active" during cranking in skahigh's original no start data, shown in Dellmassive's post #12 - except for one line, presumably when the key was turned to start position?

My assumption is IDE00412 is indeed only a recording of the key in start position. In the snippet below the key was very briefly flipped into start position - just to catch the timing of events following it.

There are quite a number of parameters available - unfortunately only 12 can...

• mmi

• 
• 

Post in thread 'Which Jump Starter?'

21 Oct 2018

And off course jump starting.... now needed it on our vans yet.... but used numerous times to help out others.

So that's in the real world. But in theory?

T6 diesel engine start-up

Measurements were done using a VCDS cable, achieved time resolution 130 ms.​

Timeline of events :

• Timestamp 3.5 sec: Initiate starting by turning key to position start
  
  Preglow, power up of ECU+other modules, lights, etc​
• Timestamp 5.2 – 6.0 sec Engine cranking, drain from battery peaks at 400 A for 0.3 sec
  
  Afterglow​
  ...

• mmi

• 

 

[manfrotto]

Did you check the relay / fuse for the glow plugs as well

 

[Mo_baig20]

A T6, or a MAN?

View attachment 305314

I would expect that the ECU still is quite similar to T6/T6.1, so
Does the glow plug controller communicate with ECU at all? You could verify the following

- What does the ECU's built-in test (under Basic Settings) "Test of automatic glow time control module" report?​

- What does the ECU report for "Glow status"?​

- What does the ECU report for "Preheat time"?​

​

Do the glow plugs actually heat-up? Can be verifed either actually measuring they get voltage/current or taking advantage of "Battery monitor Control Module" under 19-CAN Gateway (on MAN) or dedicated "61-Battery Monitor" on T6.

Examples of diagnostic tool measurements below

Post in thread 'Intermittent starting issue'

21 Mar 2023

However, I am curious as to why "IDE00412 Starter control: terminal 50" remains "active" in the above known good start, but is "not active" during cranking in skahigh's original no start data, shown in Dellmassive's post #12 - except for one line, presumably when the key was turned to start position?

My assumption is IDE00412 is indeed only a recording of the key in start position. In the snippet below the key was very briefly flipped into start position - just to catch the timing of events following it.

There are quite a number of parameters available - unfortunately only 12 can...

• mmi

• 
• 

Post in thread 'Which Jump Starter?'

21 Oct 2018

And off course jump starting.... now needed it on our vans yet.... but used numerous times to help out others.

So that's in the real world. But in theory?

T6 diesel engine start-up

Measurements were done using a VCDS cable, achieved time resolution 130 ms.​

Timeline of events :

• Timestamp 3.5 sec: Initiate starting by turning key to position start
  
  Preglow, power up of ECU+other modules, lights, etc​
• Timestamp 5.2 – 6.0 sec Engine cranking, drain from battery peaks at 400 A for 0.3 sec
  
  Afterglow​
  ...

• mmi

• 

MAN

 

[Phil_j89]

Genuine replacement parts?

 

[Mo_baig20]

Genuine replacement parts?

Yes new glow plugs and new module