I'm sure those plugs are for a V6 and NOT for a TDI.

 

V6 TDI

 

Glow plugs can be tested using a digital multimeter. Below is a video showing how. Keep in mind the glow plugs in the video may not have the same top connector as yours so you have to make sure you're connecting the test lead to the correct spot where the connector goes.
As far as how easy they are to access I can not say. Maybe using the "Search Community" feature at the top center of the page will bring up threads on your year/engine to show how.

Testing glow plugs

 

There is no reason to test the glow plugs manually- if your ECU says they're bad, they're bad.

Your vehicle takes two different kind of glow plugs in different locations- 4 are without a cylinder pressure sensor, and 2 are with one and will be substantially more expensive. Definitely make sure you get either Bosch or VW branded ones and not a cheaper brand. Testing with a multimeter probably won't tell you if the pressure sensor ones are bad.

Personally, I prefer to just replace failed plugs one at a time rather than doing the whole set at once. Besides being cheaper and easier, I think it also staggers the chance of failures so you're less likely to get enough failures at the same time to actually affect starting.

 

There is no reason to test the glow plugs manually- if your ECU says they're bad, they're bad.

It just says there is a problem with the circuit. Could be the glow plug, or could be a wiring problem. Don't want to replace a plug, put it all back together, and find the problem is still there because there is a broken wire going to the glow plug.

What is the pressure sensor plug do? I don't see an extra connector on it, so how does it measure pressure and for what reason? Can it be replaced with a regular glow plug or will that cause more problems?

 

It's your choice, but glow plugs fail often, and wires to glow plugs do not- they're massive wires with high quality corrosion proof connectors. If you really want to do a test, you can swap two glow plugs of the same type and confirm that the code moves to the new location.

The pressure sensor provides internal cylinder pressure to the ECU, which can for example allow it to tell how quickly different quality fuels, e.g. with different cetane ratings are burning, and adjust the injection timing and fuel quantity accordingly.

The two plugs with a sensor will have a different, two wire connector.

 

An update on the issue. Replaced the two glow plugs throwing the codes. There were certainly bad. One reading 800 ohms and the other 25. Now those codes are gone but in their place I have these glow plug controller codes,

001612 - Glow Plug Control Module
P064C - 000 - - Intermittent
Freeze Frame:
Fault Status: 00100000
Fault Priority: 2
Fault Frequency: 1
Reset counter: 255
Mileage: 296126 km
Time Indication: 0
Date: 2024.11.18
Time: 14:33:11

Freeze Frame:
RPM: 0 /min
Speed: 0.0 km/h
Voltage: 10.94 V
Temperature: 17.1°C
Temperature: 18.9°C
Absolute Pres.: 989.4 mbar
Torque: 0.0 Nm

001612 - Glow Plug Control Module
P064C - 001 - - Intermittent
Freeze Frame:
Fault Status: 00100001
Fault Priority: 2
Fault Frequency: 1
Reset counter: 255
Mileage: 296126 km
Time Indication: 0
Date: 2024.11.18
Time: 14:33:11

Freeze Frame:
RPM: 0 /min
Speed: 0.0 km/h
Voltage: 10.94 V
Temperature: 17.1°C
Lambda: 14.1 %
Temperature: 18.9°C

Also, I tried a new starting method. Let it glow and crank for just 5 seconds, then turn it off and repeat. Low and behold, it started right up after the second crank at 45°F. Before it would crank for 20 seconds at 60° before starting. Will have to look further into those codes and what that controller does and where its located. Any thoughts?

 

An update on the issue. Replaced the two glow plugs throwing the codes. There were certainly bad. One reading 800 ohms and the other 25. Now those codes are gone but in their place I have these glow plug controller codes,

001612 - Glow Plug Control Module
P064C - 000 - - Intermittent
Freeze Frame:
Fault Status: 00100000
Fault Priority: 2
Fault Frequency: 1
Reset counter: 255
Mileage: 296126 km
Time Indication: 0
Date: 2024.11.18
Time: 14:33:11

Freeze Frame:
RPM: 0 /min
Speed: 0.0 km/h
Voltage: 10.94 V
Temperature: 17.1°C
Temperature: 18.9°C
Absolute Pres.: 989.4 mbar
Torque: 0.0 Nm

001612 - Glow Plug Control Module
P064C - 001 - - Intermittent
Freeze Frame:
Fault Status: 00100001
Fault Priority: 2
Fault Frequency: 1
Reset counter: 255
Mileage: 296126 km
Time Indication: 0
Date: 2024.11.18
Time: 14:33:11

Freeze Frame:
RPM: 0 /min
Speed: 0.0 km/h
Voltage: 10.94 V
Temperature: 17.1°C
Lambda: 14.1 %
Temperature: 18.9°C

Also, I tried a new starting method. Let it glow and crank for just 5 seconds, then turn it off and repeat. Low and behold, it started right up after the second crank at 45°F. Before it would crank for 20 seconds at 60° before starting. Will have to look further into those codes and what that controller does and where its located. Any thoughts?

Your common rail isn't even barely using glow plugs at 45°. The fact that you let it crank for a couple seconds, turn it off, let it crank until it started... Tells me that probably your battery is too shot to crank your engine fast enough to make the heat necessary in the cylinders for compression ignition. Like @SaVAGeSoot said check your battery data.

 

Look at the voltage in your FF
Your battery is junk

 

I recently put an Auto Zone Platinum H9 AGM battery in mine and it is amazing how fast it turns over and starts now.

 

Good choice.
Did you find yours was made by Johnson Controls also?

 

At 45° a common rail doesn't even need glow plugs.

What does common rail have to to with it?

My Touareg nor my power stroke nor my Cummins ever need a glow plugs of their temperature. All of those common round engines start within a couple seconds of cranking at those temperatures.

Modern diesels have fast start glow plugs. I would say that during those couple seconds of cranking, the plugs were heating up the cylinders. Otherwise, why in the Touareg, is there like a 5 second delay from when you press the start button and the glow plug light turns on, to when it starts cranking, if not to heat the plugs?

 

What does common rail have to to with it?


Modern diesels have fast start glow plugs. I would say that during those couple seconds of cranking, the plugs were heating up the cylinders. Otherwise, why in the Touareg, is there like a 5 second delay from when you press the start button and the glow plug light turns on, to when it starts cranking, if not to heat the plugs?

As much as I'd love to give a class, I don't have the time. Common rail injection operates at substantially higher rail pressure and injection pressure than previous forms of diesel injection. It's extremely clean and atomizes significantly better than previous forms.

Yes they sure do have fast start glow plugs. 38* yesterday morning. Didn't even wait for the grid heater on my Cummins. I turned the key, it started. Because common rail. None of my common rails get finicky until the 20s generally, and by finicky, I mean they'll actually cycle the GP or grids.

 

Look at the voltage in your FF
Your battery is junk

Your common rail isn't even barely using glow plugs at 45°. The fact that you let it crank for a couple seconds, turn it off, let it crank until it started... Tells me that probably your battery is too shot to crank your engine fast enough to make the heat necessary in the cylinders for compression ignition. Like @SaVAGeSoot said check your battery data.

So much for your theories on a bad battery.

 

That is the battery I just put in my Treg. I hope your experience isn't a bad sign for my future.

 

So much for your theories on a bad battery.

FF data doesn't lie....

Voltage: 10.94 V

 

You do realize glow plugs draw a lot of current....

 

Ok, thanks.... I'll make sure next time I try to fire up one of my diesels that the battery is under 11v prior to even cranking it..... I knew I was doing something wrong this whole time!

 

PS... if you're looking for another battery, I have a gently used one for you... give you a good deal on it... it's even stronger than yours was in your scan!

 

Your common rail isn't even barely using glow plugs at 45°.

At 45° a common rail doesn't even need glow plugs. My Touareg nor my power stroke nor my Cummins ever need a glow plugs of their temperature. All of those common round engines start within a couple seconds of cranking at those temperatures. It was 38° this morning and I didn't even hit the grid heater in my Cummins, literally turn the key on and it started immediately. Cranking too slowly will prevent enough heat from accumulating fast enough, bad battery.

Yes they sure do have fast start glow plugs. 38* yesterday morning. Didn't even wait for the grid heater on my Cummins. I turned the key, it started. Because common rail. None of my common rails get finicky until the 20s generally, and by finicky, I mean they'll actually cycle the GP or grids.

Just a note from VW on the temps that the glow plugs operate in. Not sure about your Cummins.

From the VW Self Study Program 840193 3.0-liter V6 TDI Clean Diesel Engine:

"Glowing
After switching on the ignition, the Glow Plugs Q10 – Q15 are switched on via the Automatic Glow Time Control Module J179 by the ECM at a temperature of less than 68°F (20°C). During the initial glowing phase, the Glow Plugs Q10 – Q15 are operated at a voltage of approximately 11 V for a maximum of two seconds.

They are then supplied with the voltage required for the relevant operating status by the Automatic Glow Time Control Module J179. To relieve the onboard power supply, glow plug initialization is phase-offset.

Post-Start Glowing
Post-start glowing is carried out each time after the engine has been started, in order to minimize combustion noise and reduce hydrocarbon emissions. Glow plug initialization is corrected by the ECM depending on load and engine speed.

Note:
Post-start glowing stops when engine coolant temperature reaches 95°F (35°C). Post-start glowing is interrupted after a maximum of three minutes."

You do realize glow plugs draw a lot of current....

They glow hot for the first 2 seconds, then PWM at around 4-5 volts, so not a terrible current draw in my mind.

 

Just a note from VW on the temps that the glow plugs operate in. Not sure about your Cummins.

From the VW Self Study Program 840193 3.0-liter V6 TDI Clean Diesel Engine:

"Glowing
After switching on the ignition, the Glow Plugs Q10 – Q15 are switched on via the Automatic Glow Time Control Module J179 by the ECM at a temperature of less than 68°F (20°C). During the initial glowing phase, the Glow Plugs Q10 – Q15 are operated at a voltage of approximately 11 V for a maximum of two seconds.

They are then supplied with the voltage required for the relevant operating status by the Automatic Glow Time Control Module J179. To relieve the onboard power supply, glow plug initialization is phase-offset.

Post-Start Glowing
Post-start glowing is carried out each time after the engine has been started, in order to minimize combustion noise and reduce hydrocarbon emissions. Glow plug initialization is corrected by the ECM depending on load and engine speed.

Note:
Post-start glowing stops when engine coolant temperature reaches 95°F (35°C). Post-start glowing is interrupted after a maximum of three minutes."


They glow hot for the first 2 seconds, then PWM at around 4-5 volts, so not a terrible current draw in my mind.

Yes they're PWM glow plugs. I didn't realize it was 68* that they start; that's likely only for smoothness and not required for operation. They're still not doing much in the 50s F and barely anything in the 40s

 

It's over 3 years old. The battery tester usually condemns even fairly good batteries, so if it says one is good, it's good.

 

Was 15 degrees F here this morning. The glow plugs ran for about 7 seconds before it started.

 

You didn't realize they start at 68° yet you assume it's only for smoothness and not required for operation? Where do you get that they're still not doing much in the 50s F and barely anything in the 40s? I mean, you seem knowledgeable on the subject but where do you get these facts?

IF the glow plugs run at 68* (which the ssp states they do), it's to ensure your $70,000 luxury car starts smoothly like you'd expect $70,000 to start like. They pulse width modulate for only two seconds to ensure a smooth startup; no smoke and no engine shake. The colder it gets, the longer the plugs cycle for ensuring proper start, no smoke and no engine shake. I've started my common rail powerstroke in the 20s and it complained a bit, but it started easily. The Cummins I've started at the same and colder while bypassing the grid heater and it didn't complain at all. V

I get these facts from running diesels over the past 16 years, owning probably 9 and driving hundreds. Common rail starts without much intervention when it's that warm.

Was 15 degrees F here this morning. The glow plugs ran for about 7 seconds before it started.

Seven seconds isn't bad at all. At 50* they're not effectively doing anything at all.

 

Update. Last two days it was 30° when starting. This time I just turned it on and let it glow, 2 times, then the third time with my foot on the brake it starts right up. Kinda leads to a faulty glow plug controller I would think. A scan with the Intermittent Glow Plug Control Module fault codes would tend to back that up I think.

 

Lol we're still doing this? It was 15 degrees this morning and I didn't give my grid heater 1 second to warm up and my common rail Cummins started immediately.

 

Come on man. Your Cummins diesel has about as much to do with this Touareg as your 1999.5 Jetta TDI does.

 

They're both common rail engines and quite similar. My 1999.5 Jetta had an electronically controlled Bosch rotary pump - not at all similar and wouldn't have started at 15* without cycling the glow plugs in a million years.

 

Started fine this morning at 11°F with my manual glow plug routine. Made a video.

 

Started fine this morning at 11°F

Amateur

 

Started fine this morning at 11°F with my manual glow plug routine. Made a video.

Man did you hear how that thing was struggling? That battery is so shot it barely turned that engine over

Amateur
View attachment 268713

You guys are both amateurs.. I started my 6.7 Cummins two days ago at 9° F and totally forgot to even hit the grid heater and it started right up 🫡

 

Man did you hear how that thing was struggling? That battery is so shot it barely turned that engine over

You should watch some diesel cold start videos. Mine was like new in comparison.

 

You should watch some diesel cold start videos. Mine was like new in comparison.

Oh yeah, I've seen plenty. I remember the dark ages of diesel. Heck I have a video on YouTube of my 1999.5 Jetta TDI doing a cold start only to realize it had gelled over and never ended up starting 😅

So you're raising my -23º with your -13º

View attachment 268749

🤡 🤡

 

Oh yeah, I've seen plenty. I remember the dark ages of diesel. Heck I have a video on YouTube of my 1999.5 Jetta TDI doing a cold start only to realize it had gelled over and never ended up starting 😅

Sounds like a video of a Cold FAIL 🤡