[79westy]

I'd like to pressure test the cylinder in question with a pressure guage. I only have experience pressure testing gasoline cylinders. Do I need to remove all 6 glow plugs, or can I just remove the glow plug on the cylinder I'm testing? Do I need to shut down the fuel system so the vehicle doesn't run? If so, what is the simplest way to accomplish that? Any other suggestions?

 

[79westy]

Update:
After replacing the #2 glow plug (the one with the sensor) with a brand new genuine VW part, the problem persisted. So I replaced with another new glow plug 2, this time OEM Beru. This did not resolve the issue. So I asked a local mechanic for help.

We used a testing procedure that he acquired from All Data DIY.
Test one was to check resistance from terminal 92 to terminal 71 in T105 at the ECM. Listed Spec is 4.0 Mohms (+/- .7 Mohms). The currently installed New Beru OEM glow plug measured about 5.2 Mohms at first, with later tests reading between 6.5 Mohms and 7.7 Mohms (I cannot explain the change, nor could we get tests to repeat 5.2 Mohms). We then ran the same test with the other 2 glow plugs we had on hand. The old used plug (unknown age/mileage) measured about 12 Mohms, while the brand new genuine VW glow plug measured around 12 Mohms as well.

Next, we measured resistance from the Glow Plug 2 electrical harness connector to the following terminal locations in the T105 harness to ensure they were less than the specified value of 1.5 ohms, which they were. Locations- 50, 92, 71

So… Do these test results indicate that my Glow Plug 2 failed, and I replaced it with a defective brand new Genuine VW Glow Plug 2, which I then replaced with a defective brand new Beru OEM Glow Plug 2?

What am I missing?

 

[SaVAGeSoot]

What am I missing?

• electrical understanding
• diagnostic skills
• an actual mechanic

If whatever checks you've done thus far have actually passed, I'd be surprised if all GPs were indeed fubarred...
The higher than expected resistance would indicate to me a flaky PSG connection, so without knowing anything else here, I'd replace the harness..... but that's only if I was taking the cannon approach like you are. (because, I'd actually locate the issue first)

 

[volkswagens-for-life]

• electrical understanding
• diagnostic skills
• an actual mechanic

If whatever checks you've done thus far have actually passed, I'd be surprised if all GPs were indeed fubarred...
The higher than expected resistance would indicate to me a flaky PSG connection, so without knowing anything else here, I'd replace the harness..... but that's only if I was taking the cannon approach like you are. (because, I'd actually locate the issue first)

Jesus, leave the guy alone... He already says he doesn't want to use a computer system that could tell him within minutes with the issue is and he would rather do this the old-fashioned way like it's the '70s all over again

 

[79westy]

Jesus, leave the guy alone... He already says he doesn't want to use a computer system that could tell him within minutes with the issue is and he would rather do this the old-fashioned way like it's the '70s all over again

When did he say that? He may not know how to use a computer in such a way. I thought that was the point of forums like this... To help him learn. You guys love this stuff, 'ey?

 

[volkswagens-for-life]

When did he say that? He may not know how to use a computer in such a way. I thought that was the point of forums like this... To help him learn. You guys love this stuff, 'ey?

Am I mistaken in believing you are the guy refusing to buy VAGCOM and preferring to do things the old fashioned way of crawling around on your hands and knees? if I have you confused with someone else I apologize.

 

[SaVAGeSoot]

You on the bottle again Matt?

 

[volkswagens-for-life]

You on the bottle again Matt?

Seems like it. I must have been thinking of another guy that refuses to use VAGCOM. My bad OP

 

[SaVAGeSoot]

🍻

 

[Brendanm]

Using an ohmmeter to check wiring integrity is basically pointless. There is zero load, and you can have a bad connection/corrosion etc and have an ok resistance reading. A much better way is to use a test light (proper one not an led one). An ohmmeter would only be helpful in this instance when checking for a short across two wires that shouldn't be joined, but may be by corrosion, harness rubbing through etc.

 

[79westy]

After someone suggested that the mechanic's meter sounded suspect, I asked him to compare it to a different ohm meter tonight and it was out of whack. So consider every test performed in post 42 to be inaccurate. I repeated the procedure tonight and posted a video summary of that test below.

 

[79westy]

Using an ohmmeter to check wiring integrity is basically pointless. There is zero load, and you can have a bad connection/corrosion etc and have an ok resistance reading. A much better way is to use a test light (proper one not an led one). An ohmmeter would only be helpful in this instance when checking for a short across two wires that shouldn't be joined, but may be by corrosion, harness rubbing through etc.

I get what your saying here. To test the wires in question with the test light method, would you just drive the tip of the test light through the insulation of each wire while fully connected as normal (i.e. ecm on one end, glow plug on the other)?

 

[Brendanm]

I get what your saying here. To test the wires in question with the test light method, would you just drive the tip of the test light through the insulation of each wire while fully connected as normal (i.e. ecm on one end, glow plug on the other)?

No, do not do anything with anything plugged in, and do not pierce any insulation. You have both ends of the harness disconnected, ground one side of the harness, test the other end with the test light, with clip of the test light connected to positive. This does not work with an LED test light, has to be incandescent, as they actually draw a semi decent load.

 

[79westy]

Update -I am attempting to put a bow on the wonderful thread. I purchased part VAG-04L971785C from FCP Euro (Item 04L971785C). I ran the pig tails for the sensor wires the whole way to the back of the T105 harness and soldered them in to replace the original wiring. I spliced the actual glow plug wire into the original one as well. This repaired the problem. Thanks to those of you who tried to help.

 

[SaVAGeSoot]

At least you finally got there!