Possible Glow Plug Harness Cure

There have been LOTS of posts about glow plug problems. When the code is thrown, it could be caused by several different factors. A bad plug or plugs (usualy), a corroded harness (often), or a bad relay (not very often).

Luckily, the most expensive option is the last one, so glad its not very common. A simple test can confirm or rule out a bad glow plug. So if they pass the test, then the code was likely thrown by a slightly corroded harness.

I found this product that may be able to help those who have chronic glow plug codes. Its cheaper, easier, and less invasive than changing the harness and may eliminate the triggering of MIL's.

For a complete list of distributors, click on the distributor icon at the top of this page

I also found this product from the same manufacturer. Not sure which one would be better?

EDIT: While placing an order for these products, I also found this one. It looks like it might be even better than either of the other two? It claims:

Improves conductivity
Deoxidizes, cleans, preserves, and lubricates
Reduces intermittents
Reduces wear, abrasion, arcing and RFI
Stabilizes connections between similar and dissimilar metals



Exaclty whay we are looking for to cure the harness problems.

I would opt for the product behind curtain number two. For glow plugs, the heat rating is in it's favor. I've been telling people to use Ox-Gard but... I have it on good authority it doesn't like heat and will dry out. This looks to be a better alternative considering it's 200ºc rating.

I wonder - any chemicals in either which might react badly to the wide range of temperatures, humidity and other elements found inside an engine compartment? Just a thought... my TDI doesn't have enough mileage for the glowplugs to be an issue, so I will be the first to admit i'm not exactly an expert here. Haven't had to take one out yet, or test it, etc.

For whatever the reason milage and or time does not seem to make a differance in the lasting of glow plugs. [ QUOTE ]
my TDI doesn't have enough mileage for the glowplugs to be an issue, so I will be the first to admit i'm not exactly an expert here. Haven't had to take one out yet, or test it, etc.


[/ QUOTE ] But as long as it starts good i would not worry about it. Now on the early rabbits 1 bad glow plug and you had a problem. I have started this 01 in 0% weather WITHOUT using the glow plugs ( took fuse out) and while it started slower it still started.

That's what i'm saying - I haven't had the joy of having a problematic glow plug yet. Mostly, since i don't know much about the way they connect to the car, how the harness is protected, etc, I have no idea if my question about chemicals and engine compartment conditions is a valid one or not. If it is, i'd love to hear the answer. If it isn't, then it would seem that either product would fit the bill.

Either way, thanks to wingnut for doing the research on this. Very useful info.

cheers.

A bit of preventative maintenance could save lots of future agrivation. There have been a rash of phantom glow plug codes thrown and since there is no way to test the harness, the only way to eliminate it as the cause is to either replace it or try to treat it. Checking the plugs themselves is easy. So is checking the relay. So if those check out ok, then the harness seems like a logical place. I took my old harness apart to see why it would be bad.

Here are the pics I took:


As you can see, the two center liners are severely oxidised and scorched. The scorching is probably as a result of arcing due to the poor contact caused by the oxidation. So treating it is a viable solution if you catch it early. But treating it early & regularly is also good preventative maintenance.

This harness caused my MIL to come on 4 times within a months time. Each time returning within from a few to 400km after having it cleared. I have not had a CEL in a year now & 40k km. So obviusly, the harness was my problem.

I read this whole discussion but I still posted the same question. Myself and the mechanic shot the whole harness and every connection while moving the entire harness and no shorts or jumps in voltage occurred. So do you think it could still be a harness problem?? /images/graemlins/confused.gif HUD

[ QUOTE ]
HUDF162049 said:
I read this whole discussion but I still posted the same question. Myself and the mechanic shot the whole harness and every connection while moving the entire harness and no shorts or jumps in voltage occurred. So do you think it could still be a harness problem?? /images/graemlins/confused.gif HUD

[/ QUOTE ]

the GP have a very low resistance. A slight resistance in the harness will change the total resistance dramatically. (you may not be able to see it on a meter while wiggling the harness, try a scope)
this will set off the CEL.

I have been spraying WD40 in mine and thus far have the original harness.

Thanks I'll give it a shot. I'll let you know how it turns out.. /images/graemlins/smile.gif

Found another product. Check original post for details.

Ok. I got my shipment in today. I got one each of the Deoxit D5 & the Super contact cleaner:



Here as what is written on each can:

Deoxit D5:
- Improves conductivity
- Deoxidises, cleans, lubricates & preserves
- Reduces connection failures
- Reduces wear & abrasion
- Reduces arcing & RFI
- Temerature range -34* C to 200*C
- Effective on similar & dissimmilar metals
- Use on stationary & moving connections

Super Cpontact Cleaner:
- Cleans, lubricates & protects
- Eliminates oxidation
- Improves conductivity
- Safe on most plastics
- Molecularly bonds to all metals.

So I would have to say that while both seem to have the characteristics we are looking for (contact cleaning, contact enhancing & deoxidising) it looks like the DeoxitD5 looks like the better product due to its temp rating. But it was also more expensive. I will have a chance to test these products on the weekend as I have someone with a GP fault coming over to clear his MIL.

But even if you don't have a glow plug fault, I would still recommend picking up one of these products to treat your harness and use it as preventative maintenance. There are way too many glow plug faults being reported. And many are not glow plug related, so instead of spending $25 to replace your harness, just spend $10 and treat it before it becomes a problem. I will bring these cans to all future GTG's if anyone local wants a squirt.

Here's a little more info on deoxit:
http://www.intendedacceleration.com/html/tip_14.html
and also some info on Stabilant 22 that is said to be good to use after using deoxit:
http://www.stabilant.com/
Apparantly stabilant 22 can be bought at vw, napa, uap.. I'm going to check it out today and check out the price.

Rich

I use DC 4 compound From Dow Corning. This stuff is good, /images/graemlins/laugh.gif I use it at my job often. The price is a little high but worth it. This is just one link I found to show what it is. One tube will last a long time.


Chief Aircraft Inc.

Unfortunately DC-4 Compound is a di-electric compound. I think I want the most current I can get and the best conductance I can get at the connection to the glow plugs.

Another A&P...

stabiliant 22a is cheapest when purchased from Motorola, but it's still in the $30-40/bottle range. I can dig up the info if there is serious interest. The Caig products are very good for their price.

Stabiliant 22 is good stuff. Rolls-Royce calls for it to be applied to the ITT harness connections on AE3007 engines. Keeps the corrosion out and maintains good conductivity for the electrical signals. Not to mention the connectors are located in a fairly "warm" enviroment.

Ox Gard worked for me. No more P0380 CELs some 20K later. Got it at HomeDepot

Well I will have to give this a try. My NB and my sons Jetta has this problem. Will keep you posted.

Greg

I have worked with ignition systems and have experienced problems concerning spark plugs in gasoline engines. What I use is an electric conductant compound that reduces the chances of oxidation and corrosion, it also makes the harness easier to get off the next time. This preventative could probably be purchased at a vast majority of parts stores and can be applied to the head of the glow plug that connects to the harness. <font color="black"> </font>

I have found a test I like very much to test the glow plug harness.

Take an old glow plug, Grind off the locking ring that holds the harness on to the glow plug ( look at the two parts together you will see). Now insert the glow plug into the harness you will now feel the drag caused by electral conection and not the locking ring. Test them all. I have found that often more than one is loose. If they are you can replace the harness or just clamp on the outside to tighten them up. Then recheck with the tool you just made.

Audiophiles know and cherish CAIG products.

They have saved multiple televisions; computers; anything
that requires a clean electrical connection.

Might also check out the outdoor version of VCI - vapor
corrosion inhibitor.

Every piece of audio/video gear that I buy gets a few
sprays of VCI on the internals - helps prevent PCB trace
corrosion; relays from "gumming up"; high resistance
connections - the usual stuff we all experience at one time
or another.

And if you smoke - you gotta use some good cleaner on
audio connections - amazing how much crap builds up on
them - ask my sister who smokes.

good post!

Help!

(I swear it's no fun growing up as a girl who knows nothing about cars. You have saved my skin once before, so I'm counting on your a) expertise and b) SIMPLE explanation to help me.)

I've read this entire thread, but understand very little of it. My 2000 Jetta TDI's warning light went on. I brought it to the VW dealer and they said it would cost about $550 to replace the glow plug harness and relay. In that it was summer and I was leaving for vacation, I made some excuse and beat it out of there. My problem is this: I'd like to have someone check all of these handy-dandy possible cures you all have mentioned, but my old mechanic (that I momentarily gave up when my new car was under VW warranty) said that he's not really familiar with this harness. What can I tell him to look for (in case it's realy not the entire harness and all that needs replacing)? Can I equip myself with any of these products y'all have mentioned? Where would I find the GP harness (and won't I get electrocuted?!)? What does "When the code is thrown" mean?

I have about 77,000 miles on the car.

I throw myself on your mercy. . .
Tasia

Help!

(I swear it's no fun growing up as a girl who knows nothing about cars. You have saved my skin once before, so I'm counting on your a) expertise and b) SIMPLE explanation to help me.)

I've read this entire thread, but understand very little of it. My 2000 Jetta TDI's warning light went on. I brought it to the VW dealer and they said it would cost about $550 to replace the glow plug harness and relay. In that it was summer and I was leaving for vacation, I made some excuse and beat it out of there. My problem is this: I'd like to have someone check all of these handy-dandy possible cures you all have mentioned, but my old mechanic (that I momentarily gave up when my new car was under VW warranty) said that he's not really familiar with this harness. What can I tell him to look for (in case it's realy not the entire harness and all that needs replacing)? Can I equip myself with any of these products y'all have mentioned? Where would I find the GP harness (and won't I get electrocuted?!)? What does "When the code is thrown" mean?

I have about 77,000 miles on the car.

I throw myself on your mercy. . .
Tasia

Click to expand...

Look at the bottom of the post by the guy named 'Wingnut.' There, you'll see a link call 'How-to.' There's a link on that page which goes over (quite extensively) the procedure and cures for glowplug faults. You may want to print out the post and take it to your mechanic. The post will also help you locate your GP harness and all related parts. The phrase 'throwing a code' is simply geek talk for your vehicles computer noticing a 'problem' and notifying you by triggering the engine warning lamp. When your mechanic plugs in his computer to your car, he reads the code 'thrown' by the car so he can figure out what's up.

Ryan

Thanks for this info Wingnut! I have been driving myself crazy with poor starting and not being able to figure out what the problem is. The symptoms point to a GP issue (no CEL) since it is only when the temp drops. I have ordered the Deoxit and hopefully my woes are cured with one squirt!

Stan, have you ever had your base timing checked?

I was just about to ask the same thing. The glow plug harness has little effect on starting. The big problem with them is that they develop a small amount of corrosion or oxidation in the linings that causes a variation in resistance. This is detected by the ECM so it thinks there is a bad plug. In reality, everything could be just fine. So unless you have a CEL, this will not fix a hard cold start. But treating the harness will help to make sure you never get the CEL, so consider it preventative maintenance.

To fix the cold starting issues, have your timing checked as per Weedeaters suggestion.

Thanks for the suggestion. I've saved as a PDF file the entire file that Wingnut (and everyone) wrote and will print it out and bring it to my mechanic.

Thanks for coming to my rescue once again! You guys are great.

Tasia

Sar: why not do the work yourself? it is not that hard all you have to do is buy a meter at radio shack or sears for 10$.

Audiophiles know and cherish CAIG products.

They have saved multiple televisions; computers; anything
that requires a clean electrical connection.

Might also check out the outdoor version of VCI - vapor
corrosion inhibitor.

Every piece of audio/video gear that I buy gets a few
sprays of VCI on the internals - helps prevent PCB trace
corrosion; relays from "gumming up"; high resistance
connections - the usual stuff we all experience at one time
or another.

And if you smoke - you gotta use some good cleaner on
audio connections - amazing how much crap builds up on
them - ask my sister who smokes.

good post!

Click to expand...

CAIG SK-IN30 TECHNICIANS SURVIVAL KIT

CAIG website

I had the same problem in my 2001 Jetta. DetoxIT was the cure and my check wallet light has not come back to haunt me.

I was able to purchase it at Fry's Electronics for $8.99 They also sell the super contect cleaner and a few others.

Has anyone tried the DetoxIT Gold?

GP.