'02 Glow plug harness replacement (56k warning!)

tdi_allan

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Feb 14, 2003
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Chicago, IL
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2003 Jetta Wagon, 2003 Jetta Sedan (Lemons racer), 2010 Touareg
\'02 Glow plug harness replacement (56k warning!)

Well, the CEL finally drove me over the edge. I've had the new gp harness for a while, but cringed at the thought of crimping wires on my 2 year old car. Besides, why was the wiring so long on the new harness? Bentley was suspiciously quiet on the subject. Follow along as I chart new territory (for me, anyway...
) I even have a few pictures to go along with the story!


It always pays to start with the right tools. 10 mm, 13mm sockets, screwdriver, shop towels, a bottle of water and the new harness.


Here is the part number in case you need it.


After removing the engine cover, battery and airbox, this is what you see. That black plastic thingamajig comes off fairly easily after you pull up some of the hood trim at the top.


Jackpot! The white arrow points to the double-secret gp harness connection. I was quite surprised to find the gp harness wrapped with a bunch of other wiring! At this point, I was beginning to see why dealers charged a bunch of green to replace this.



So, I carefully unwrapped the cloth electrical tape from the wiring that the gp harness was wrapped in. Yes, this took a while. No, I did not cut any important wires.





These are pics of the separated gp harness from the rest of the wiring it was trapped with. Note the TT shifter I installed while waiting for Dad to return with something suitable to re-wrap the wires in.



As long as all of this was apart, it was Cage Mod time! One of these days I'll get the rest of the car's connectors (this one and MAF so far.)


This is what I used to re-wrap the wiring. Not nearly as sticky as the cloth junk. I wrapped the gp harness separately, to make future replacement that much easier.

For everything else, installation is the reverse of removal.


Hope this helps someone out there, its a lot of work but worth it to do the job right. Those of you with pre-02 cars can crimp and be satisfied because there is no harness connector on those applications.
 

TDICa

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Joined
Jun 26, 2003
Location
Sacramento, Ca
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02 Jetta GLS Black
\'02 Glow plug harness replacement (56k warning!)

You know this was covered under dealer warranty. Yes they do a sloppy cut and crimp job, but I was too lazy to do it myself. Good write-up - I probably redo mine when I have some free time on my hands.
 

Wingnut

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Oct 10, 2002
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Toronto & Whitby
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Silver 2003 Jetta Wagon
\'02 Glow plug harness replacement (56k warning!)

Great job. I will post a link to this writeup in my "Glow plug how to" thread for those who plan to do it too.
 

tdi_allan

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TDI
2003 Jetta Wagon, 2003 Jetta Sedan (Lemons racer), 2010 Touareg
\'02 Glow plug harness replacement (56k warning!)

Thanks Wingnut, I had no idea my post would be worthy of inclusion in "Glow Plug 101"
Now that I know where everything is and have the gp harness separated, it is likely I will never have to do the job again.
 

cage

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Mar 25, 1999
Location
lakewood, ohio
\'02 Glow plug harness replacement (56k warning!)

I wondered. When I did mine I asked and people said that you had to cut it. That the harness is a generic one used for all kinds of VW diesels. Oh well, next time I'll do it right.
 

dzlchef

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Jun 12, 2004
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Redondo Beach, CA
TDI
Previously 02 Jetta TDI
\'02 Glow plug harness replacement (56k warning!)

Thanks for the write-up. I am planning on doing this soon for the same reoccuring problem on my 2002 and was dreading undoing all the wire wrap and then I had an idea. Why not just cut out the old harness and connector and just wrap the new wiring harness along the same path of wires. There is no need to unwrap everything if you're not going to use the wires anyway, right? Who cares if there are some loose unused wires wrapped in the bunch with the others. I think that I just saved myself a lot of extra time.
 

mycruiseagent

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May 2, 2001
Location
Zephyr, TX
TDI
Jetta GL, 2002, Galactic Blue - R.I.P.
\'02 Glow plug harness replacement (56k warning!)

... Why not just cut out the old harness and connector and just wrap the new wiring harness along the same path of wires ...
What dzlchef said. The value here is the location of the mystery connector - that said ... great find and write-up!

MCA
 

tdi_allan

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Chicago, IL
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2003 Jetta Wagon, 2003 Jetta Sedan (Lemons racer), 2010 Touareg
\'02 Glow plug harness replacement (56k warning!)

... Why not just cut out the old harness and connector and just wrap the new wiring harness along the same path of wires ...
What dzlchef said. The value here is the location of the mystery connector - that said ... great find and write-up!

MCA
Excellent point. Where were you guys in September?
Oh well, it was fun unwrapping and rewrapping the wiring harness...
 

Nutsnbolts

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Joined
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Weare, NH
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2000 Jetta, Silver Arrow
\'02 Glow plug harness replacement (56k warning!)

As a footnote, I think it might behoove those of us who have the pre-'02 models to get that connector and install it in the secret location should we ever have to change the harness. As stated before, it make the change that much easier, and you will thank yourself if you ever have to do it again. Fortunately, I haven't been down this road yet (looking for something wood to knock on), but thanks for an excellent and informative post!

-Rich
 

MOGolf

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\'02 Glow plug harness replacement (56k warning!)

As a footnote, I think it might behoove those of us who have the pre-'02 models to get that connector and install it in the secret location should we ever have to change the harness. -Rich
the 'secret connector' had been previously posted, and is the same location for pre-02 models. The pre-02 models have just 2 heavy gauge wires at the connector. These go all the way to the gp harness. Each wire then feeds 2 gps inside the harness pre-02.
 

CGR

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Aug 27, 2003
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Pittsburgh, PA
TDI
2002 Golf TDI manual. Silver/Black
Re: \'02 Glow plug harness replacement (56k warning!)

Can someone give me the part number for the four wire harness. I can't make it out off of the picture. I have tried two dealers and the both say that the harness for my 02 is the 2 wire kind. The one dealer insists I am wrong and that I have bad info on my 02. The other dealers mechanics agree with me and that dealer has a 4 wire harness in stock for an 03 with a part number of 038 971 782 C

The parts guy and myself are thinking the harness they have for the 03 will work. Has anyone else run into this problem?
 

weedeater

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Reston, VA
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Jetta, 2001, Baltic Green
Re: \'02 Glow plug harness replacement (56k warning!)

IIRC, the change over to the 4-wire occurred in the middle of the 02 model year.
 

kirmet

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Nov 23, 2003
Location
WV
TDI
2002 Jetta Galactic Blue
I have my 02 tdi tore apart today to check the GP's and harness and would like to know a couple things.

Whats a TT shifter?

What is and why is it called "double-secret gp harness connection."?

Last but not least what is the cage Mod?
 

tdi_allan

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2003 Jetta Wagon, 2003 Jetta Sedan (Lemons racer), 2010 Touareg
'02 Glow plug harness replacement

kirmet said:
I have my 02 tdi tore apart today to check the GP's and harness and would like to know a couple things.
Whats a TT shifter?
What is and why is it called "double-secret gp harness connection."?
Last but not least what is the cage Mod?
The "TT Shifter" is a different version of the golf club-shaped weight on top of the shift mechanism. I installed the same part from an Audi TT for shorter front-to-back shift throws.
It really should not be called a "double-secret" harness connection, as MoGolf has pointed out earlier in this thread. (it was a secret to me, but my ability to read my Bentley manual and wiring diagrams is not up to snuff... :))
A search on "Cage Mod" here at TDIClub will explain the use of dielectric grease in electrical connectors, most notably the MAF sensor connection.
 

Sports Wagon

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May 21, 2006
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Land of Strong Beer. HAFB, UT
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The wife drives an 02 Jetta
I just changed the GP harness on the wifes 02 TDI. At first I was pissed about having to spend hours routing the harness and I wasn't to up on cutting and splicing the new one in. So I thoung about for a minute and came up with a way to install it in less than 15min. Is it getto? Mabey. Does it get the job done? Yes! Does it look clean? Yes.

All did was wrap the new harness with some wire wrap then plugged it in.

Routed it under the air box and over to the GP's. Done and done!

Here are the pics.










 
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rdean

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Jan 17, 2004
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Aspen Hill, Maryland
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Jetta, 2001, Bright Green, Jetta, 2002, Blue Lagoon (RIP)
Great write up- but I didn't find it in Wingnuts how to's. I didn't read the entire post before going out to do mine and wound up using the "getto" method. Too much hassle to unwrap allthose wires, looks good and will be easier IF teres a next time. Also, the location of the connecter was "news" to me. Thanks again
 

kc5833

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Apr 29, 2006
Location
Albany,NY
TDI
2002
Would it be possible to get to the gp connector unplug it clip the head off the connector leave the original wires (dead) in its original spot and just tape the new gp harness wires in the original place as factory. The dead wires can remain under the cloth tape and the new wires could be electric taped to the existing cloth tape and be routed in the same place. without unwrapping anything. hope I explained this well.
 

Sappington

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Manassas, VA
TDI
2017 Chevy Volt now -- sold '03 Jetta Wagon :-(
kc5833 said:
Would it be possible to get to the gp connector unplug it clip the head off the connector leave the original wires (dead) in its original spot and just tape the new gp harness wires in the original place as factory. The dead wires can remain under the cloth tape and the new wires could be electric taped to the existing cloth tape and be routed in the same place. without unwrapping anything. hope I explained this well.
That sounds like what dzlchef was saying on the previous page.

I didn't see tdi_allan say anything about cutting or crimping wires. Does that need to be done? Under what circumstances?

I've got an '03 Jetta Wagon and '03 Beetle, BOTH of which need harnesses. I think one has a 4-wire and the other has a 2-wire. Will the installation procedures be different between them?
 

tdi_allan

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2003 Jetta Wagon, 2003 Jetta Sedan (Lemons racer), 2010 Touareg
Sappington said:
That sounds like what dzlchef was saying on the previous page.

I didn't see tdi_allan say anything about cutting or crimping wires. Does that need to be done? Under what circumstances?

I've got an '03 Jetta Wagon and '03 Beetle, BOTH of which need harnesses. I think one has a 4-wire and the other has a 2-wire. Will the installation procedures be different between them?
I didn't cut or crimp any wires when I replaced my harness back in....when was that now? Looking back, the "ghetto" method seems like a good alternative to my painstaking wire unwrap/rewrap. Cut out the old harness where it pops out of the wiring loom and replace with the new harness. Pretty easy, actually. Use the new harness in its entirety under the plastic wiring loom cover and forget about the old wiring.

Your 2003 TDIs should both have 4 wire harnesses - if they don't, someone else has given them a completely different ghetto treatment. Installation is the same for both. Have fun!
 

captain

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Jan 28, 2007
Location
North Carolina
TDI
2001 Jetta TDI (manual) - SOLD;2002 Jetta TDI(auto) - SOLD
Thanks to everyone contributing to this site, yet again.

I just replaced my harness. Not bad at all, using the ghetto method. Two things were revealed to me while doing it.

First, you can gain additional access from the top by removing the plastic cover from where it attaches at the top. This way, you get much more access to the harness. Not sure if it can be done just going through the side (as above). I'm thinking most people are doing it this way. Just thought I'd mention it.

Second, this has been done on my car previously. One owner before me who had the dealer do everything. Yes, snipped wires at the end of the harness at both ends. So the dealership did this at one time. I hadn't noticed that the harness in place was routed pseudo fashion like the old. It does go beneath the air intake and the battery. I can see the dealership doing this. It was also wrapped in electrical tape (much like further up in this doc).

Anyway, thanks again.
 

Texas_sky

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Dec 23, 2007
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ATX/Mile Hi
TDI
2001 GOLF TDI 2dr 5spd
Does anybody have a step by step 1. 2. 3. 4. procedure/directions for the ghetto way? So you just route the wires where the previous GP harness wires were? Do you remove the old GP wire harness or does it stay in the car. I will have to take out battery and airbox right? What do you use to wrap the harness wires with?

Decided I'm gonna splice into the 4 wire harness, and hide the cut right around where the harness goes into the heat wrapping. Does anybody know where to get the butt connectors or heat shrink?? And what size I will need to complete the job?

thanks!
 
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Texas_sky

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2001 GOLF TDI 2dr 5spd
Question for those who did it the ghetto way. What happens with the original wires, do the wires stay dead in the engine bay, so you just cut the head off where it plugs into so the new one can plug in. Where do you cut the wires at to release the old rubber harness section.
 

Sappington

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2017 Chevy Volt now -- sold '03 Jetta Wagon :-(
I just did the harness change on my '03 Beetle. I just left the wires dead in engine. In fact, the harness is VERY difficult to get out from underneath fuel injectors, so I cut the wires right at the base of the harness and pulled it out in the other direction.

In this image I'm holding the old Glow Plug Harness connector. I just unplugged it and left it tucked underneath that black plastic casing.



Here's the new harness wiring in place, and I've started to tape it up:



Here I've put the black plastic casing back on and have taped the rest of the harness. There's a ton of wire with it, so I bunched it together and taped it which is why I've got that big blob there. The air box goes back on top of that which isn't a problem.



A good suggestion was made to also put some plastic wire conduit around it, too, for extra protection:
 

ozpassatwagon05

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Dec 24, 2007
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Stafford, VA
TDI
05 Passat Wagon TDI
i just got the GP codes for my #1 and 4 GP's. i wanted to know if anyone out there knows if the .5-1.5 ohm value is the same for an 05 passat wagon tdi. and also if the harness connector is the same?
 

MOGolf

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2001 Golf GLS TDI Reflex silver, rough road suspension and steel skid plate, 2004 Passat Variant, Candy White, rough road suspension and geared balanced shaft module, and much, much more. 2016 LR RR HSE TD6, 2019 Jaguar I-PACE
No. Resistance is 1 ohm or less.
No. Wiring is completely different.
And they are numbered on the engine as 4 is closest to the front, and 1 is at the back, of the engine compartment.
 

ozpassatwagon05

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05 Passat Wagon TDI
thanks mogolf.
i should be pulling the covers off tomorrow weather permitting and ringing them out.

so i will be checking for 1ohm, i read on the glow plug 101 about a possible split that could trigger a code. would you know what that split is?

last but not least is the harness relatively straight forward to replace.
 

MOGolf

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2001 Golf GLS TDI Reflex silver, rough road suspension and steel skid plate, 2004 Passat Variant, Candy White, rough road suspension and geared balanced shaft module, and much, much more. 2016 LR RR HSE TD6, 2019 Jaguar I-PACE
You should have started a different thread since the 05 Passat is not an '02.

The Passat does not have a harness like the older engines. Individual wires go to each. If a connector goes bad, you'll have to get a new connector to splice onto the engine wiring harness. Check the glow plugs first. Don't assume you need to repair the connectors.
 

ozpassatwagon05

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Stafford, VA
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05 Passat Wagon TDI
oops!! i apologize for this oversight... i saw different vehicles mentioned here but didnt zero in on the 02 factor. thanks for the tip, and if any other questions come up i guess i should post them under the passat section...

once again thanks for the savvy advice mogolf!


NOTE: started thread under passat section
 
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