Replacing glowplug wires?

[Hubert]

I am gathering parts and info on glow plug and injector replacements. And had read of replacing glowplug wires at the same time. The drivers side connectors and wires are discolored (and look a little frail) but none broken. Can't see the passangers side much at all.

But looking at the wiring a little closer the glowplug wires appear routed inside a big bundle of wiring loom. When I went to a GM dealer to check on the wires he did not have a listing for glow plug wires (right off) but did have one for an engine harness. The exploded parts view showed several pieces but nothing looked like a good choice. The harness number below he gave me was from a telephone call he made to a gm parts hotline and I did not see a picture.

Looking at gmpartsdirectdotcom:

A diesel page thread said this was part number for a 98 truck glow plug wires
GM No. 15303052 - Engine wiring Harness
$83.35 gm list $43.34 gmdirectdotcom

From dealer
GM No. 15320904 - Engine wiring Harness
$42.13 gmdirectdotcom $24.97

Anyone know the correct wiring harness to order?

I am kind of leary to open up the wiring loom because I don't want it to look hacked on. How hard is it to replace the glowplug wires and reloom the bundle? Any advice other then zip ties and patience?

Or just leave old wires in loom and run new wires in smaller loom and zip tie it to OE loom?

[Robyn]

These wires dont usually give any trouble.
I have been into both my 94 Burbs and the wires were a little discolored but just fine electrically.
The issue is if any have gotten into the manifolds and been burnt.
The right side wires need to be accessed by removing the front wheel and the rubber water shield. You can then access the wiring. On the right it comes in under the manifold below the starter heat shield. The front and rear wires are just like the left side, the center two have a special extension that is a high temp wire and plugs onto the regular wire and goes down a little tube heat shield.
To get the center ones off you need either the special tool to pull the wires or you do as I do and remove the nuts holding the heat shield and slide the shield back so you can unplug the wires. The right rear is a Bitch but doable from below. With a cold engine *****
Unless you are having serious issues I would not spend the $$$$ on a new harness. The glow plug wiring is wound into the harness fairly deep and is not impossible to extract BUUUUUUUUUUUUUUT!!!
Both mine were perfectly serviceable at 200K + miles and still going strong.
Good luck
Robyn

[Hubert]

Thanks; advice appreciated. I will probably get more into it and reevaluate. Just hate to get into it and ready to put back together and wish I had new wires. I like my truck a lot and generally have a hard time deciding the cutoff of what to replace "while I am there". And sometimes its like plumbing if you have to fix one thing better figure on replacing anything that is touching it also.

I emailed gmpartsdirect customer service and this was reply:

15320904 engine wiring harness extension wire, used as glow plug jumper. Total of two used on your vehicle.

"Jumper" sounds like they don't hack into harness and just run additional wires. If so that sounds fairly easy if I need to replace them.

[diesel65]

If I am not mistaken the jumpers that GM Parts says that the 6.5 diesel has only two of, is used for cylinder #4 and #6. If you look by the starter you will see two grey connectors.

[Robyn]

yes this is correct.

These little sweethearts have a habit, if not properly restrained of getting too close to the down pipe and frying.
The main harness on the right side of the engine splits where it slides between the engine block and the heat shield by the starter. The number 8 wire is free and comes down behind the engine and plugs on the glow plug.
The wires for 2-4-6 run through under the shield and then 4&6 split off and the jumpers attach to them. The Jumpers are a special high temp wire and snake down the protection tubes to the glow plugs. Number 2 is a regular wire and follows the harness around and ends up at the glow plug. Any time you have the starter off its a good idea to check things out and make sure there are no bare spots on any of these wires.
If these wires are routed properly and fastened securely they should give many many years of good service. I replaced the jumpers on my Burb because one of them had fried on the down pipe. Too many folks just dont take the time to replace wire ties or clamps. I look at it this way, if the factory put it there in most cases its needed. The factory never spends money for things that can be done without..

[Hubert]

Grrrrrr!! I was a little wishful thinking and invisioned a little Jumper wire set similar to sparkplug wires.

Makes sense the turbo side would not ressemble the other side so they are probably the extensions for under the turbo.

I have been in the area (having starter off doing clutch) before but do not remember details of glowplug wires. Once the inner fender is out and I am into the job I will see things clearly.

I will email gmpartsdirect for a picture of this part number and ask specifically if they have a replacement set of wires. Or do you have to get a whole harness or ???

[Hubert]

OK after a few emails back and forth and confirmation of parts schematic:

15320904 is the extensions for cylinders 4 and 6 only.

From email a glowplug wire set is not availiable seperate from dealer. They only offer a new engine wiring harness or bits and pieces:

New engine wiring harness:
Part No. 15302442
GM LIST: $3,040.19
OUR PRICE: $1,802.23

gmpartsdirectdotcom

Whew for that kind of dough I would rather hack into the harness and build my own (or run some new loom). So definately going to try and use OE wires.

I'll see how it goes next week.

[Robyn]

They really know how to stick it to ya dont they.
I got a new harness for my engine when I rebuilt it. The one I got was the one that connects to all the sensors and the IP the listed for over $200 and The parts guy at the local chevy dealer made me a deal as someone had ordered it, opened the box and not taken it. They could not send it back to the warehouse so a deal was struck..
I am a stickler for neat and tidy under the hood and such. I dont really care for all the plastic plugs they use now as the suckers break so easily after they get some time on them. The weather pack connectors are fairly reliable as far as staying clean inside.

On my Hummer kit rig I am using all new virgin wire and running my own. All the wires that dont have to be connected to a factory plug of some sort will have crimped eye connectors attached to studs in the electrical panel.
I have scrounged a fairly nice engine harness and replaced all the weather pack connectors with new ones where I can.
Wiring is a pain no matter what you do. Keep it tied up properly and away from the heat and from rubbing on stuff and you will be fine.
Unless you have been having issues I think just a careful examination and maybe a new connector or two at the glow plug ends and you will be fine.

[jrsavoie]

To get the center ones off you need either the special tool to pull the wires or you do as I do and remove the nuts holding the heat shield and slide the shield back so you can unplug the wires. The right rear is a Bitch but doable from below. With a cold engine *****
Good luck
Robyn

Does anybody have a link to the special tool?

I tried Googling and this thread and one other were as close as I could get to any info on the tool at alll

[Robyn]

Those are GM tools and are going to be tough to get.

Just undo the nuts holding the shield on and then slide it down the wire.

Easy access with the RH front wheel off. Go through the access hole behind the rubber flap

[jrsavoie]

Those are GM tools and are going to be tough to get.

Just undo the nuts holding the shield on and then slide it down the wire.

Easy access with the RH front wheel off. Go through the access hole behind the rubber flap


I've got 6 of these 6.5's to work on. And they all need glow plugs checked. If the tool would save me some work it would be worth the search.

I usually do take the heat shields off. I bought high grade stainless nuts and found some heat shields. I use Kopper Kote on the heat shields and glow plugs.

If anybody has a part number for the tool I would appreciate it.
Thanks