Glow Plug Re-Wiring

Technical questions and answers concerning all models of VW diesel vehicles.

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Fatmobile
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Re: Glow Plug Re-Wiring

Post by Fatmobile »

I used one of those solenoids on my last build,.. without the extra ground.
I left out the fuse box this time.
I've had a few problems with fuse connections going bad from corrosion,.. posibly supposed to be used inside a car.
When I think there might be a bad glowplug;
I usually clamp my ammeter (cheapo dash-mounted analog style) to the battery and the other end to the power post on the fusebox,
then pull fuses until I find one that doesn't move the gauge.

On my new fuseless setup; I'll probably skip the meter and just disconnect wires and watch for a spark that indicates current flow.
'91 Golf gasser converted to a 12mm pump, M-TDI.
'84 1.6TD Rabbit with a VNT-15 turbo, still setup to run on vegetable oil.
'84 GTI with 1.7TD pistons and intercooled.
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fj40dave
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Re: Glow Plug Re-Wiring

Post by fj40dave »

Well....I got the Dasher started yesterday....a few bug's to work out including the glow plug system not working. :shock:
I've drawn a schematic of what I have, any thoughts or ideas are greatly appreciated!

Image
Image
TylerDurden
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Re: Glow Plug Re-Wiring

Post by TylerDurden »

I'd pull that coiled ground wire, pull the fuses and check for voltage at the solenoid output (should hear click too) with the key on.
Have a nice day.


'91 Jetta ECOdiesel TD - clean & complete (less motor/tranny) for sale

'82 Westy Vanagon 1.9 N/A - 23.5mpg
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Fatmobile
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Re: Glow Plug Re-Wiring

Post by Fatmobile »

Yeah, I'd pull the curly wire.
I still don't think that goes to ground.
I have almost the same solenoid and it's working great,.. I think that post is for power to something while the starter is turning.

What's the part about a wire going to fuse block power for the glow plugs?
Power for the glow plugs doesn't come off the fuse box,.. it's right from the battery.
In the Rabbit's anyway.
Oh wait the older one were plugged into the "H" section on the back of the fuse box.

Anyway, wonder what you are doing with that wire. Didn't see it mentioned in the illustation.
'91 Golf gasser converted to a 12mm pump, M-TDI.
'84 1.6TD Rabbit with a VNT-15 turbo, still setup to run on vegetable oil.
'84 GTI with 1.7TD pistons and intercooled.
2003 TDI wagon
2000 TDI Jetta.
fj40dave
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Re: Glow Plug Re-Wiring

Post by fj40dave »

Ok....I'ma gonna pull the green curly wire first thing tomorrow and see if that makes it better.

The other wire I mention went to the original fuse thing mounted on the side of the battery tray.....I had marked it "Batt + GP"......and it goes into the wire loom heading toward the drivers side (back to the fuse panel on the interior driver's foot well)....

If it's not toooo obvious yet.....I'm not much of an electrician :roll: ....I do really good with fire/medic stuff, and shade tree mechanic too....but that wiring stuff can befuddle me some :mrgreen:
82vdub
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Re: Glow Plug Re-Wiring

Post by 82vdub »

If you don't have voltage at the glow plugs when the system is calling for them, keep going upstream (electrical wise) and keep looking for the voltage and find out where it stops. There is also a temp sensor that when the wire is removed, it tells the glow plugs to run no matter what the temp is. Maybe the wire is connected to the wrong sensor, or the sensor is shorted out?
Everybody else lists their cars here - but not me.

I have too many to count
Vincent Waldon
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Re: Glow Plug Re-Wiring

Post by Vincent Waldon »

You should hear a pretty loud "clunk" when the solenoid engages... if not.. drive it directly with a wire from the positive battery terminal. No clunk... solenoid is defective or it is the type that does not ground internally to the frame. Try re-grounding it, as you have done originally, and see if you get a clunk.

Even better, if you have a multimeter you can also confirm that you read a few ohms between the two coil terminals on the solenoid... or between one of those two terminals and the metal frame of the solenoid.
Vince

Edmonton, Alberta, Canada
2001 silver TDI Jetta Malone Stage 1.5 , 2001 blue TDI Jetta SBIII 216s Malone Stage 3
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Gone but not forgotten: 1969/1971 Beetles, 1969/1974 Westies, 1979 Rabbit, 1986 TD Jetta, 1992 gas Jetta, 1994 TD Jetta

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fj40dave
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Re: Glow Plug Re-Wiring

Post by fj40dave »

No luck today getting it to work (no clunking or anything).....going to replace the solenoid - might have fried it initially....don't know. :oops:

Going with the momentary push button set-up too....then I will isolate the circuit completely and know exactly what's going on (in theory!)

:x

Update: Momentary switch works great - pic of the project after work this week... 8)
bbob203
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Re: Glow Plug Re-Wiring

Post by bbob203 »

Finally partially rewired my glowplugs last night. I added the e350 solenoid i bought a few months ago. Biggest reason i didn't get around to it until now was because i couldnt figure out a place to put it that didn't bug me. Last night i had an epiphany.. I noticed i still had one of the carriers in place for the power steering lines i took it off and it was the perfect place to put the solenoid no drilling just bolted it right up.. instant ground.
91 jetta gl na german built
91 jetta gl ecodiesel
ajbirken
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Re: Glow Plug Re-Wiring

Post by ajbirken »

I just got a 1989 jetta with a NA 1.6. It was having slow cold starts. My stock glow plug system wasn't getting any juice for some reason and I like a push button anyway. So I ran a push button setup to a self grounding ford-type solenoid (77 wagoneer since that was what I have around).

I did not us a fuse block and ran it directly from the solenoid to the bus-bar rather than individually wiring each glow plug.

The solenoid is upside down from how it would be in a wagoneer. I found a convenient place to mount it on a bracket for some device that I have no idea what it is (that is the coolant reservoir in the background)! Black wire to battery, red/white is stock wire to bus bar. thin red wire is to ignition on 12V source with a cheap 3 dollar push button.

Image

Can anyone see a problem with this setup other than I suck at wiring and used a crappy ring connector?

I figured my starter doesn't have a fuse and the glow plugs will never really be on any longer than I would run a starter.

Why run the fuses anyway? I am electrically challenged for sure and would love to be schooled

Thanks for any input/advice.

Adam
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Re: Glow Plug Re-Wiring

Post by vanbcguy »

ajbirken wrote:I just got a 1989 jetta with a NA 1.6. It was having slow cold starts. My stock glow plug system wasn't getting any juice for some reason and I like a push button anyway. So I ran a push button setup to a self grounding ford-type solenoid (77 wagoneer since that was what I have around).

I did not us a fuse block and ran it directly from the solenoid to the bus-bar rather than individually wiring each glow plug.

The solenoid is upside down from how it would be in a wagoneer. I found a convenient place to mount it on a bracket for some device that I have no idea what it is (that is the coolant reservoir in the background)! Black wire to battery, red/white is stock wire to bus bar. thin red wire is to ignition on 12V source with a cheap 3 dollar push button.

Image

Can anyone see a problem with this setup other than I suck at wiring and used a crappy ring connector?

I figured my starter doesn't have a fuse and the glow plugs will never really be on any longer than I would run a starter.

Why run the fuses anyway? I am electrically challenged for sure and would love to be schooled

Thanks for any input/advice.

Adam
I'm a little concerned about the proximity of that positive connection on the left to the metal bracket it is on - any chance that could touch? It is hard to tell from the picture!! If that shorted out, you would have a mega bad time.

The fuses are there so you don't burn your car down. If a glowplug fails in such a way that it becomes a dead short (which does happen!!), you will have burning insulation and smoke in about 15 seconds after engaging the glowplug circuit without fuses in place. Same if that terminal above shorted out on the bracket. Once insulation starts to burn/melt, it becomes very very easy for other shorts to happen, leading to more smoke, more fire and eventually a blackened hulk of a car. Fuses are a very very good thing.

At the very very least, run the power wire from the battery to the stock glowplug fuse and then to your solenoid. The stock fuse is known to fail though, so a 60A aftermarket fuse would be a better choice. That still won't help you identify which glowplug failed if one does short though, so 4 separate fuses is the best way to go.

Just to get a sense of scale for the amount of current your are running through your glowplug wiring - most houses up until about the 1980s had 60A service for the entire house. The voltage is higher, but the amperage is the same. Current (amps) is what drives the wire size requirement - the more current, the larger the wire you need. 60A is a LOT.
-Bryn

1994 Jetta with a 1988ish 1.6TD - Jezebelle Jetta
1994 Jetta - 1.8 Monomotronic - Gertrude Jetta
bgator
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Re: Glow Plug Re-Wiring

Post by bgator »

Just finished repairing a PO fuse block bypass and while fixin his/my problem, it dawned on me that there has to be a better way to do the fusing.

Came here..... low and behold........my answers. It's nice to have access to all the "been there done that" people around here. Thanks

I'm not going to do a full mod with the solenoid relay, just a new fuse block with individual wires for the glow plugs. I'll bring the relay into the circuit later if needed.
DavyG

[img][IMG]http://imageshack.us/scaled/thumb/94/gertrudet.jpg[/img]
[/img]

Gertrude
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jkuehn
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Re: Glow Plug Re-Wiring

Post by jkuehn »

Here's an article I've had for years (I did not write it) which I used and it works perfectly! Its a really good re-wire of the glow plug system that keeps the high current in the engine compartment and delivers more amps to the glow plugs, and fuses each one separately. I tried to attach the version with photos, but it's too big. Here is the text only version, below, and here is a link to the full document with photos on Google Docs. You don't need a google account. https://drive.google.com/drive/folders/ ... sp=sharing

Overview:
IMHO there are several weaknesses in the original VW IDI glowplug harness, including:
• the full amperage of the circuit (50 amps or so) passes thru the firewall and thru the connectors in the fuseblock
• the copper buss bar makes removing the glow plugs a pain since you have to completely remove the 8mm nuts
• the copper buss bar makes troubleshooting a pain since all plugs are connected in parallel
• the 50A fuse is prone to hairline fractures that takes out all your glowplugs
• the glowplug relay itself is *extremely* expensive
• the length and gauge of the factory wiring results in a reasonably significant voltage drop to the glow plugs... I've measured below 9V at the plugs when the battery was delivering 12.5V


Ergo, this design has the following features:
• el-cheapo garden tractor relay carries all the current and protects the contacts of the expensive glow plug relay
• all the heavy duty current travels via short wires in the engine compartment to minimize voltage drops
• all the heavy duty current travels via over-designed wire gauges to minimze voltage drops
• separate fuses provide individual protection and prevent all plugs from being disabled at once
• separate and easy-to-remove fuses make it quick to continuity or current-test each glow plug individually
• color-coded wires make it easy to trace which glow plug is which
• modified connectors at the glowplug allow removal without removing the 8mm glow plug terminal nut


Materials needed:
1. generic starter solenoid: I used NAPA #SME 701670 since it had the smallest form factor of anything NAPA carries *and* was the cheapest, but any generic starter solenoid that can handle 30 seconds of 50A duty will do
2. generic fuse block: mine came from Canadian Tire, but most automotive shops have them. I picked the long-glass style of fuse because IMHO it's easier to see when the fuse is blown
3. a length of 4 gauge wire: I found it cheapest to buy a low-budget set of booster cables
4. four lengths of 10 gauge wire.. each length a different colour
5. two lengths of 16 gauge wire.. each length a different colour
6. four 20A glass fuses
7. three 4 gauge copper lug connectors
8. four 10 gauge female spade connectors
9. four 10 gauge lug connectors
10. two 16 gauge lug connectors
11. 4 sheet metal screws to mount the solenoid and fuse block
12. solder
13. (optional) a bit of heat-shrink tubing if you like to dress the ends of your cables
14. (optional) 1/2" plastic loom for bundling the glow plug wires
15. (oprional) a bottle of liquid electrical tape if you like to minimize the number of bare live wires in your engine compartment



1. Construction:

1) Start by soldering the fuse block to a short length of the 4 ga wire, terminated with a 4 gauge lug as per the above picture. I solder all crimped connections *and* insulate with red heat-shrink to reduce resistance and keep out the elements.
2) Mount the new relay and fuse block in a convenient location in the engine compartment. The idea of this system is troubleshooting convenience, so pick a spot where you can get to the individual fuses easily. Also remember that these are live wires and terminals, so it's a good idea to locate them off to the side where they won't come in contact with wrenches and screwdrivers during routine engine maintenance. On my A3 the driver-side shock tower is perfect:


3) wire up the soleniod ground (green wire and lug in the above picture), the energize wire (orange wire and lug in the above picture which leads to the original wire that supplied the glow plug buss) and a longer length of 4 ga wire, terminated with soldered and crimped 4 ga lug connectors, which runs between the relay and the battery. I prefer to go all the way to the 13mm stud on the engine's starter solenoid as the battery feed... I find connections at the battery tend to corrode quickly, get in the way when serviceing the battery, and don't easily adapt to a big 4 gauge connector.
If you're doing this wiring because you're installing a diesel engine into a gasser chassis and don't want to mess with the original glow plug relay and harness you simply run the energze wire (orange in the above picture) thru the firewall to a pushbutton switch on the dash. The other termnal on the pushbutton goes to a source of power that's hot when the key is in the "on" position. Push the button for 5-30 seconds (depending on engine temperature) to activate the glowplugs.

4) prepare the 4 different-coloured lengths of 10 gauge wire with lug connectors on the end:

As you can see I've taken a lug connector and cut off one side. When installed correctly this circular shape will stay in one piece as the glow plug nut is tightened, but will allow the wire to be removed without having to fully remove the glow plug's nut. Why is this important ??!! Well, those 8mm nuts are not only an enormous pain to thread on and off in cramped quarters but also have a life of their own... they love to leap off and drop down into the most inconvenient hidy-holes, requiring you to spend hours with a magnet fishing them out and cursing the day you were born.

5) Attach the glowplug wires to each glowplug, orrenting the connector so that the opening wants to close as you tighten the glow plug nut:

6) Route the glowplug wires neatly thru the engine compatment (I'm a big fan of plastic loom) and terminate them on the fuse block with soldered-and-crimped female spade connectors:

You'll notice I've cleverly arranged the wires in order... number 1 glow plug at the top, etc. I've also added the fuses in this picture, and a layer of liquid electrical tape (the black gooey stuff) to the buss side to help prevent an electrical short

You're done !! It might end up looking something like this:

You'll notice a few extra wires in this picture... the wiring at the top of the picture is a feed to a 30A breaker for accessories including a fog light relay (the blue and yellow wires at the top).
Not shown is a wire from the fuse side of the new relay which to an LED on the dash... a HIGHLY recommended addition:

This yellow LED shows me that the glowplug relay is actually engaging the glowplugs (unlike the glowplug light in the cluster). The one drawback of this LED is that it won't tell you if a fuse is blown... you'd need to run 4 LEDs to do that, since there are four separate feeds. However, unlike the stock system where a blown fuse takes out all your glowplugs, if a fuse does go you will still be able to start pretty easily on the three remaining glowplugs. Someday I'll design a fancy monitoring circuit that traps blown fuses... I used to be an electrical engineer after all.

Questions / comments / suggestions for improvement welcome !!
Thomas M
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Re: Glow Plug Re-Wiring

Post by Thomas M »

I'm going to use alligator clips and 10AWG on all four. Although I might go for a nut on #4. The "pain in the arse nuts" are gone. The clips (for my model) are easily moved on and off with a set of long needle nose and hold quite firmly. I will run the 4 wires through a 4 way fuse block with 20 amp fuses and then gang the leads through a 50 amp to tractor/Ford relay.
:roll: 1991 Mk2 Jetta non-turbo, 1.6 Diesel, engine code ME, hydraulic lifters,
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Fatmobile
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Re: Glow Plug Re-Wiring

Post by Fatmobile »

I like the alligator clip idea.
I use an alligator clip on my glow plug tester and it handles all 4 plugs.
Even though it gets warm it should handle 1 easily.
I don't send them to separate fuses anymore.

I do separate them by bolting a piece of flat copper onto #4
It has 2 holes drilled into it
it bolts onto #4 along with the wire from glowplug #3.
The other 2 bolt to the other hole along with power from the ford starter solenoid.

The fuses got corroded in the engine bay. Got hot caused problems.
They were often the reason a glow plug didn't work, even when they weren't burnt out.

The original plan was to be able to figure out what glow plug is burnt out.
With the wires brought out separately from behind the pump they can each be checked.
'91 Golf gasser converted to a 12mm pump, M-TDI.
'84 1.6TD Rabbit with a VNT-15 turbo, still setup to run on vegetable oil.
'84 GTI with 1.7TD pistons and intercooled.
2003 TDI wagon
2000 TDI Jetta.
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