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Engine Specific Info and Questions => IDI Engine => Topic started by: Alcaid on November 29, 2010, 12:17:52 pm

Title: Fast glow plug relay wiring diagram?
Post by: Alcaid on November 29, 2010, 12:17:52 pm
Hi,

right now I have a push button to active the glow plugs in my mk1 (1.1 -> 1.6td conversion). I'm putting in new glow plugs and I will go for the Bosch fast glow kit, but can anyone help me with a wiring diagram so that I can avvoid having the push button? Does it control glowing time based on the water temp sensor?

Thanks :)
Title: Re: Fast glow plug relay wiring diagram?
Post by: Vincent Waldon on November 29, 2010, 12:31:53 pm
Here's the wiring diagram for the relay socket... it will need to be connected to a dedicated coolant temperature sensor and the starter feed:

(http://i197.photobucket.com/albums/aa85/vwaldon/glowplugrelaypinout.jpg)

The coolant sensor tells it how long to stay on for, and the starter feed tells it to shut off as you attempt to start the car.

Note that it's intended to drive the fuel shutoff solenoid via pin 86... you won't need that line since you have obviously figured out a different way to power the solenoid as part of your swap.
Title: Re: Fast glow plug relay wiring diagram?
Post by: Alcaid on November 29, 2010, 01:15:56 pm
Vince, you are my hero!  ;D
Title: Re: Fast glow plug relay wiring diagram?
Post by: Alcaid on November 29, 2010, 01:36:35 pm
30 to battery constant 12V or key triggered 12V?
Title: Re: Fast glow plug relay wiring diagram?
Post by: Vincent Waldon on November 29, 2010, 01:41:18 pm
Constant... that's the full 40-60 amps that's going to the glowplugs.   ;)   10 gauge wire is a good idea for both 30 and 87.
Title: Re: Fast glow plug relay wiring diagram?
Post by: Alcaid on November 29, 2010, 01:49:26 pm
Ok, just thought it was a bit funny that if battery is disconnected and connected again the relay will glow the plugs. Not an everyday problem though ;)
Title: Re: Fast glow plug relay wiring diagram?
Post by: Vincent Waldon on November 29, 2010, 02:11:01 pm
Nope, you make a good point.

I've probably mis-led you with the label on terminal 50... the starter terminal... 'cause it's the trigger and the defeat.

It's "on" when the key is in the "on" position, and then iirc goes off when the key is moved to "start".... this tells the relay to stop glowing the plugs and allow full juice to the starter.

As least that's how I remember it working... don't have any MK2 schematics on my at the moment to confirm and it's been a while since I've had one under the wrench.

Will have a peek at my Bentley tonight... or perhaps someone with more recent MK2 experience with weigh in.

Title: Re: Fast glow plug relay wiring diagram?
Post by: Alcaid on November 29, 2010, 02:36:53 pm
Does indeed sound logical that terminal 50 is the trigger
Title: Re: Fast glow plug relay wiring diagram?
Post by: Otis2 on October 28, 2011, 02:06:20 pm
I'm having an odd issue with my glow plug relay, and thought I'd post it here because of Vince's very convenient diagram.

The relay seems to work fine, flashes up the plugs when cold, and turns them off again in a reasonable time.  Engine starts smooth, no problems to that point.

The issue arises if I rev the engine past 2500 rpm and the engine is still relatively cold.  At that point, the glow plug light will suddenly show that my plugs are back on, and it stays lit for about 3 seconds.

However, once the engine is up to temperature, no matter how high I rev it, the glow plugs do not switch back on.

I initially thought there might be a loose connection at the relay, especially the coolant temperature signal, that temporarily disconnected with vibration (ie. 2500 rpm) and then it re-established contact.  So I crimped the hell out of the connections and smeared with dialectic grease.  (This is a non-factory install, with female spade connectors attached to the relay, not the factory relay "seat").  However, this has not made any difference.  I suppose I should have foreseen that was not the cause, since the T signal *must* be getting through to the relay, since the issue never arises once the engine is up to operating temperature.

Anyone got any ideas what may be happening here? 

If I had a small air bubble in the coolant circuit, would the GP relay behave like this?  (I have no other noticeable coolant-related issues, so I don't *think* this is the issue, but it's a Vanagon converted gasser, so there's miles of coolant hose, so anything's possible.)

Here's the wiring diagram for the relay socket... it will need to be connected to a dedicated coolant temperature sensor and the starter feed:

(http://i197.photobucket.com/albums/aa85/vwaldon/glowplugrelaypinout.jpg)

The coolant sensor tells it how long to stay on for, and the starter feed tells it to shut off as you attempt to start the car.

Note that it's intended to drive the fuel shutoff solenoid via pin 86... you won't need that line since you have obviously figured out a different way to power the solenoid as part of your swap.
Title: Re: Fast glow plug relay wiring diagram?
Post by: rodpaslow on October 28, 2011, 02:16:44 pm
Doesn't the 'glow plug' light come on as well if the water trap (not too sure what to call it) just in front of the diesel tank has a problem like water or bad diesel?  People usually disconnect it.
Title: Re: Fast glow plug relay wiring diagram?
Post by: Otis2 on October 28, 2011, 04:32:53 pm
Thanks for the suggestion, but there's no water trap idiot light on this vehicle.

The issue is absolutely tied to engine rpm, which is why I suspected vibration as the cause. 

Revs of 2500+ rpm always turn the glow plug light on when the engine is cold.  It's just like clockwork.  But after the engine reaches normal operating temps, the light (and presumably the plugs) stay off, even beyond 2500 rpms.
Title: Re: Fast glow plug relay wiring diagram?
Post by: vanbcguy on October 28, 2011, 05:39:00 pm
I would start by focusing on the relay's ground connection - if it looses ground even momentarily it will cause it to reset.  At that point it will believe that you have just turned the key on and begin its cycle again.

Vince, how confident are you around the purpose of #50 and #86?  I don't have any Mk II wiring diagrams either, but I was under the impression that power at #86 told the relay the key was on, and power at #50 would tell the relay that the engine was being started, and to shut itself off.  I didn't think there was any power at the starter solenoid after starting? (well there is on the B+ terminal obviously)
Title: Re: Fast glow plug relay wiring diagram?
Post by: R.O.R-2.0 on October 29, 2011, 12:45:00 pm
Thanks for the suggestion, but there's no water trap idiot light on this vehicle.

The issue is absolutely tied to engine rpm, which is why I suspected vibration as the cause. 

Revs of 2500+ rpm always turn the glow plug light on when the engine is cold.  It's just like clockwork.  But after the engine reaches normal operating temps, the light (and presumably the plugs) stay off, even beyond 2500 rpms.

THATS F****** weird man.. ive never had my plugs change because of RPM changes..

something is not right.
Title: Re: Fast glow plug relay wiring diagram?
Post by: Otis2 on December 02, 2012, 02:46:43 pm
A follow up with the resolution:

My issue turned out to be a loose connection at the Terminal 50 wire on the starter solenoid.  The female spade connector just wasn't gripping the male tab tightly, although it looked fine to outward inspection.

So when I rev'd up the motor, the loose Terminal 50 connection at the solenoid would briefly break and re-join, probably within a fraction of a second.  But that was enough to "re-set" the relay. 

If the temperature signal was not reading hot enough at that point, then the relay would start a new glow cycle.  But if the temperature signal was already reading hot at that point, then I wouldn't have any notice of the temporary interrruption in the Terminal 50 wire signal. 

The result: multiple glow cycles with a cold engine, every time I rev'd the engine up, until the engine reached normal operating temperature.  At that point, the symptoms would always disappear.

Uggh.

Solution posted in the event this helps someone else.
Title: Re: Fast glow plug relay wiring diagram?
Post by: ORCoaster on December 02, 2012, 08:50:19 pm
I love it when OP puts down the final solution like this one.  This is the electric Gremlin of all times.  A loose connection on a running engine how you going to find that?  Run along side the car with a meter hooked up?  Glad you got it.  And yes IT does help to have this information.
Title: Re: Fast glow plug relay wiring diagram?
Post by: mtrans on December 03, 2012, 03:29:50 pm
x2
Title: Re: Fast glow plug relay wiring diagram?
Post by: Johndoh on September 14, 2015, 05:11:11 pm
I know this is an old thread however maybe someone can solve an annoying problem I have. I have a VW Polo SDI I'm trying to repair for an old lady. I don't think you guys have SDI engines it's basically a TDI without a turbo. Anyway I have no comms with the ECU and  no flow plugs working. I want to install a glow plug relay to do the job automatically but I'm not sure which wire from the CTS I should connect to the relay. Anyone know? Apologies for the long post and thanks.