How do you replace glow plug controller?

[earnshae 0]

Hello, I believe the glow plug controller on my car is defective.It is delivering 10 volts to the plug even when the ignition is not engaged.Has anyone seen a good tutorial on how to locate remove and replace the controller?

[bilgladstone 13]

Do you mean that if the key is not in the ignition and the car is otherwise completely switched off, there is still 10v to the glow plugs?Bil

[Alex 21]

I assume 10V is with the glowplug connector removed? If so, no worries, most solid-state DC switching devices "leak" a tiny (really tiny) bit. Enough to register on a voltmeter, but only micro-amps of current can come through. To confirm, hook it to ground through a bulb, and you should see that voltage disappear.

[earnshae 0]

Do you mean that if the key is not in the ignition and the car is otherwise completely switched off, there is still 10v to the glow plugs?Bil

Yes the glow plugs stay 100% of the time, including when the car is running and when the key is not in the ignition.Didn't realize that was the case until I parked it overnight and found that it drained the battery as a result.I assume this is a fused relay or other similar problem in the glow plug controller.I was hoping to find a tutorial that would allow me to pull the controller so I could inspect or at least a picture that would show me what I am looking to remove.

[earnshae 0]

I assume 10V is with the glowplug connector removed? If so, no worries, most solid-state DC switching devices "leak" a tiny (really tiny) bit. Enough to register on a voltmeter, but only micro-amps of current can come through. To confirm, hook it to ground through a bulb, and you should see that voltage disappear.

When I came into the garage to find my battery drained I could smell burning silicone before I disconnected the battery.Given the smell and my above observations I would like to inspect the controller to see if any components have been damaged. I think at the very least there is damage to the control circuit which allows the glow plugs to remain on while the engine is running.

[tolsen 630]

I am just in the process of repairing a glow plug controller which exhibited same fault pattern as yours. It turned out one Mosfet power transistor inside the controller was burnt out and shorted. This transistor works as a solid state relay. Easy to replace on the Renault glow plug controller that I am working on. I assume the Smart controller will be similar as made and designed about same time as my Renault. Electronic parts are cheap and readily available. Getting my Mosfet transistors (ordered 10 as nearly same price as 1) from Hongkong and thereby saving a few pounds but may have to way wait a week or two.PS. All pins on the power transistor were shorted thereby permanently feeding glow plugs. No damage to rest of circuit board as protected by a 1kOhm resistor on gate connection.

[earnshae 0]

Unfortunately the board is too far gone for me.I found the controller thanks to a drawing from the dealer (attached) it is very accessible.Just follow the wiring channel from the glow plugs towards the passenger side. It is a small box held in place with 2 bolts (I think they were 10mm).Loosen them and remove the two cables.Upon inspection I found that the cable plug connected to the glow plugs and 12 volt supply had become very hot and melted inside the board had melted and damaged many components. I am just replacing the whole box and plug due to the damage.I think the root cause may have been frequently boosting the vehicle during the winter causing, over current conditions.Literally a 5min repair if you have the parts.Key symptoms smell of burning silicon, glow plug light stays on, glow plug codes on scan gauge, constant 10volts at glow plugs.If any one would like I can post pics of the inside of my nasty glow plug controller... it was so bad the screw melted out and were rattling around shorting things out in the box.

k_gze.pdf

[CANMAN 23]

How much did the new controller cost?Did you measure the resistance of the glow plugs?It's possible a defective plug could damage the controller.CANMAN

[Some Guy 0]

I think the root cause may have been frequently boosting the vehicle during the winter causing, over current conditions.

I would think it'd more likely be a faulty glowplug or damaged wiring responsible for drawing too much current. Although I suppose boosting could be a possible explanation. Normally when the glowplugs operate, they are running off battery - around 12 V. But when you boost from another vehicle that has its alternator running, voltage is around 14.4 V, so the glowplugs would indeed draw more current than usual. Hmmm.

And yes, photos of destruction are always a must!

Edited April 21, 2011 by Some Guy