HORRIBLE electrical problem - glow plugs / Module. Calling all clued up folk...

[dann2707]

So I am having an issue with my mk4 1.5 dci clio. This thread is going to be pretty indepth tracing wires so not your usual "change this" thread.

Specifically when its freezing the car struggles to start and can sometimes take 7 attempts and I am getting a glow plug open circuit fault P0670.

So far I have changed the glow plugs and the module for new units...

I will show the wiring diagram so you can see the circuit which i've annotated but will also include a blank version too at the bottom.

On the module the pins are as follows:

1 - To glow plug
2 - To glow plug
3 - Signal Wire
4 - 12V incoming feed
5 - Ground (Switched ??????)
6 - To glow plug
7 - To glow plug
8 - Diagnostic wire

The glow plugs are earthed through the engine block.

I will talk through what I have done so far to diagnose... All things i've tested with a glow lamp to put load on the wires. (Anything in brackets shows what i'm testing)
Below are numbered points nothing to do with pin outs:

1 - Checked the incoming 12v feed from fuse box to glow plug module.. all okay and getting 12v. (confirm any breaks in cable)
2 - Loaded up signal wire from the ECU to the glow plug module, all okay (confirm any breaks in the cable)
3 - Loaded the diagnostic wire from ECU to the glow plug module... all okay (confirm any breaks in cable)
4 - The purple wire below goes to the camshaft position sensor, this looks to be a switched earth as its not currently an earth when probing it? This has confused me. Why would it have a switched earth AND a signal wire? Is this normal in auto electrics? I load tested that wire too, from the ECU to the glow plug module and not breaks in the wire but this one has me baffled a bit. This wire is proper thick coming out the module too, but then goes to a really thin ecu wire???? Thats not earthed as standard? To me that doesn't make sense but does stack up with the wiring diagram.
4 - Checked the earth from engine block to chassis, loaded up and all okay (check condition of ground)
5 - Despite glow plug module getting 12v feed, i've removed the main 70a fuse and cleaned it all up on the contacts (confirm good connection)
6 - Put a DC current clamp meter on glow plug wire AND main bulk of all glow plug wires and can confirm no current at all during starting.
7 - I have not checked the glow plug individual cables from the module. I just thought about this whilst having my tea but very unlikely as I have already clamp tested the bulk of the wires and absolutely nothing.


I feel pretty f**king defeated I won't lie and can't think what else would be causing this issue.

For what its worth, it comes up as a pending fault, and then turns to a full blown fault.

If anyone has any ideas on what to try next i'd be all open to any suggestions please! I feel like i've been really thorough but i'm clearly still missing something...

More of a close up without my drawings.

 

[Scrooge]

It’s been a long time since I played with a dci but usually even glow plug fault and slow starts are injector issues.

Before you go too mad with everything else I’d check they’re all good

 

[Brigsy]

Stinks of airleak at filter/primer or injector on its way. Do a leakoff test

 

[dann2707]

Cheers chaps, I've got a leak off test kit to try next but avoided it because of the glow plug fault code and how they're not heating at all.

It only struggles when its freezing too so all things to me are pointing to glow plugs.

 

[npt]

Presume all codes have been cleared after fitting new glow plugs, if all are dead when cranking then its likely a grounding issue from the ecu, got to be sure all plugs are good and no broken wires...wiggle wiggle wiggle, renaults are shite, sell it 😂

 

[Scrooge]

My little brother drove his dci everyday with no glowpugs connected for about 5 years. It always started ok apart from the two times the injectors went

 

[Brigsy]

Both of mine have glowplug faults stored. Defo none working on my blue one, fires off no issue -5 temps.

Log fuel pressure when cranking on diagnostics.

 

[npt]

It should really struggle if not impossible to start if no glow plugs are working at that temps

 

[dann2707]

I've got a picoscope kit I bought years ago and never used so just ordered some probes for it so I should be able to log a lot of things now at a decent frequency. My handheld reader is pretty basic.

I'll get a leak off test done ASAP too, probably tomorrow!

Whilst I agree it definitely could be injectors I can't leave that it only happens when it's freezing and I'm definitely getting no heat to the plugs

 

[Flob]

I can't help because diesels are the devils work.

What is the function of pin k3 on the ecu. The pin which is connected to both camshaft position sensor and the glow plug module? Is this supposed to be the signal line from the cam sensor or is this sensor 5v/gnd?

The Cam sensor likely is a hall effect and has 3 pins. Signal (square wave), power (5v), GND. It could be that the glow plug module looks at this square wave out of the sensor as a way to know the engine is running. This would also explain why you don't see power or gnd on that wire.

Do you have an oscilloscope to probe pins 8 and 3 on the module? EDIT* just read about your picoscope. From what I read the module needs a wake up signal from the ecu, I would guess this comes on pin3?

 

[Flob]

Have you checked the timing by the way bud? @Speedo Gonzales has the specs.

 

[Speedo Gonzales]

Has anyone consulted @Trainerbrow ?

He might have an idea

 

[dann2707]

I can't help because diesels are the devils work.

What is the function of pin k3 on the ecu. The pin which is connected to both camshaft position sensor and the glow plug module? Is this supposed to be the signal line from the cam sensor or is this sensor 5v/gnd?

The Cam sensor likely is a hall effect and has 3 pins. Signal (square wave), power (5v), GND. It could be that the glow plug module looks at this square wave out of the sensor as a way to know the engine is running. This would also explain why you don't see power or gnd on that wire.

Do you have an oscilloscope to probe pins 8 and 3 on the module? EDIT* just read about your picoscope. From what I read the module needs a wake up signal from the ecu, I would guess this comes on pin3?

So according to Chatgpt it's a clean reference ground that's going to the camshaft sensor mate.

The other two wires appear to be a signal wire and then the reference checking wire bud.

 

[dann2707]

Pin 8 = control
Pin 3 = diagnostics
Pin 5 = cylinder sensor

According to official wiring diagram

So that sounds plausible what you just said @Flob about it detecting engine moving.

If that's not getting a signal from camshaft sensor I wonder if that could be related.

 

[Flob]

Pin 8 = control
Pin 3 = diagnostics
Pin 5 = cylinder sensor

According to official wiring diagram

So that sounds plausible what you just said @Flob about it detecting engine moving.

If that's not getting a signal from camshaft sensor I wonder if that could be related.

Keep in mind I made that up, its a complete guess.

I would carry on once you have your probes. But I wouldn't rule out the fact that the car might have two issues. The glow plugs being one and an injector going bad. With either working fully seems they should still start alright going by Scrooge and Brigsy's messages above.

PS - if my guess is anywhere near correct then its more likely the module uses the signal from the cam sensor to turn off plugs once engine is running. Why it would need to do this when it has a control line from the ecu I don't know - so equally it could be a reference ground. Would be good to see a list of ecu pin functions of you have access to that to confirm that pin k3 is expecting.

 

[Flob]

Small amount of googling suggests that Black is ground, Green/White is signal and Green brown (Yellow in my screen grab) is a 5V reference

that will be easy to confirm by probing the cam position sensor, should be able to find 5v and gnd then the last one (which I think goes to the glow module) does look to be the 5v square wave signal out of the hall effect cam sensor.

 

[Flob]

If its a new glow plug module, new glow plugs and you have tested the continuity of all the wires you have to then start to suspect the ecu may have a fault or the new glow plug module is wrong. Your scope will likely answer that question.

 

[npt]

Ground it using an old bit of wire and see if it gets power through the clamp, just give it a quick buzz, if it works then thats the issue

 

[Cub.]

The conch of power has been blown.

Assemble, Nerds. x

 

[Flat Eric]

The conch of power has been blown.

Assemble, Nerds. x


View attachment 1773827

I like how nerdy the opening sentences are. "Going to be an in depth wire tracing thread" not your typical "change this" thread.

First few posts.

Check/Change Injectors.
👌

And rightly so! 👀

 

[dann2707]

Ground it using an old bit of wire and see if it gets power through the clamp, just give it a quick buzz, if it works then thats the issue

Good idea.

What I don't understand is do I still need the signal wire?

So I'll ground the big black wire but also need pin 8 activated as that's the signal wire. I don't know what that should be in terms of voltage

 

[Trainerbrow]

Has anyone consulted @Trainerbrow ?

He might have an idea

Nah, my glowplug controller is fucked. Chugged like a reyt b*****d the other cold morning.

 

[leeds2592]

Injectors I think bud

 

[Mr Trailer Man]

This any use?

https://www.elektroda.com/rtvforum/topic3293667.html

The guy had what looks like the same issue.

Solution is roughly translated from Polish: As it turned out, the fuse 70 burned in such a strange way that the current showed on the unfastened relay and at the start as the genie the contact cleaning disappeared and replacing the fuse did the trick. Thank you all for your interest in the topic and attempts to help solve the problem. I close the topic.

 

[dann2707]

This any use?

https://www.elektroda.com/rtvforum/topic3293667.html

The guy had what looks like the same issue.

Solution is roughly translated from Polish: As it turned out, the fuse 70 burned in such a strange way that the current showed on the unfastened relay and at the start as the genie the contact cleaning disappeared and replacing the fuse did the trick. Thank you all for your interest in the topic and attempts to help solve the problem. I close the topic.

Thanks mate. I changed that fuse the other day however I did just seen something on a dacia forum where that terminal was loose.

There's some paint overspray inside the fuse box from when the car was repaired so it's clearly had some interaction in there!

I shall take it off tonight and have a look inside it. Thank you dude.

Tricky one this!

 

[leeds2592]

Tricky one this!

It’s not, it’s your injectors

Spoiler

im sorry, I’ll stop now

 

[Flob]

Good idea.

What I don't understand is do I still need the signal wire?

So I'll ground the big black wire but also need pin 8 activated as that's the signal wire. I don't know what that should be in terms of voltage

Ground what?

 

[dann2707]

Ground what?

Not sure if you're being silly or being helpful 😂

 

[npt]

Good idea.

What I don't understand is do I still need the signal wire?

So I'll ground the big black wire but also need pin 8 activated as that's the signal wire. I don't know what that should be in terms of voltage

Signal wire shouldn't matter if testing ground, we're just trying to prove if grounding is the issue, if it still doesn't work then check signal wire, as its maybe not sending a signal/voltage from the ecu through the relay if ones fitted. Somewhere in the system there is no signal being sent, its either the ground, signal wire or ecu, I'd say its one of them 3, good luck

 

[Flob]

Not sure if you're being silly or being helpful 😂

No I'm being serious, the unit is grounded through the mount right? There is no ground wire on the pinout.

Signal wire shouldn't matter if testing ground, we're just trying to prove if grounding is the issue, if it still doesn't work then check signal wire, as its maybe not sending a signal/voltage from the ecu through the relay if ones fitted. Somewhere in the system there is no signal being sent, its either the ground, signal wire or ecu, I'd say its one of them 3, good luck

I think Dan has already tested for 12v at the unit so the relay is working. I don't think the signal wire is going anywhere near a relay?

Maybe the main relay somewhere which is ignition driven, the glow plug module is given V+ via a 70A fuse in the diagram above. It should be grounded via its mount (so worth checking it has ground agree).

It then has 8 pins. 4 are for the glow plugs which themselves are grounded via the block. Then 1 V+ wire, and 3 data type signal lines. One is for diagnostics, one is for ecu signal (probably a PWM waveform which I think might be missing) and 1 which oddly seems to be coming from the cam sensor signal pin.

So yea I agree its one of those 3 things, but saying its either a ground, signal or the ecu is like saying the problem is either under the bonnet or in the boot.

 

[dann2707]

As far as I'm aware the module isn't earthed to chassis as it's bolted to a plastic cowling and it's not on the electrical drawing

It's 8 wires in total.

12v in
Glow plug
Glow plug.
Glow plug
Glow plug
Weird earth that goes to camshaft sensor
Diagnostic line
Signal line.

 

[Brigsy]

I believe a single bad connection to a glow plug will fire this code. Check the individual wires to each.

 

[Brigsy]

It should really struggle if not impossible to start if no glow plugs are working at that temps

Just diesel knocky/bit of reek out the back. From reading the literature im sure you only get 3 seconds of heat on these old delphi commonrail unless its something daft like -10 which will give more. Its had one plug 100k ago, only ever failed to start when fuel pressure sensor failed.

Unlike the old mechanical diesels which took about 30 secs of cranking with no heat

 

[npt]

No I'm being serious, the unit is grounded through the mount right? There is no ground wire on the pinout.

I think Dan has already tested for 12v at the unit so the relay is working. I don't think the signal wire is going anywhere near a relay?

Maybe the main relay somewhere which is ignition driven, the glow plug module is given V+ via a 70A fuse in the diagram above. It should be grounded via its mount (so worth checking it has ground agree).

It then has 8 pins. 4 are for the glow plugs which themselves are grounded via the block. Then 1 V+ wire, and 3 data type signal lines. One is for diagnostics, one is for ecu signal (probably a PWM waveform which I think might be missing) and 1 which oddly seems to be coming from the cam sensor signal pin.

So yea I agree its one of those 3 things, but saying its either a ground, signal or the ecu is like saying the problem is either under the bonnet or in the boot.

Im not 100 sure tbh, but all 3 would need to be checked, the ground could be through the cam sensor then back to the ecu, this could be a signal wire also, its french after all..worst electrics ever which share s**t that others dont to save money, even the newer stuff is dog s**t to diagnose, same fault code for a whole s**t load of faults, they are shite 😂

 

[Flob]

As far as I'm aware the module isn't earthed to chassis as it's bolted to a plastic cowling and it's not on the electrical drawing

It's 8 wires in total.

12v in
Glow plug
Glow plug.
Glow plug
Glow plug
Weird earth that goes to camshaft sensor
Diagnostic line
Signal line.

This changes things 😂

But remember the supply is from a 70A fuse, so the return (ground/earth) needs to be able to carry 70A, this isn't going to be a pissy wire going back to the ecu.

 

[dann2707]

This changes things 😂

But remember the supply is from a 70A fuse, so the return (ground/earth) needs to be able to carry 70A, this isn't going to be a pissy wire going back to the ecu.

That's what's confusing mate. Because according to the wiring diagram, it goes directly to the pin 2 on cam sensor if you look up at my wiring diagram. This wire is f**king tiny thin as you've expect.

The wire then goes to the ecu from there

What doesn't make sense is how thick that wire is coming out of the glow plug module. I can't get my head around how its going from there to two tiddly little wires to cam sensor and ecu. There is a splice denoted in the other wiring diagram I have but to me it doesn't make sense.

Not sure what you said is correct though mate as the 70a will be feeding glow plugs, which is then earthed through the engine block and back to the battery with a thick earth cable?

 

[Flob]

That's what's confusing mate. Because according to the wiring diagram, it goes directly to the pin 2 on cam sensor if you look up at my wiring diagram. This wire is f**king tiny thin as you've expect.

The wire then goes to the ecu from there

What doesn't make sense is how thick that wire is coming out of the glow plug module. I can't get my head around how its going from there to two tiddly little wires to cam sensor and ecu. There is a splice denoted in the other wiring diagram I have but to me it doesn't make sense.

Not sure what you said is correct though mate as the 70a will be feeding glow plugs, which is then earthed through the engine block and back to the battery with a thick earth cable?

Yes you're completely correct. I've had two pints and as much as this will surprise many - I am not a large human. The majority of current will be going to the glow plugs and they are grounded to the engine block via the main earth strap, only a very small portion of current will be used by the module itself.

Whats the part number of the glow plug module?

 

[dann2707]

Did a bit more tonight in the very little time I had.

Checked resistance of signal, earth and diagnostic cable and all absolutely spot on. This was from ecu to glow plug module so I'm starting to rule out that.

Whether it's just not getting a signal now I'm swaying towards (need to check this next). I don't think I can really go and do much more without testing this now as npt said.

- Checked individual glow plug wires from the module to the glow plugs. All reading absolutely spot on.

- Checked under the fuse box, one slightly damaged wire so I repaired that but I don't think it was related at all.

 

[dann2707]

Yes you're completely correct. I've had two pints and as much as this will surprise many - I am not a large human. The majority of current will be going to the glow plugs and they are grounded to the engine block via the main earth strap, only a very small portion of current will be used by the module itself.

Whats the part number of the glow plug module?

It's this one mate

Genuine Renault Glow Plug Relay, 110678071R, for Renault, Nissan, Infiniti | eBay UK

Find many great new & used options and get the best deals for Genuine Renault Glow Plug Relay, 110678071R, for Renault, Nissan, Infiniti at the best online prices at eBay UK! Free delivery for many products!

ebay.us

 

[Flob]

Yea you need to wait until your scope probes arrive to see if the ecu is sending anything to the module.