Citroen Relay - Glow Plug fault

[TB07]

Looking for advice on where to start. I am a fairly proficient diy mechanic and I also studied electronics at A-Level, thus I'm happy to take on many tasks to maintain my vehicles.

Citroen Relay 2007 - 2.2 transit engine. Purchased 5 years ago.
One glow plug was never working. No dash light, but OBD reader showed and a quick multimeter check at the relay showed one open circuit (left plug). Never bothered to investigate further. Coming up to this winter I noticed I now have two open circuit glow plugs, and the van was getting difficult to start. Time to replace the plugs.

Three plugs came out OK, the left plug snapped. With the right tools, I managed to remove this and replace all the plugs. Also the left plugs wiring had been disconnected intentionally, it seems, by the last owner?!

So far so good.

The problem.

When trying to start the van, the electrics go haywire as soon as the glow plug dash light comes on. If I disconnect the glow plug wiring harness, all is well. As soon as the glow plug harness is back on and I turn the key, something seems to short out. Faulty glow plug? Faulty wiring?

Any suggestions on where to start my investigation?

What resistance should my glow plugs be showing? Any other checks I should be doing?

Thanks for your advice!

[mickthemaverick]

As a start I'd suggest disconnecting one glow plug at a time and trying it. Hopefully you will discover which plug circuit is causing the problem which you can then investigate further.

[Mihael_M]

The resistance of the glaw plugs is 0.8 - 1.0 ohm if it is good.
Try to install one by one. If none of them work, then the Glow plug control module is faulty.

[TB07]

Thank you both.

I will look into this over the next week or so and see what I find.

Was aware of the glow plug relay, but not the control module.

So many parts to think of.

Thanks

[TB07]

I've now checked the resistance of the glow plugs at the connector on the left side of the engine.

All plugs read 1ohm

I cleaned the connection and cleaned the connection at the (brand new) battery.

I also checked the resistance of each glow plug at the relay terminals (approx 1.2ohn each).

Everything seems to check out.

Engine starts. No issue with electrics.

However, the OBD has thrown the code:
P0683 Relay, pre-/post-heating control

Not sure if the plugs are actually being turned on. Need a second pair of hands.

Will keep investigating. Perhaps someone has a suggestion?

[TB07]

Update,
Checked the Fuses.
Checked connections.

Then checked individual glow plug voltage at the harness.

When ignition is turned on, all glow plugs receive 12v for 20seconds or so.

If I start the van, the glow plug voltage remains 12v (actually 13v) for another 30sec or so.

So it seems the relay is working OK.

Fault code P0683 is still present!

Using Autocom the "relay, pre-/post-heating control" is showing as active or inactive as expected.

The engine is still a bit sluggish at starting, however I know the EGR is not working.

Any suggestions please? Should I worry about the P0683 fault? Any way to check the glow plugs are actually drawing current and working correctly?

[sar77]

Hello,
If you managed to measure the resistance of the glow plugs, it means that the glow plug circuits are OK. To make sure that they are working properly, you can use a clamp meter adapted for measuring constant current. Measure the current in the thick wire going to the glow plug relay.
Sarunas

[TB07]

Thank you Sarunas,

I did borrow a DC current clamp meter.

Each glow plug was showing 10A, with a total for the harness of 40A.

Is this a normal current draw for a 2.2l transit engine in a Citroen?

I then improved the connections at the battery terminals as well as the earthing strap on the engine.

After this I got 60A on the glow plug harness.

The Starter definitely turns better. Still takes a handful of revs to start the engine. I will check what errors I'm still getting.

[perfidus]

Yes the earthing strap between the gearbox and chassis has to be checked on regular basis on the Relay vans. Mine is newer but also found corrosion on lugs. It's about humidity/water coming from the windshield, bad water tightness of the engine hood right above the connection. I don't know why you still got the errors and why the engine starts with that delay.

[TB07]

Yes. I can't beleive Citroen, Fiat, Peugeot are happy to release a van with this design fault.

They claim the water ingress is "not a problem" .
It's not a problem as long as you scrap the van after 3-5 years.

I'm constantly resolving issues caused by, or made worse by the engine bay water ingress.