Glow plug relay

[bongojoe]

Hi all — late 1999 2.5 TD struggling to start; it turns over for ages, cloud of smoke from exhaust before eventually kicking in. (Runs absolutely fine once started.)

Seems like a glow plug problem and noticed I no longer hear the glow plug relay click when the orange light on the dash turns off.

I have removed the glow plug relay behind the battery and tested it on a different 12v supply and it seems to be working fine — clicking on and off perfectly well. Have also tested the glowplug fuseable link from the starter battery and that is fine.

With the relay removed I put a meter across the black / purple wires that activate the relay and get no voltage when ignition turned (it does briefly jump up to about 4v but quickly drops back to 0v).

I have tested the 10A fuse shown here and it is also okay:



Any other suggestions of what I could check? Problem almost certainly stems from no activation power getting to glow plug relay.

Thanks in advance!

[g8dhe]

That tends to point back towards the ECU Have you had any work, especially welding carried out at all lately ?

[bongojoe]

Thanks Geoff. I had the sills welded to get through its last MOT a couple of months ago. This only started a few days ago, but I have been having intermittent problems with the van taking longer than usual to start for about a year.

If it is the ECU is that a big deal to repair / replace?

[g8dhe]

Replacing the ECU itself is quite easy, finding the right one can be a bit fraught as there seem to be a lot of versions! Just how they affect the engine/gearbox is difficult to say without trying - I suspect but can't prove that they will generally be quite happy for the correct type of engine, as the engines and gearbox's don't change much. But that is not a guarantee in anyway shape or form

[bongojoe]

I've found one on eBay for £40 that seems to be a match for mine — certainly cheaper than another trip to the garage so I think I'll get it and see if it works. (Can always resell if it doesn't.)

The seller has a disclaimer saying "This will need coded to your vehicle. The ECU has not been unpaired/divorced from the donor vehicle an auto electrician with knowledge of this can help."  — looks like something standard on all their listings, is that something I should worry about?

[g8dhe]

I suspect that won't apply for this age of ECU, rather its intended for more modern ones where there is greater interaction between the systems that run the engine/dashboard/car as a whole

[bongojoe]

That's what I thought — will let you know how I get on. Thanks again!

[bongojoe]

Replacement ECU arrived, switched it over (which was very easy) and same problem is there — but van otherwise seems to run fine.

Would it be sensible to trace and check continuity of purple wire from ECU to glow plug relay (assuming of course there is a direct connection)? If so, any ideas on where to find the wire at the ECU end? There does appear to only be one wire of the correct colour coming out of ECU — which I assume is the correct one — but disappears into a fat loom and no idea where it goes from there.

[teenmal]

Replacement ECU arrived, switched it over (which was very easy) and same problem is there — but van otherwise seems to run fine.

Would it be sensible to trace and check continuity of purple wire from ECU to glow plug relay (assuming of course there is a direct connection)? If so, any ideas on where to find the wire at the ECU end? There does appear to only be one wire of the correct colour coming out of ECU — which I assume is the correct one — but disappears into a fat loom and no idea where it goes from there.

Have you tried a direct feed to the glow plug/heater rail?

[bongojoe]

Fixed it.

I spent a lot of time checking voltage of purple wire at the ECU and continuity of wire through to the GP relay, all of which was fine — nice steady 12v when ignition on.

But still no voltage at GP. Then it occurred to me I hadn’t checked the black ground wire… bit of a ‘duh’ moment! There was no continuity between this and +ve terminal on battery or chassis.

So I pulled the spade connector out of the little white plug that goes into the relay and replaced it with a new one with new wire feeding to a wee lug that I connected onto the threaded post that holds the relay onto the chassis. That completed the circuit and all working fine now; healthy clicks from the relay and van starts immediately.

Anyone want to buy an ECU?

[Hazzobongo]

Glad you got it sorted, lecky problems are nearly always down to duff earths.