Glow plug light 320 CDI W210

[David Wilkins]

Hi All,
I've had the glow plug light come on after starting and stay on. Read about it here and went through them plug by plug - one was 0.1 ohm and 5 were about 0.5 ohm. So I replaced the 0.1 ohm with a new one (which measures about 0.5 ohm). But the indicator light still comes on after starting. I had a quick look at the contol unit on the passenger side front inner guard, and it does not seem to put power to all of the plugs. This seems to be telling me the control relay is st*ffed. Is that likely? It doesn't look like this unit is able to be opened, but I'm thinking it has blown a fuse?

Your thoughts appreciated !

Cheers,
David

 

[dieselman]

Probably the plug that went short circuit blew the output fuesable link in the relay. What brand of plug was it?

 

[Olivier]

Have you checked all the plugs again? One might have blow again?

 

[David Wilkins]

Hi - thanks for the replies! The glowplug was MB original, 110k miles and 9 years old. I've checked them all just now and they seem ok, at least not short or open circuited. I'm interested to find the "fusable link" - when I saw one was shorted I thought this might happen. Does it live inside the relay control unit & can it be taken apart to fix? Or do I have to buy a new unit...
Cheers,
David

 

[toby1]

I'd be intertested to know the outcome as I have precisely the same issue with the light staying on about 30 secs after start.

No problem with cold starting though.

 

[Olivier]

I don't know about your relay but I had pen the one on the E300TD.
The contact were dirty/ burned.

 

[Walter1]

Had the same problem a while ago. Glow plug light was on but went off after driving for a while. Car was due a B service. They told me they had to replaced one of the glow plugs and the link box you refer to, at the cost of £160-00, for the box alone. Fixed the problem in the end.

 

[dieselman]

The fusable links are in the control relay, visible in Oliviers first photo.

 

[David Wilkins]

Thanks All !
Problem now fixed. The 320CDI has the same relay box as shown in the pic (thanks Olivier) so I got out the knife and opened it up. Sure enough 2 of the links were blown. I formed replacement links out of about half inch of 30 amp fuse wire in the shape of the omega ohm symbal - how appropriate - and soldered them in. Then I changed all the glow plugs. Hey presto - light fixed and smoother starting. The glow plugs were from Euro Car Parts, about £10 +vat each and the fuse wire was about 50p. Sure beats replacing the control unit!

Cheers,
David

 

[dieselman]

Thanks All !
Problem now fixed. The 320CDI has the same relay box as shown in the pic (thanks Olivier) so I got out the knife and opened it up. Sure enough 2 of the links were blown. I formed replacement links out of about half inch of 30 amp fuse wire in the shape of the omega ohm symbal - how appropriate - and soldered them in. Then I changed all the glow plugs. Hey presto - light fixed and smoother starting. The glow plugs were from Euro Car Parts, about £10 +vat each and the fuse wire was about 50p. Sure beats replacing the control unit!

Cheers,
David

Nice fix.
When the new Denso plugs from ECP blew my relay i made them pay for a new one.

 

[Alex Crow]

it may have been said, but beru or bosch plug sare the ones to go for - avoid ngk and denso. the easy way to test the glow plug 'relay' is to do a continuity check between the output pins, they should all have continuity with each other.

 

[jonclancy]

E320 CDI W210 Glow Plug Relay - Light remaining on.

Just had the same problem. All glow plugs replaced and still the light remained. All but one of the old plugs measured OK (0.8 Ohm on my meter). I removed the relay (on the nearside front inner wing), making sure I did not earth the big positive feed to the relay (battery voltage, and I wasn't about to test the current draw!!).

If you strip out the potting compound, the relay housing clicks apart. Hey presto, one blown fusible link. I selected some appropriately sized fusewire, like David, and soldered it in place. I reassembled, including running a bead of sealant around the casework join.

Problem solved. I assume the link blew when the original duff plug went South.

It would be nice to obtain the fusible links. Despite the unit needing desoldering to get at them (not a problem with the right tools), it would be a cheap and proper fix, rather than shelling out a huge amount for a replacement and junking the old unit.

 

[sanjoy]

I had 3 out of the 6 had blown. Soldered some 30a fuse wire on there as per the this thread. Still getting the glow plug light after start. Short test drive started smokey then cleared up. Longer test drive needed.

 

[jonclancy]

Did you check the continuity either side of your solder joints to make sure there was not a cold joint?

If the light is still on, perhaps one of the plugs is duff?

 

[tjamesbo]

Did You change the Glowplug yourself ?? How was it ? I 'm led to believe extraction is risky procedure and there are techniques to minimise the risk on extraction
ie doing it warm / hot
Vibrating Tools ( Pardon me )
???????

 

[Mikimogo]

fixed relay but glowplug light still on!

What have I missed?
I have a Mercedes C220 CDI Auto estate W202 Yr 2000 (facelift model) same glow plug relay as your pics except only 4 cylinder so of course only 4 fuse links.

My glowplug light has been staying on for just about 1 minute after starting for the last month whereas it usually goes straight out on starting, I checked the resistance between the glowplug top and the engine and 1-3 were between .7ohms and 1ohm but number 4 was open circuit whereas when I checked it last week it was 1.3ohm. Intending to change the glowplug yesterday afternoon I went a run of about 6 miles to get the engine good and warm because the plugs are easier to get out warm and I had previously copper greased the threads on the plugs (because it had taken 3 days a couple of years ago to get the plugs out), on the last couple of miles the light came on and stayed on. After finding this thread and then eventually finding the Glowplug relay (under the washer bottle!) Put Carsoft Fault code reader multiplexer on my laptop and ran a CDI test, result was: fault code 1482 = preglow output -----> EPC control light does not light, ------->preglow light lights until the problem disappears, ---> pin setup: :1 ground; 2:communication; ( don't know what the pin thing is for!)


1) Changed bad No4 glowplug but light still on.
2) opened up the relay and repaired the fused link to number 4 glowplug
3) checked the repair for continuity.
4) checked the spade connectors in the plug, all had continuity with each other which I believe is correct,
5) checked continuity between each pin of the output plug and each of the glowplug top connectors all had continuity and resistance of around .8 to .9 ohms resistance.
6) re-assembled relay and tried it but glowplug light still on.
7) re-checked resistance between tops of glowplugs and engine and all were reading between .7 and 1.0 ohm.
8) Put my carsoft code reader on my laptop into diagnostic socket and checked but still reading fault code 1482 = preglow output -----> EPC control light does not light, ------->preglow light lights until the problem disappears, ---> pin setup: :1 ground; 2:communication; ( still don't know what the pin thing is for!) Aahhh it's just saying what pins are being used on the 38 pin diagnostics socket for this test.
9) Yep light still on!

Could one of the other glowplugs be faulty even though their resistance reads ok between the plug top and earth though I wouldn't have thought so. Am I wrong.

Any advice would be greeeeeaaatly appreciated. I use my car for PRIVATE HIRE and its got a plate test tomorrow so it looks like thats a fail, I've been on it until late last night and all day today to no avail. What have I missed?

 

[David Wilkins]

Hi Mick - I did have to go through the routine a few times. I suspect that at least one more glowplug is setting off the relay. If you have had one plug fail then , like a pair of shoes the others might be as well. I ended up replacing all glowplugs (Eurocarparts) and resoldering the relay at least twice. If this doesn't work then you may actually need a new relay. It just annoyed me that MB had designed the relay so that the first issue with the glowplugs meant you had to throw it away. Good luck !

 

[jonclancy]

Yup,

I had all my plugs changed as well. I had the same symptoms you have, Mick.

 

[undeckedhomer]

i had the same it was the glow control bow £60.00 fixed

 

[Mikimogo]

What have I missed?

Thanks guys for answering,
I've been on it again all day i have repaired the No:4 glowplug link in the relay 5 times, even though I have replaced the bad glowplug and all plugs read ok for resistance when I start the engine after about 3 seconds the No:4 link blows again and the lights stays on. I cant find any short which seeing that it is blowing the link would usually indicate, but one thing I have noticed it isn't actually breaking the 30amp wire that I've soldered across the breach it's blowing at one of the solder joints. I have made sure that the solder joint is strong and goes completely round the remaining link not just on the top for strength (has good continuity)and it is a goog strong solder joint but it doesn't just pop it open it blows it a good 4mm open. I have even vacuumed the relay in case a bit of solder or the original link shrapnel was floating about some where out of view and shorting but there is no short showing in any of the leads (from relay to plugs )but after it has blown the link when I start it again although I can't see a spark I can sometimes hear a quick crack and then it carries on running. Or are these just symptoms that the relay is beyond hope as when I clear the 1482 preglow output fault code as soon as I start it it's back again.
By the way what is the Glow control bow?

Thanks in advance for your input.