[Engine] 2002 DW8 ECU glow plug relay issue (not starting)

[John Brock]

Hi everyone


I've been having problems  since weather got colder in the autumn .
 
Testing for voltage  on glow plug rail with multimeter identified  plugs
were not getting juice from  the relay.  The   dash glow plug light comes  on and
stays  lit for between 10-15 seconds as normal.  I replaced the relay and
it was fixed for a while.
 
The problem has returned .
After hours of tinkering, watching YouTube experts and jumping glow plug rail cable from battery every morning,
 I gave up trying to troubleshoot ,cursed myself for buying cheap parts, ordered another relay and replaced the glow plugs for good measure.


This time though  replacing relay didn't fix it.
 
I disconnected the relay output  cable from glow plug rail with the ignition turned on, and  checked voltage at  output terminal on the relay.
= 12 volts for approx 60 seconds before switching  off.

I repeated the test several times and found that  touching  the glow plug
terminal with the  output wire from the relay  after it  had opened  and
outputting 12v= switched relay  off immediately.


Thinking  perhaps it wasn't the relay at fault I took a gamble on a used
ECU  off e-bay , I hooked it up and the engine started   . Bolted it
to bracket and it didn't work again . I spent this afternoon  down the rabbit
hole  of looking for  damaged  wiring in the harness which I thought may
be shorting  something out and causing the relay to turn off under load.

I have checked the small relay with red sliding connector under ECU which 
looks ok The  connection was  tight  but  cleaned with switch cleaner anyway and
same with  the  adjacent round connector assembly which again looks fine


Testing the 5 pin Relay plug from ECU   I have the following readings on turning the ignition key 

 
pin 1 - earth
pin 2 n/c
pin 3  12v
pin 4 0.4v
pin5 9.5 v

 Guessing what is causing the relay to switch off under load  has something to do with feed to pin 4

 

Does anyone have any suggestions before I give up  and spend next Sunday  doing  Nick's  manual push switch in the cab ECU bypass mod ?  



Thanks in advance  

John

[Sol]

I don't know if your M49 relay is the same as the M59 but here's what I know from when I was testing my first Berlingo van (was an HDi though)

This is the pinout of the relay. 3 & 8 are the coil, 3 is 12v from the ECU and 8 is ground, but ECU keeps it floating if not required to be on. Pin 4 is 80A supply from main fusebox, this fuse is hidden below the top layer, inside the fusebox base.

pin 4 will automatically be connected to pins 1,2,6 & 7 when the ECU operates the relay.

[John Brock]

I don't know if your M49 relay is the same as the M59 but here's what I know from when I was testing my first Berlingo van (was an HDi though)

This is the pinout of the relay. 3 & 8 are the coil, 3 is 12v from the ECU and 8 is ground, but ECU keeps it floating if not required to be on. Pin 4 is 80A supply from main fusebox, this fuse is hidden below the top layer, inside the fusebox base.

pin 4 will automatically be connected to pins 1,2,6 & 7 when the ECU operates the relay.

Hi Zion ,

Thanks for speedy reply though iI think relay in my vehicle is different to your old one . It's a 5 pin connector (only 4 connected) with 2 brass terminals. I spent a couple of hours going through glow plug threads and learned that if  one of the plugs is shorting or harness grounding  the relay turns  off . I doubted whether this was my problem because the engine starts  hot wiring glow plugs from the battery.
This morning having run out of ideas I decided to check anyway.

I removed the air intake , detached the glow plug rail and reconnected plugs one at a time, checking  that the relay was staying on and 12 v getting to the plugs. I noticed that the last connection had frayed with bare copper wires sticking out from the insulation. Although they were not touching engine block I guessed 12v at 80Amps  wouldn't have too much difficulty arcing across a few mm.
I wrapped  several turns  of insulation tape around the last terminal  checked again and  relay worked as normal   Now just need to find  (or build) a new harness.

[Sol]

Great stuff. I'm sure if you can get to a scrapyard it would be possible to strip the harness out for a few quid.

[kerlaan]

I just had a problem with glow plugs.  I received 4 new ones from a reputable supplier.  After a couple of starts their resistances were all measuring 3 to 4 MΩ's.  There was no way the things would ever glow.

Today I fitted 4 new BERU GN016's (which all measured between 0.8Ω and 1.7Ω).  Not surprisingly the van burst into life as it should.

I too had been checking bad earths, changing the loom supply to the plugs, check both relays and ensure connections to ECU were dry and good.  Even that the loom plugs had no broken connectors.

My lesson is to not assume new glowplugs are new and or/reliable.  Grrr.

[oilyrag]

I don't know if your M49 relay is the same as the M59 but here's what I know from when I was testing my first Berlingo van (was an HDi though)

This is the pinout of the relay. 3 & 8 are the coil, 3 is 12v from the ECU and 8 is ground, but ECU keeps it floating if not required to be on. Pin 4 is 80A supply from main fusebox, this fuse is hidden below the top layer, inside the fusebox base.

pin 4 will automatically be connected to pins 1,2,6 & 7 when the ECU operates the relay.

Hi Zion ,

Thanks for speedy reply though iI think relay in my vehicle is different to your old one . It's a 5 pin connector (only 4 connected) with 2 brass terminals. I spent a couple of hours going through glow plug threads and learned that if  one of the plugs is shorting or harness grounding  the relay turns  off . I doubted whether this was my problem because the engine starts  hot wiring glow plugs from the battery.
This morning having run out of ideas I decided to check anyway.

I removed the air intake , detached the glow plug rail and reconnected plugs one at a time, checking  that the relay was staying on and 12 v getting to the plugs. I noticed that the last connection had frayed with bare copper wires sticking out from the insulation. Although they were not touching engine block I guessed 12v at 80Amps  wouldn't have too much difficulty arcing across a few mm.
I wrapped  several turns  of insulation tape around the last terminal  checked again and  relay worked as normal   Now just need to find  (or build) a new harness.

A great result - persistence paid off. Might a couple of layers of heat shrink tube be at least a decent temporary repair, that might then become permanent? 

[John Brock]

Scrapyard  trip a no no at the moment   due to Covid-19  . No  compatible looms on e-bay either.   I  took the van out for a spin  and  let it stand  for a couple of hours before  trying  a cold  start this evening.
Noooooooooooo.
 
When it was starting,  resistance through loom back to earth was 8 ohms. I  measured resistance again,  2.4 ohms same as from engine block  back to battery, so it's shorting out again.
I'll try insulating  around  frayed connection  with hot glue    rather than electrical tape  ,which already looks like it's coming off, fingers crossed it will last until I can  find a loom, otherwise back to hot-wire.

[kerlaan]

Scrapyard  trip a no no at the moment   due to Covid-19  . No  compatible looms on e-bay either.   I  took the van out for a spin  and  let it stand  for a couple of hours before  trying  a cold  start this evening.
Noooooooooooo.
 
When it was starting,  resistance through loom back to earth was 8 ohms. I  measured resistance again,  2.4 ohms same as from engine block  back to battery, so it's shorting out again.
I'll try insulating  around  frayed connection  with hot glue    rather than electrical tape  ,which already looks like it's coming off, fingers crossed it will last until I can  find a loom, otherwise back to hot-wire.

I feel your pain John, especially since I bought the last available loom on eBay 3 weeks ago.

As an idea, could you strip a length of 13 amp 3 core cable, pull the cores out and persuade the sheath over your loom?  A gentle filing of the loom attachment end with a file to help get it through would help.

And don't assume your glow plugs are good.  I am still upset at the 4 I had which individually measured 3 to 4 MΩ resistance.   Yet measuring through the loom to earth WAS similar to your 8Ω.  I still don't understand why.  But the new BERU GN016's (which for me on Amazon france were €8.50 each delivered) worked perfectly.

Good luck.

[jj9]

Just make a new glow plug cable, instead of making it in one piece just make 3 small cables with crimp on ring terminals, you'll get the wire and the terminals at any auto parts place.

.

[John Brock]

Hi jj9

Thanks for suggestion
I made a short one to replace  the  frayed  connection this afternoon  out of 3 core 13 amp cable.  I stripped and twisted 3 cores together  = 39 amps and  soldered around a 10 mm washer, insulated stub of exposed  wire with
a blob hot glue  and screwed down over the original  ring. It's not pretty but it doesn't short and with the new glow plugs   the van starts  1st time with no throttle. I'll get round to making a proper loom  ..one day