Hi,

Am I right if I do the following test :
assuming that my glowing plug relay is out of order, taking 12volt directly from the battery-red to ONE of the glowing plugs in the line should make them ALL glow and after a certain time (15 seconds.. ?) cranking should start the engine ?
Thank you in advance.

(excuse my English)

 

if they are like a mercedes glow plugs setup wired together in line then yes you could try that. i think if i were doing that i would try to use
a separate battery or jump box to run the glow plugs, if it was available. 15 seconds should be plenty of time to heat the plugs.

 

Thank you,
Yes plugs seem to be linked together, I've done the test with the car's battery (unfortunately I do not have another battery available right now) , and It doesn't do much.
And may be the reason is that I only read 9 volts at the plug's head...is that normal ?
Battery is ok : 12.40 volts

 

doesn't sound normal. well all i can think of is maybe the plug you tried is bad? try a different plug. see what happens.

 

the plug is brand new, faulty plugs is the first thing I was thinking of.
maybe a ground issue ? I'll carry on searching further.

I appreciate your help.

 

you are welcome and good luck. disclaimer: my experiences with diesels amounts to 2...neither a Volvo brand... a '84 W123 Mercedes 300D, and a '79 VW Rabbit, both of which were excellent
cars. The Mercedes did require a glow plug relay replacement at one point as I recall...which was readily available at the time online.

 

yes, I'm on my way to buy a new relay, but I'll test the old one first with an electric scheme.
the Volvo relay is available from auto brakes and there is an Hitachi substitute.

also - as you pointed out - one or more faulty plugs in the line could make the whole voltage fall (?)

I'll post the solution here in case it helps someone.

nice forum,
best regards