300d 4 ME

Hi, I have a slight dilemma... I just installed a new set of the pencil-type style glow plugs(upgrade) on this Benz. I have tested them all, they work fine. I wired these in parallel. When I turn on the switch to pre-heat I hear a relay/buzzer- click on under the dash. The gp-light doesn't light up. When I crank it, the light flickers on/off. I check with a multi-meter all the fuses, plugs. It seems that when I crank it,Im seeing about 7volts at the glow plugs, nothing before or after. To make sure that the new plugs were good, I hooked up a temp. + feed off the battery, they work perfect. I have always thought that the relay was flaky in the past. It is about 30' F. degrees at the moment, does the temp sensor have something to do with this. Or has the relay finely crossed the creek? Is the relay under the dash, or out side at the fender, or fire wall? There are alot of boxes that look the same. In these pics, what are the junctions on the left fender, and firewall for?, they have relay's under neath.

Thanks!

240D 3.0T

Those are not for the glowplugs.

Outre

I do not remember if it is your year or 1979; some of the Relays used are not compatible with the mod where you only replace the Glow Plugs and make Jumper Wires for them.

You Glow Plug Relay may be behind the Instrument Cluster.

300d 4 ME

Allright, then its the clicking relay behind the dash. It looks like I have some further testing to do......

300d 4 ME

I know its been a little while but, I fixed the plugs.

I hooked up a 1985 Ford Truck solenoid, on the fender. It works great. The hardest part was to find a place for the switch(a toggle switch). I cheated,.. I guess you can see in the pictures. It sat right in the air vent nicely. Who knew a lamp switch would be so handy...

Thanks for all of the help!

Outre

I did the same on my Volvo some years ago. I got the Solenoid at a Junk Yard for $5.
On mine the 2 large Red Wires are from the (+) Battery Terminal and the single large Red Wire goes to the Glow Plugs.
Where the 2 (+) Red wires bolt up is a Green Wire that has (+) Voltage going to the Switch and the other Green Wire comes from the Switch to the S Terminal on the Solenoid.
The Solenoid is grounded through the Solenoid Bracket screwed into the Fender Well.
Since the Solenoid is rated for the amperage of a Starter it ought to out last the Car.

Outre

Thanks for getting back a telling us how you solved your problem.

Also nice Photos.