MD2020 starting problems - glow plug voltage

[SimonFa]

I've had problems starting Venezia since I got her and I've finally got round to trying to find out why.

I suspected the glow plugs weren't working and having checked found there isn't any voltage on the terminal connecting to them. There is an input voltage to the relay and I've swapped the relay with the starter relay and still no voltage. The user manual says there are some fuses on the output but I've had the unit off and can't find any. I'm a bit reluctant to poke about too much because it looks like a bit of a rats nest in there and I don't want to be pulling any wire off.

Anyone got any thoughts?

As always, thanks in advance,

Simon

 

[VicS]

Checking is made complicated by the fact that very early versions have an isolated negative while later ones do not.

Do you know which yours is or what version, A, B, C, or D your engine is

Even the glowplug indicator light is wired differently on the different versions ....

Essentially when the key is turned to the preheating position you should see 12volts on the orange wire from key switch ( terminal 19)................ if not suspect the key switch

and on the orange wire at the relay ( terminal 86)........... if not check the multipin connections on the wiring harness.

You should then have 12 volts on the red wire from relay to glowplugs ............... if not suspect the relay. But you have eliminated that possibility)

There should be permanent 12 volt supply while the battery isolator is ON on the red wire on pin 30 of the relay. This is probably what you have seen at the relay!



There is a fuse in the +ve supply to the control panel and in early versions in the negative connection too. If either fuse has blow the panel will be dead and nothing will work!


Refer to the wiring diagrams in the owners manual....... avaialble from http://www.volvopenta.com/volvopent...lication_search/Pages/publication_search.aspx if yours is not to hand, but be sure to refer to the correct version.

 

[SimonFa]

Checking is made complicated by the fact that very early versions have an isolated negative while later ones do not.

Do you know which yours is or what version, A, B, C, or D your engine is

Even the glowplug indicator light is wired differently on the different versions ....

Essentially when the key is turned to the preheating position you should see 12volts on the orange wire from key switch ( terminal 19)................ if not suspect the key switch

and on the orange wire at the relay ( terminal 86)........... if not check the multipin connections on the wiring harness.

You should then have 12 volts on the red wire from relay to glowplugs ............... if not suspect the relay. But you have eliminated that possibility)

There should be permanent 12 volt supply while the battery isolator is ON on the red wire on pin 30 of the relay. This is probably what you have seen at the relay!



There is a fuse in the +ve supply to the control panel and in early versions in the negative connection too. If either fuse has blow the panel will be dead and nothing will work!


Refer to the wiring diagrams in the owners manual....... avaialble from http://www.volvopenta.com/volvopent...lication_search/Pages/publication_search.aspx if yours is not to hand, but be sure to refer to the correct version.

Thanks Vic, I never thought about checking the key switch and chaing that thgrough.

As I said, nothing on the output of the relay and I've swapped it with the starter relay. They're not expensive so I'll get one anyway, another useful spare to have kicking about.

 

[SimonFa]

Essentially when the key is turned to the preheating position you should see 12volts on the orange wire from key switch ( terminal 19)................ if not suspect the key switch

and on the orange wire at the relay ( terminal 86)........

Turned out to be a dodgy mechanical connection on the ignition switch.

Thanks again.

Simon

 

[duncan99210]

You mention swapping the relays over (starter for plugs). I've found that over time the connectors the relays fit into work loose and fail to make a good connection, so swapping relays won't solve the problem. If you look into the box containing the relays, you'll see the connectors are simply female spade connectors. I used a thin emery board to clean them and a small screw driver to nip them up a bit so that you need to use a bit of effort to get the relay back in again. That solved the problem with the plugs a few years back.
More worrying this year was a failure of the starter: after a good deal of hunting round, checking switches and wiring, I thought to check the relay and found exactly the same problem with the starter relay connections as I had some years back with the plug relay. It's a five minute job to check and it will eliminate the relay connections as a cause if it doesn't solve the problem.