vito heater plug light?

[barryw]

Hi, can anyone help please?
I have a y reg merc vito which has become very difficult to start? I have noticed that the heater plug warning light doesnt always come on?
Many thanks Barry

 

[brandwooddixon]

Most likely uou have a glow plug which has failed.

A multimeter, resistive test will help you locate the faulty one.

Be careful when removing that you don't break it, by applying any sideways force.

 

[wireman]

It might be a wee but more complicated than just a plug dead,

A dead plug causes the light to stay on, not to fail to light.

The relay or the wires to it are my first guess.
The relay has a big fat cable from the battery which can fail at one of the two crimp lugs at its ends. The crimp terminals can get corroded and go high resistance cutting off the electricity supply just when its needed.

There is also a ground connection which could be the cause, this is only for the electronics in the relay so no heavy current is involved.

Connect a volt meter to the battery lug and the stud on the relay, turn the key to pre heat position and the voltage drop over the cable should be small <0.5volts, if its much more than this or several volts the cable is duff.

Depending on which relay you have there may be internal fuses on each plugs output pin failiure of these leads to the lamp stays on dud plug indication, and from your description it aint that wots wrong.

good luck and please let us know what cure you find.

 

[barryw]

Hi,
Hope to be able to get a look at the vito tomorrow, Thanks for your help, its nice to get this advice.
Will let you now how i get on, thanks again
barry

 

[barryw]

Hi, managed to get a look at vito tonight. Had a look at control relay and it sounds different to you described, with a couple of connections and one main large feed to plugs? I tested the feed to plugs and had a good voltage although a little confused by warning light? When i switch ignition on the warning light stays on for 2 seconds although the plugs stay on for 10 seconds even thought light goes out. I then get the plugs on again when vehichle starts for 10 seconds roughly? The light doesnt seem to conincide with what i had described in the earlier posts sorry. Many thanks barry