volvo d1 30 glow plugs staying on

[jackho]

hi folks , i posted this problem some time ago and have since replaced the glow plug relay and toggle switches. the glow plugs still remain energised so i disconnect the feed at the glow plugs every time i start the engine. i suspected the diode but checks out ok - but the negative side remains positive indicating a feed to the glow plugs. I suspect an open circuit at that side but cant figure where to look as the engine starts as normal on that 12v common feed.
Any suggestions welcome. Jackko

 

[VicS]

When you posted this before you seemed to be of the opinion that it was just the warning light, not the glow-plugs themselves which were staying on. but you now seemed to have confirmed that the glow-plugs do in fact remain energised. Is that correct.

I deduce from from what you say that you have a keyless control panel. Is that correct?

Are the attached wiring diagrams the correct ones for your installation


There were no responses to your previous post and none so far this time. Perhaps bumping this up and adding some wiring diagrams will get some useful replies

I'm stumped

 

[jackho]

When you posted this before you seemed to be of the opinion that it was just the warning light, not the glow-plugs themselves which were staying on. but you now seemed to have confirmed that the glow-plugs do in fact remain energised. Is that correct.

I deduce from from what you say that you have a keyless control panel. Is that correct?

Are the attached wiring diagrams the correct ones for your installation
View attachment 92286 View attachment 92287

There were no responses to your previous post and none so far this time. Perhaps bumping this up and adding some wiring diagrams will get some useful replies

I'm stumped

Again many thanks

 

[jackho]

Yes ... and thanks again for picking up on this . The normal start cycle functions "ok" ie feed through diode . with engine running the negative side becomes positive thereby maintaining feed to glow plug relay?? i am guessing there is an open circuit somewhere in the a common connection affecting the glow plug relay but possibly and uneducated guess at this stage.
windy and wet here today so cant get to boat but will take some more measurements including any ideas you might suggest.
( There is a loose yellow spade connection in around the alternator but i presume is a spare for additional sensor somewhere ) found when i was examining the connections around same while trouble shooting feed to diode.
Jackho

 

[jackho]

VicS .. looking at your drawings I see a Yellow going to S on the Alternator !!
Might be a red herring as I couldn't find a terminal (yet) - but while not knowing S function I could speculate its allowing a + back to glow plug relay !!??

 

[VicS]

VicS .. looking at your drawings I see a Yellow going to S on the Alternator !!
Might be a red herring as I couldn't find a terminal (yet) - but while not knowing S function I could speculate its allowing a + back to glow plug relay !!??

I was thinking about that. As far as I can find out "S" is a sensing terminal.
I think you should check the volts which the alternator is delivering to the battery,
You dont say if you have had this boat and engine from new if not maybe it's had a different alternator installed . If all seems to be Ok with the output and battery charging I' d insulate and secure the yellow wire out of harms way for now ... and also disconnect the other end from the main positive terminal on the starter motor solenoid

It might be something you will have to return to when the glow-plugs issue is sorted.


PS I just found the thraed you started on 23 May two years ago ... I missed that earlier .. answers some questions inparticlr about theengine version and the panel type

Thinking cap still on

 

[duncan99210]

The yellow wire is a battery voltage sensing wire for the originally fitted alternator. If a replacement alternator has been fitted then there‘s a good chance that it’s not set up for the battery sensing wire, so theres a good chance that it’s nothing to do with the conundrum posed by the OP.

 

[jackho]

Just a update folks , firstly I've had the boat from new. I have now connected the yellow wire to the alternator from where it had been missing for i dont know when.
didn't seem to make any difference to charging circuit . engine running battery's charging at 14,5 v.
Now the original fault - the glow plugs re energising after the engine start cycle. I have what I believe narrowed the problem down to the orange wire Terminal 6 terminating at connection 86 on the glow plug relay (thereby going positive momentary after engine starts and start button released.
(the negative end of the Diode positive on same supply - the diode testing good)
I now need any ideas where this orange T6 can get its supply from.
Somehow the alternator seems suspicious but my expertise end there - so any suggestions gladly accepted.

By way of further information I have spoken to Volvo technical in the past and they say this is a simple set up with Glow sw to relay. (both changed!!!)

 

[VicS]

The orange wire comes from the glow-plug / alarm acknowledge and test switch on the panel
It is normally energised when glow-plugs are energised by operating this switch

It is also energised via another orange wire and the diode in the panel when the starter button is pressed. This is to keep the glow-plugs on during cranking. (The diode prevents the glow plug switch back feeding power to the start relay during the preheating stage

There must be a short somewhere between the diode, the glow plug switch and the glow-plug relay from another energised wire to one of these orange wires.

Another possibility is that something is shorting onto the red/ green wire running from the glow-plug relay , via connection 7 on the harness to the alarm module ( red/ green is the connection to the glow plug indicator lamp in the module)

I would disconnect the red/ green from the relay to eliminate this as the culprit ( or otherwise). That will disable the warning light temporarily but that does not matter

I would check the wring on the glow plug switch ( its a new switch so we will assume the switch is OK)
Check the orange wiring from the diode to the glow-plug switch and from the glow-plug switch through the wiring harness to the relay
We will assume the relay is Ok as it is also new

Puzzled

I dont understand your thinking about an "open circuit" somewhere.

This might seem a silly question but how do you know the glow plugs are staying on ?

When you measured the volts on terminal 86, the cathode end of the diode, or the orange wire did you see the full battery volts or something less ?

 

[jackho]

( This is to keep the glow-plugs on during cranking. ) No . when glow switch toggle is released the supply to the glow plugs ceases. The engine is then cranked to start
provided gplugs held 10secs. - I had buzzer connected to GPs. - also get my fingers burned lifting wire off the gplugs.
When + at 86 Glow plug relay is active.
T6 goes back to the alternator so should this be positive and what is its function. My logic is that this becomes + when engine starts - so is this because of a circuit malfunction within the alternator??!!

 

[VicS]

( This is to keep the glow-plugs on during cranking. ) No . when glow switch toggle is released the supply to the glow plugs ceases. The engine is then cranked to start
provided gplugs held 10secs. - I had buzzer connected to GPs. - also get my fingers burned lifting wire off the gplugs.
When + at 86 Glow plug relay is active.
T6 goes back to the alternator so should this be positive and what is its function. My logic is that this becomes + when engine starts - so is this because of a circuit malfunction within the alternator??!!

Firstly
When you release the glow plug switch the relay is de-energised and the supply to the glow-plugs ceases BUT when you press the start button the relay should be re-energised via the diode and the supply to the glow-plugs restored during the cranking stage .... That's what the diode is there for.

OK your buzzer confirms that the glow-plugs really are energised after the engine has started.

Now
You say T6 goes back to the alternator ......... by T6, I assume you mean terminal 6 on the wiring harness connectors .... is that correct ?

T6 carries the wiring , the orange wire, from the glow- plug switch to the relay. There should be no connection to the alternator ... look at the diagrams I posted

If there is a connection between the orange wire/ T6/ terminal 86 and the alternator this probably explains what is going on although you don't say which terminal on the alternator it is connected to.
It would appear that due to this connection between T6 and the alternator the glow-plug relay is being energised directly from the alternator when the engine is running.

The obvious thing to do is to remove this connection and see what happens. But why is this connection there? How has this come about?

 

[jackho]

Thank you VicS ... yes you are correct on the start cycle. My error about glow plugs not active during cranking. Been distracted for a few days so will review when back at boat and post update in reply to your comments.

 

[jackho]

Happy to report my glow plugs are now back to normal. The problem in the end was finding the feed that was keeping the glow plugs live.
The 12v feed to alarm unit was shorted to the Glow plug feed. Short across pin 6 and 7 on multi connector at alarm panel. Corrosion between the pins - in the end I had to cut orange wire away from the connector and reconnect on the outside .
Obviously the load bearing pin is the most susceptible to cause an issue and hopefully will raise awareness to other users.
Thanks to all who assisted and especially VicS who's technical knowledge was appreciated.

 

[VicS]

Thanks for the feed back
Very glad you found the problem, clearly was not easy