Zorro587

Zorro587

Active Member
Hi All,

just a quick one for anyone who knows.....are there any differences between the coloured relays (yellow, green, etc) in the engine bay fuse box (and I'm guessing in other locations) and a bog-standard black-bodied relay, either 4-pole or 5-pole as required, that you get from a motor factors?
 
there are differences but I'll be buggered if I can remember what they are!
 
Green are five pin. Yellow are four pin. As long as you get standard relays of the same amperage they will be fine.
 
wammers said:
Green are five pin. Yellow are four pin. As long as you get standard relays of the same amperage they will be fine.
Click to expand...
Hmmm, I thought some of them had supression diodes fitted which standad relays do not have. If so, fitting a relay without supression will cause problems.
Will have to pull some lids off.
 
Datatek said:
Hmmm, I thought some of them had supression diodes fitted which standad relays do not have. If so, fitting a relay without supression will cause problems.
Will have to pull some lids off.
Click to expand...

Didn't know that Keith, if so yes maybe would be a problem. Supressed relays seem to be easily obtainable after a quick look around.
 
i replaced relay 7 (yellow) hevac blower with a standard automotive relay without any problems it had sufferd what i have now found out to be a common problem, burnt out. I am planning at some point to strip the fuse box and resolder it as mention on here in a previous post poss datateck i think.

as yet not got round to it still messing with out little niggly problems want to get my rear diff swopped out, leaking rear half shaft seal and air bags done for the winter just need a dry day to do it :rolleyes:
 
biketeacherdave said:
i replaced relay 7 (yellow) hevac blower with a standard automotive relay without any problems it had sufferd what i have now found out to be a common problem, burnt out. I am planning at some point to strip the fuse box and resolder it as mention on here in a previous post poss datateck i think.

as yet not got round to it still messing with out little niggly problems want to get my rear diff swopped out, leaking rear half shaft seal and air bags done for the winter just need a dry day to do it :rolleyes:
Click to expand...

Apparently on further investigation any relay that is switched by a semiconductor needs to be supressed. This prevents voltage surges destroying the switching device. However it seems that supressed relays don't last as long as normal unsupressed relays. Keith will know why this is so he is the electronics buff. Relay 7 appears switched by a semiconductor so i would fit a supressed relay ASAP.
 
Last edited:
wammers said:
Apparently on further investigation any relay that is switched by a semiconductor needs to be supressed. This prevents voltage surges destroying the switching device. However it seems that supressed relays don't last as long as normal unsupressed relays. Keith will know why this is so he is the electronics buff. Relay 7 appears switched by a semiconductor so i would fit a supressed relay ASAP.
Click to expand...
A supressed relay should last just as long as an unsupressed one as the supression usually only affects the coil not the contacts. Contacts may also be supressed, this would normally prolong the life of the contacts as it prevents any arcing on opening.
 
Datatek said:
A supressed relay should last just as long as an unsupressed one as the supression usually only affects the coil not the contacts. Contacts may also be supressed, this would normally prolong the life of the contacts as it prevents any arcing on opening.
Click to expand...

That is not what i read. It said that the contact release is slowed with supression and arching and welding of the contacts can take place with supressed relays shortening their life.
 
wammers said:
That is not what i read. It said that the contact release is slowed with supression and arching and welding of the contacts can take place with supressed relays shortening their life.
Click to expand...
Since the diode supresses the reverse voltage spike not the decay of the energising voltage.....................................................................
 
Datatek said:
Since the diode supresses the reverse voltage spike not the decay of the energising voltage.....................................................................
Click to expand...


Ok it seems the people that make them don't know what they are on about then.
 
Zorro587 said:
Time to throw some fuel on the fire then....having looked around I've found that there can be either a diode or a resistor fitted onto some relays.

Beal (Workshop Supplies & Consumables - Beal UK | Workshop Equipment | Garage Supplies) offer a 40A relay with a resistor across the coil that the accompanying blurb states is a LR replacement, not with a diode.

So I suppose the question now is.....resistor or diode?
Click to expand...

Don't know ask Keith he is the expert. Bumf i read said that relays suppressed by a rectifier diode that are used close to their max amperage suffer from arching and wear out quicker. Also that relays switched by a transistor need a diode to prevent voltage feedback from destroying the switch. But that diode could be in the switch circuit so the relay may not need one. They are not covered in oil so not my scene. :D:D
 
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