Any relay experts about.?

[Jixer]

Hi,
The neutral start relay on my JCB is kaput, JCB would be my last resort because of their huge markup.
I can’t find my relay in any comparison lists, can someone advise.?
It is a 4RD 003 520 25.

Thnx.

 

[JOEPRO]

I have alot of spare good used made in Germany mercedes relays. That just looks like a typical 4 pin relay. If so then I can send you one foc

 

[Barking Mat]

That's pretty standard, any good electrical parts store will have one.

 

[Brad93]

That's a standard relay

12v automotive relay should bring up similar. Just make sure the pin numbers are the same - that's standard convention.

Amperage needs to be suitable too. This is a bosch 30A equivalent

 

[Brad93]

Here's a genuine hella - new part has a 1 on the end.

https://www.autodoc.co.uk/hella/936605

 

[m_c]

The diode isn't that common in automotive relays, so it limits choices.
Depending on what is controlling the relay, the diode might only be there for noise suppression purposes. However if there's any electronics in that circuit, it'll likely be there for back emf protection (when a relay is switched off, you get a reverse voltage spike as the magnetic field collapses, which can easily fry the controlling electronics if they're not suitably protected).

Does it need to be a 5 pin relay?
The Hella one that Brad linked to appears to be out of stock everywhere, and I'm struggling to find any 5 pin with diode, and the same pin layout.
I fixed a JCB with this fault a few years ago (turned out to be the stalk), so can't remember what relay contacts are or aren't used.

You need to make sure the pin layout is correct.
There are two common pin layouts for this size of relay, so best to compare the original to any potential replacement.

 

[ajlelectronics]

Does it need to be a 5 pin relay?
The Hella one that Brad linked to appears to be out of stock everywhere, and I'm struggling to find any 5 pin with diode, and the same pin layout.
I fixed a JCB with this fault a few years ago (turned out to be the stalk), so can't remember what relay contacts are or aren't used.

A diode can easily be added to any relay.

 

[m_c]

A diode can easily be added to any relay.

They can, but they have a habit of failing, whereas built in ones generally outlive the relay.

 

[ajlelectronics]

They can, but they have a habit of failing, whereas built in ones generally outlive the relay.

Only if the wrong type of diode is fitted. Something like a 1N4007 will survive anything.

 

[Jixer]

I have alot of spare good used made in Germany mercedes relays. That just looks like a typical 4 pin relay. If so then I can send you one foc

Thanks for the offer, I can get one tomorrow locally hopefully.

 

[Jixer]

Here's a genuine hella - new part has a 1 on the end.

https://www.autodoc.co.uk/hella/936605

Thanks, I found that, but, wasn’t sure, I will try the local auto electricians first.

 

[MoreWellie]

I don't know but think this would work https://www.autodoc.co.uk/bosch/7309772