Those silver relays with a red diagonal line

[lazyitus]

You know, those two relays near the ECU ?

Silver 5 pin 12v 30A Bosch things.

Went to replace these two yesterday and bought a couple of relays from Halfords which seemed to be correct with regards to voltage and ampage etc.

But they made the car not work. Instead of getting the normal fuel pump buzz, I got an excruciating buzz from one of the new relays.

So, I put the old one back into the offending socket and it was OK again.

My question is:

Should I stick specifically with metal Bosch ones? Did I make an error putting a Halfords black plastic one in, even though it appeared to match the numbers etc...

?

[blueg33]

The Bosch relays are protected by a diode so that voltage and current spikes will not kill your ecu.

You need the diode type ones, you can get other makes not only Bosch, but I play safe and buy Bosch ones usually from ebay

[lazyitus]

Thanks Blue !

[BIGMIKE1]

I got mine from euro car parts, the brand new ones are now brown plastic. I ended up with one metal and one plastic as thats what they had in stock.

[blitzracing]

I had a Bosch one to bits at the weekend, and as Blue says there is a "flywheel" diode in there that stops the spikes getting back to the ECU when the relay is switched off. Apart from that there was no other electronics of any sort. Ill do a check for coil resistance and the physical pin layout compared to a standard relay and see what the crack is. I dont understand why it would buzz, I dont think lack of a diode would be responsible for this.

[lazyitus]

Cheers Mike. I work round the corner from Euro Carparts so I'll try in there.

Cheers for the info Blitz.

[lazyitus]

Well Europarts don't have any.

So checked ebay.

£20 !!! EACH

[blueg33]

lazyitus said:

Well Europarts don't have any.

So checked ebay.

£20 !!! EACH

I am sure Maplin have them as do some online car electrics suppliers, but they will be the plastic version.

With ebay you have to be patient

£10.30 on Britishcarparts.co.uk


edited - Maplin don't have them now

Edited by blueg33 on Tuesday 15th November 17:25

[lazyitus]

blueg33 said:

With ebay you have to be patient

I bloody will be patient at £20 a throw !

[EGB]

Clev Trev supplied me 12months ago. About £11

[BIGMIKE1]

lazyitus said:

Well Europarts don't have any.

So checked ebay.

£20 !!! EACH

They will be able to order them in from another branch, all you should need to do is give them the part number, my invoice shows 450220610. I paid £7.20 incl vat, but think that was with staff discount as a mate worked there till last month

[Loubaruch]

The Bosch part number is:

0332 014 112

I paid about £9 each last year from my local TVR dealer: Hexham Horseless Carriages

[lotusandy]

I have had one from here in the past, worked fine

http://www.vehicle-wiring-products.eu/VWP-onlinest...

Part number R30BT RELAY 30A 5-B TWIN MAKE/BREAK £5.75

I have used this company for many years, always good quality stuff & quick delivery..
But note the one I linked will work ok under all normal circumstances, however the genuine Bosch relay has a diode in series with the coil to prevent damage to the ECU if the battery is connected the wrong way round!

[lazyitus]

Ah thanks chaps. I can stomach those costs a little easier. Wouldn't mind so much if I hadn't just spent £11 for 2 in Halfords in error! Should have checked here first.

[lazyitus]

EGB said:

Clev Trev supplied me 12months ago. About £11

Got a couple from these people. Thanks alot.

[evox]

Just a bit more info, the Bosch relays use both output pins on the relay as one, they are linked together inside the relay and do not act as a change over and therefore this might explain some of the problems that have occured. So unless you are prepared to modify the loom keep to the Bosch relays

I hope that makes sense.

[lazyitus]

evox said:

Just a bit more info, the Bosch relays use both output pins on the relay as one, they are linked together inside the relay and do not act as a change over and therefore this might explain some of the problems that have occured. So unless you are prepared to modify the loom keep to the Bosch relays

I hope that makes sense.

Yes, it does. Thanks.

[blitzracing]

evox said:

Just a bit more info, the Bosch relays use both output pins on the relay as one, they are linked together inside the relay and do not act as a change over and therefore this might explain some of the problems that have occured. So unless you are prepared to modify the loom keep to the Bosch relays

I hope that makes sense.

So you are saying that it has a 5 pin configuation, but two of the pins get switched on or off at the same time?

[spend]

Just a twin make/break with diode across the coil, nothing more nothing less....

[evox]

Blitz,

Yes that is correct.

Spend,

Not quite the relay has the diode connected from the power supply in series to the the coil not across the coil.