Relays - What's the operational difference between these?

[Chuffmeister]

As the title says, what is the operational difference between these two relays? I know they look different, but would they operate in the same way?

The Nagares relay is the one in my loom that powers the lambda heater circuit and fuel pump. I am assuming that the two 20a switches turn both circuits on when the ignition is engaged. I think my existing relay is sticking occasionally, so purchased a couple of spares. I found the same identical Nagares relay online, but was sent a generic one instead. I tried it this morning and it doesn't prime the fuel pump, so must be different?

http://www.polevolt.co.uk/acatalog/info_2794.html

The relay diagram looks similar, can somebody point out the difference?

[Vee8ight]

Look the same spec to me, unless the generic has been labelled wrong. Have you tried a third incase it's not the relay that's been sticking and you have another fault?

[phillpot]

Is the terminal orientation the same?

Edited by phillpot on Saturday 9th August 13:26

[Chuffmeister]

phillpot said:

Is the terminal orientation the same?

Edited by phillpot on Saturday 9th August 13:26

I thought that, but they are the same. Tried them again, my original works, but the new one doesn't. If I put a standard Bosch one in the fuel pump primes, however, this wont power the lambda heater circuit. Do you think it has something to do with the Nagares relay having double contacts from Pin30 as opposed to one on the generic relay (Ripca 279495)?

http://www.autospark.eu/shop/relays-12v/rdp5-12-na...


Nagares RDP 5/12


Ripca 279495

Edited by Chuffmeister on Saturday 9th August 14:23

[Sardonicus]

That is no good it clearly shows no diode in the circuit that's just a 5 pin generic relay

[Chuffmeister]

Sardonicus said:

That is no good it clearly shows no diode in the circuit that's just a 5 pin generic relay

Is the diode indicated by the line above the relay symbol/ under the switches on the Nagares relay? What other alternatives are there?

[blitzracing]

The diode is there to stop spikes affecting the ECU as the relay coil switches, it does not affect the physical switching of the relay as such, so you should still get 12 volts where you need it, but you could damage the ECU switching circuitry if the diode is missing. Wiring wise both those relay appear identical, Id be inclined to put 12 volts on the coil of the failing one and make sure you have 0 ohms between 30, 87, and 87b. If you take the lid of the relay, you will see the diode if it has one.

[phillpot]

Schematic for diode relay is the lower one.....

[MajorProblem]

Yes you need the diode to stop back emf from the coil when the feed is removed.

[Chuffmeister]

Thanks for your help and I am now a little concerned! But I still need a bit more help please!

So the original Nagales relay I removed shouldn't be there either? I have also just been back into the footwell to look at the other relay (in the black socket) and that has no diode either (see pic below)

So which relay do I need for the blue socket on the umbilical cord and which one for the black socket? I was told that you can swap the fuel pump and lambda relays over to test, but they are in fact different relays. I thought that the Bosch 0332 014 112 relay was for the black socket???

I could do with getting this sorted ASAP! Just need to know what relay goes in each socket please.

Edited by Chuffmeister on Saturday 9th August 21:30

[blitzracing]

Chuffmeister said:

Thanks for your help and I am now a little concerned! But I still need a bit more help please!

but they are in fact different relays. I thought that the Bosch 0332 014 112 relay was for the black socket???

I could do with getting this sorted ASAP! Just need to know what relay goes in each socket please.

Edited by Chuffmeister on Saturday 9th August 21:30

According to the wiring diagrams for the 14CUX, both relays are the same.... Also note the diode orientation is different, but Id not get concerned about this, either way it blocks then back EMF from reaching the ECU.

[davep]

The Bosch Red Stripe, or direct equivalent, is the relay you need for the Fuel Pump and Main Relay functions:

http://www.racetechdirect.co.uk/img/product/M0124_...

Note the diagram, it clearly shows a single pole single throw configuration and a 'series' flyback diode in the solenoid circuit.

[Chuffmeister]

Okay, thanks for the replies. It's amazing what you uncover when you do work on these cars. I already have one Bosch relay, so will order another to go with it and replace both currently in the car.

Cheers
Chuffy

[ianwayne]

I was in the footwell recently on my car. I can second the above, both my relays are the same Bosch part number.

[spend]

davep said:

Note the diagram, it clearly shows a single pole single throw configuration and a 'series' flyback diode in the solenoid circuit.

This IS the key element! Most common relays with diodes have the diode across (parallel) the solenoid. The bosch is only special in that the diode is in series with the solenoid. There is nothing special about the two pole arrangement (sometimes you need to isolate the circuits as they could also be 'switched' on elsewhere so you don't want them linked / sometimes you want dual contacts because of the load...)

ANY twin make & break (of the common format) should work, IMO inserting a diode into the cable going to the ecu would make them absolutely the same as the correct Bosch unit?