Can i upgrade my fog light relay?

landy-lee · Mar 3, 2022

Hi guys.

So after a crazy day of intermittent problem solving i have came to the conclusion that my wiper relay is faulty.

The unit is in the photo and they are now getting hard to get and on a long lead time form LR.

I believe it is a control unit that latches when the fog light button is pressed and then is connected to the main beam so when main beam is tuned off it will also turn off the rear fogs.

Can i some how replace the pektron unit with a upgrade kit of some sorts?

mystery · Mar 3, 2022

View attachment 260332 View attachment 260327 View attachment 260326change switch for latch type and swap switch head the down side is the rear fogs will stay on until switch off on the fog switch or lights or engine switched off

kermit_rr · Mar 3, 2022

Is it not a normal 'normally open' latching relay?

mystery · Mar 3, 2022

or change base to relay base to suit and use a latch relay using original switch https://www.arc-components.com/0-72...hing-changeover-relay-with-resistor-2147.html

kermit_rr · Mar 3, 2022

mystery said:
or change base to relay base and use a latch relay using original switch https://www.arc-components.com/0-72...hing-changeover-relay-with-resistor-2147.html

What is the purpose of the resistor?

mystery · Mar 3, 2022

A resistor across the coil provides a controlled path for the current when the switch opens. The resistor will convert the energy of the magnetic field to heat and allow the relay to switch faster than if it had a diode. Depending on the resistance, it will be almost as fast as if there was no protection. The downside is the resistor will always be wasting some power as long as it is on and there will still be some voltage transient. Depending on the resistor used, it will probably be 100+ volts, but not the 1,500+ of an unsuppressed relay.

Disco1BFG · Mar 3, 2022

mystery said:
or change base to relay base to suit and use a latch relay using original switch https://www.arc-components.com/0-72...hing-changeover-relay-with-resistor-2147.html

Will that relay not stay in the last position set when the power is removed ? I.E. if the fogs were on and you turned the lights off - then when you turn the lights back on, the fogs come back on too ?

mystery · Mar 4, 2022

as the switch on this model is the rocker type a latched type relay is not required and they will be active whilst the switch is in the on position with ignition and lighting switch on
hence the fog warning light but is this not the case with the present set-up
a latch relay would remain latched till the push type switch on later td5 models is pressed again to de-activate the latch to normal

kermit_rr · Mar 4, 2022

mystery said:
A resistor across the coil provides a controlled path for the current when the switch opens. The resistor will convert the energy of the magnetic field to heat and allow the relay to switch faster than if it had a diode. Depending on the resistance, it will be almost as fast as if there was no protection. The downside is the resistor will always be wasting some power as long as it is on and there will still be some voltage transient. Depending on the resistor used, it will probably be 100+ volts, but not the 1,500+ of an unsuppressed relay.

I won't pretend to understand any of that, not least 100+volts in a 12v lighting circuit

Disco1BFG · Mar 4, 2022

mystery said:
a latch relay would remain latched till the push type switch on later td5 models is pressed again to de-activate the latch to normal

Ok, Using a momentary SW to drive the relay, What would happen when the power is removed with the fog lights on ? ...

TIA.

mystery · Mar 5, 2022

Using a momentary switch and a latch relay(will not work with standard relay) the relay stays in the last state before power removed ,
so if fogs were on they would be on when you start the engine and switch lighting switch on unless you pressed fog switch again to disable fogs
you can get latched switches to suit the later td5 style where the font section of the switch with the legend or emblem are interchangeable
and the costs for this switch and a standard relay can cost the same or more than latch relayhttps://www.bearmach.com/product/dashboard-switches-elswswda/switch-assembly-air-compressor-motif-latch-type-suitable-for-defender-discovery-2-vehicles-and-universal-applications-ba-10311/BA%2010311?glCountry=UK&glCurrency=GBP&gclid=CjwKC

Disco1BFG · Mar 5, 2022

mystery said:
Using a momentary switch and a latch relay(will not work with standard relay) the relay stays in the last state before power removed ,
so if fogs were on they would be on when you start the engine and switch lighting switch on unless you pressed fog switch again to disable fogs
you can get latched switches to suit the later td5 style where the font section of the switch with the legend or emblem are interchangeable
and the costs for this switch and a standard relay can cost the same or more than latch relayhttps://www.bearmach.com/product/dashboard-switches-elswswda/switch-assembly-air-compressor-motif-latch-type-suitable-for-defender-discovery-2-vehicles-and-universal-applications-ba-10311/BA%2010311?glCountry=UK&glCurrency=GBP&gclid=CjwKC

Thanks - confirms my understanding

When I removed the MFU from my D1, I used a HRW timer relay for the fogs - which gives the correct functionality for the original momentary sw.... AND is an NVR, so fogs go off with the headlights and/or ignition, and stay off, until switched on again.....

Can i upgrade my fog light relay?

landy-lee

Well-Known Member

mystery

Well-Known Member

kermit_rr

Very

mystery

Well-Known Member

kermit_rr

Very

mystery

Well-Known Member

Disco1BFG

Well-Known Member

mystery

Well-Known Member

kermit_rr

Very

Disco1BFG

Well-Known Member

mystery

Well-Known Member

Disco1BFG

Well-Known Member

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