eugeneb2015
Rover Rookie
Posts: 12 
Location: New Zealand
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Post by eugeneb2015 on Sept 25, 2015 8:28:08 GMT
Hi
I am fitting a pair of halogen headlamps to my P5B and I'd like to fit a relay to protect the switch. I have read quite a few posts and while people mention fitting a 20A HD relay behind the console no one seems to mention what to wire to the relay.
So I assume you take the wire off terminal 4 of the switch that goes to the head light switch (30). Then connect one side of the relay coil to terminal 4 and the other to Gnd.
The wire from the headlight switch then goes to the NO contact on the relay and then you take a 12V feed from terminal 2 or terminal 8 to the common of the relay?
Finally can you get replacement switches as I may as well change it while I have the console out..
Also I have replaced my fog lights as one had blown, with some new units I found on Ebay - GE 4412A. after installing I found that they keep blowing fuses, are there any common things to look for - a post mentions the dip switch may be at fault?
Cheers
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Post by petervdvelde on Sept 26, 2015 8:02:53 GMT
i installed some relays near the fusebox and didn't need to alter anything behind the dashboard. The LH and RH head lights each have their own fuses. I switched these together (which is on lots of cars) and used the fuse which became free for the steering circuit. Because of the positions of the relays, i didn't need a lot of changes to the standard wiring. An + feed and - for the relay's is were needed. It is difficult to explain  Regards Peter |
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Post by djm16 on Sept 26, 2015 11:46:15 GMT
You will need a pair of relays, one for dipped the other for main beam. Place them as close as possible to the headlights. Run a 20A cable direct from the battery supply to the starter solenoid (fused).
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tonys
Rover Fanatic
Posts: 428
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Post by tonys on Sept 26, 2015 18:57:43 GMT
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Post by lagain on Sept 26, 2015 21:13:09 GMT
Excuse my asking, but why do you need a relay ?
I have Halogen lights on my car with standard bulbs and assumed that they would draw about the same as the original lights.
I have had no problems with them and last night they were on for a couple of hours going from Glasgow to Carlisle and no burning smells !
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Post by petervdvelde on Sept 26, 2015 21:32:11 GMT
The contacts in the switches are rather small and every time you switch on your lights, a small spark wears out the switch contacts and after some time the contact surface creates a resistance which can burn out the switches. The Halogen lights have a higher amperage then the standard lights so could boost the process described above. A relay has a much lower current for the switches then the lights. So then you wear out the relays which is cheaper and easier to replace.
Peter
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Post by johnwp5bcoupe on Sept 27, 2015 9:22:50 GMT
Excuse my asking, but why do you need a relay ? I have Halogen lights on my car with standard bulbs and assumed that they would draw about the same as the original lights. I have had no problems with them and last night they were on for a couple of hours going from Glasgow to Carlisle and no burning smells ! Quite correct George if the Wattage is the same they draw exactly the same current as the original bulbs, I dont know why people worry so much about original items now drawing too much through the wiring  most of it has plenty of resilience and is more than adequate!! |
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Post by lagain on Sept 28, 2015 19:26:19 GMT
Thanks for that, John,
when I first had my car I thought it would be very cool to connect the fog lamps to the main beam on the headlights, so I just took a wire from the dip switch, through an accessory switch (so that I could turn them off for the MOT) and on to the fog lights.
In the 70s there was far less traffic on the roads so main beam was on for much longer than today and if I flashed any one they got all 4 !
There were never any ill effects and it was only after many years when I started to understand electrics that I stopped doing it !
Rover must have used much thicker wire than they needed to.
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Post by djm16 on Sept 29, 2015 2:59:57 GMT
Try putting a voltmeter across the terminals of the switched on halogen bulb (engine off) you will be lucky to read more than 11V even though your battery is still reading 12.5V. It even be as low as 10.5V. This means:
a) 10-20% of your 2x60W is being dissipated / wasted as heat and not brightening up your day / night.
b) 10-20% of your 2x60W is heating up and damaging the several switches / junctions between your battery and your light bulb.
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eugeneb2015
Rover Rookie
Posts: 12
Location: New Zealand
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Post by eugeneb2015 on Sept 29, 2015 9:27:23 GMT
Hi
Looks like I've started something here!
From what I have heard and read on a few forums etc the Sidelight park 3 position switch is prone to failure. Some of this can be put down to the age/usage of the switch contacts over its lifetime due to current drawn by the Head and fog lights ( all are fed through the switch). So as a precaution people started install relay(s) to stop the switch from burning out. I have seen posts on this forum from people who have had smoke coming out of the instrument cluster. A relay is a a way to limit the current through the switch, pretty much all modern cars have relays stop limit the current going through the switches.
I have had a look at the wiring diagrams and I like Peter's solution as its easy to do and can be removed for originality later if so required...
Cheers
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dave3066
Rover Rookie
Posts: 26
Location: Scottish Borders
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Post by dave3066 on Sept 29, 2015 12:29:30 GMT
Hi Looks like I've started something here! From what I have heard and read on a few forums etc the Sidelight park 3 position switch is prone to failure. Some of this can be put down to the age/usage of the switch contacts over its lifetime due to current drawn by the Head and fog lights ( all are fed through the switch). So as a precaution people started install relay(s) to stop the switch from burning out. I have seen posts on this forum from people who have had smoke coming out of the instrument cluster. A relay is a a way to limit the current through the switch, pretty much all modern cars have relays stop limit the current going through the switches. I have had a look at the wiring diagrams and I like Peter's solution as its easy to do and can be removed for originality later if so required... Cheers I fitted a single relay to the headlamps on my 1966 P6 just for that very reason. I've had both the sidelight (twice) and the headlamp switch fail whilst driving at night and the reason for failure was heat. These switches get very hot when the lights are on for any length of time. So hot that you can't touch the switch contacts without burning your fingers. The hot and cold cycling causes the contacts to fatigue and eventually fail. Since fitting a relay I've not had a single failure in 2 years of daily driving. So the relay takes the load off the switch contacts. It's nothing to do with the output of the lamps themselves. Dave |
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Deleted
Deleted Member
Posts: 0
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Post by Deleted on Sept 29, 2015 13:46:08 GMT
I have original sealed beamed units and very very rarely drive my car in the dark. At most I use sidelights if the conditions warrant it.
But I did use the car a lot at night at one time driving from London to Plymouth. At no time was there any problem with switches getting hot or smoke billowing from the pod.
Only a guess, but I would imagine that Rover made sure the gauge of the wiring was adequate.
IMO, not wishing to upset anyone.
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Post by lagain on Sept 29, 2015 20:52:05 GMT
All I can say is that, touch wood, all my switches are the originals.
I am wondering if the switches heat up due to poor earthing. At a recent pub meet several members had problems with lights not coming on properly. One of the problems with using the body to earth.
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Post by petervdvelde on Sept 29, 2015 21:04:05 GMT
Resurgam,
It is not the wires which generally causes problems (the P5 has thick wires indeed). The connectors and the contacts in the switches is were problems can occur. Fitting relays is a matter of precaution. It is possible that someone doesn't have problems when relays are not fitted but when the problem occurs, there is no way back and you could face a lot of damage with burned out switches and/or wiring and you could face a period of unreliable electrics. It is often stated that Lucas is the Prince of darkness but i believe that the Lucas components are not always the cause. It is often the fault of the car manufacturer who didn't fit relays to save some costs. In every car or motorbike i restored, i fitted relays to the headlights, fans and horns and never had a electrical problem. In lots of (German) classic cars and motorbikes, relays were fitted but in English classic cars, these are not always fitted and that may be the reason that English classic cars (and Lucas) have a bad reputation on electrics.
Its everybody's own choice to fit or not fit relays but it is a fact that all modern cars have lots of relays, especially on components like the lights which draw a lot of current.
Peter
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Post by petervdvelde on Sept 29, 2015 21:13:26 GMT
All I can say is that, touch wood, all my switches are the originals. I am wondering if the switches heat up due to poor earthing. At a recent pub meet several members had problems with lights not coming on properly. One of the problems with using the body to earth. Iagain, Its not an earth problem which causes the switches to heat up. Heating up only occurs when there is a resistance and this resistance can be there due to corrosion, dirt or burned in contacts in the switches. Poor earth will give more dimmed lights because there is an additional resistance in the circuit but it will not burn the switches. The body is in general a good earth system but corrosion can occur where the wires are connected to the body or on the connector which is in contact with the body. Peter |
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Post by enigmas on Oct 4, 2015 9:32:43 GMT
I agree with all your comments Peter. Poor earths/grounds are a major issue with many classic car electrical faults. To add to this though, all modern vehicles use relays to direct heavy current to the source requiring it...starters, headlights, driving lights, winches, etc. The dash switch simply activates the relay which does the heavy current switching. The starter solenoid in your car is actually a heavy duty relay.
Most mass produced cars prior to the 1970s rarely used relays to switch circuits for headlights, as they usually would only power 35/55 watt lights (or something similar) Most Chryslers, Fords and Rovers of the period 'cook' the headlight switch if quartz halogen headlights of say 55/100 watt beams are used. (How do I know this?) The switch (contacts) run hot and eventually burn...I've put out an under dash fire in a Ford. I ran high output halogens on my P5 coupe for years (fantastic night lights) prior to fitting relays on all circuits. The switch would get hot to the touch. To conclude, properly wired relays safe guard circuits and switches, and also ensure that full current is fed to whatever device requires it.
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Post by Phil Nottingham on Oct 4, 2015 16:12:14 GMT
60w main and 45w dip - 12.8 is optimum min voltage
OE for a P5B was actually 75/45 60/45 is P5 and the standard of the time on numerous cars
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Post by lagain on Oct 5, 2017 20:01:22 GMT
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Post by petervdvelde on Oct 5, 2017 20:19:46 GMT
Interesting as the light output on my Rover is less compared to my wife's Peugeot. Please post your feedback once installed
Peter
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Post by djm16 on Oct 6, 2017 15:14:12 GMT
I believe the H4 LEDs you are fitting are the ones I have on both P4 and P5. While they are very bright and fit together with their driver inside the headlamp bowl, they needed some adaption. Specifically, the dipped beam pattern is too drastically turned up to the near side and needed an additional shields glued to the LED housing.
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Post by lagain on Oct 7, 2017 21:00:30 GMT
Interesting as the light output on my Rover is less compared to my wife's Peugeot. Please post your feedback once installed Peter I have now done all the sidelamp bulbs, including the brake lights and the headlamps. The result is just amazing. The front side lights are more like running lights and the rear lights are brighter with a wider spread, it looks very crisp. The headlamps I have used are Wipac RTC 4615, which are period but take a H 4 bulb. |
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Post by lagain on Oct 7, 2017 21:11:36 GMT
I believe the H4 LEDs you are fitting are the ones I have on both P4 and P5. While they are very bright and fit together with their driver inside the headlamp bowl, they needed some adaption. Specifically, the dipped beam pattern is too drastically turned up to the near side and needed an additional shields glued to the LED housing. Have been playing with them this evening with my Wipac RTC 4615 lights. They do not kick up to the left any more than the H4 bulbs did. The bulb can be turned in the housing to get it correct. The light is better than the H4 bulbs but not what you would get from a modern set up. The trouble is that any H4 headlamp was originally designed for a Land Rover Defender. Having said that it has transformed the night time driving experience, possibly because of the whiteness of the light that can counter all the white bright lights coming the other way. Also the switch no longer gets hot, so money well spent. |
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Post by djm16 on Oct 9, 2017 10:00:34 GMT
Interesting!
The prism on my headlamp glasses puts up the near side by about 10 degrees. The LED by another 10 (before masking the LED).
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Post by lagain on Oct 10, 2017 20:42:06 GMT
Interesting! The prism on my headlamp glasses puts up the near side by about 10 degrees. The LED by another 10 (before masking the LED). Does it do the same with halogen bulbs ? My Wipac shells have a hood over the top of the bulb, but the beam is perfect horizontally and the kick up OK. They obviously have had problems as the bulb can be rotated, but the instructions said to start with the adjustment on '3 o'clock', which I did and that was fine |
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Post by Roy of the Rovers on Oct 11, 2017 12:24:01 GMT
[/quote]I have now done all the sidelamp bulbs, including the brake lights and the headlamps. The result is just amazing. The front side lights are more like running lights and the rear lights are brighter with a wider spread, it looks very crisp. The headlamps I have used are Wipac RTC 4615, which are period but take a H 4 bulb.[/quote] Welcome to the world of LEDs George  Night driving is a hundred times better isn't it... well worth it.(and fully reversible) |
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most of it has plenty of resilience and is more than adequate!! 
