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Finding the lamp socket should be pretty straightforward. I think it is the red socket, but going from memory, so please check it out. Simply pop out the socket and have someone put the car in reverse.
I'm also thinking the red and brown wires are the 2 you need to focus on, but, again, please confirm by testing.
Mark, just to be clear, I only have the one (red) wire shown in my pic (#15) which is supposed to provide the switching when connected to the reversing light? Not sure how I am to connect:
C. Wire from chassis ground should go to camera negative power input lead.
D. Connect positive camera lead to relay contact 5 (normally open contact) which becomes energized with 12V positive when car is in reverse.
Mark,
in my previous post (post number 15 above) I attached a picture which showed (near the relay) the single red wire supplied with my device to be attached to the reversing light. I am unsure how I am to connect the ground wire to the negative side of the camera cable and the postive wire from the load side of the relay to the positve side of the camera cable, when all I have is this one red wire? I have no access to the (4 pin) sealed cable which goes from my device to the camera?
Hello Mark,
Apologies, it's me again!
Please see below; do I have this right, please? 1 top left in pic, 2 behind it and joined to 3 with 5 on its own to the right?
If this is correct, would 5 go to the red camera wire AND the ground, please?
Hello MEC (I don't know why I suddenly decided to call you Mark)!
Please could you number the pins on the relay, either a drawing or using the pic in post number 15; I am unable to decipher which pin is number 3? The diagram on the side of the relay appears counter-intuitive to me? It shows 1 & 2 above what is actually 3 pins and it shows number 3 above what (I take to be) pin number 5?
Sorry MEC,
The numbers next to the terminals are so small that with my poor eyesight, I couldn't see them! I have only just noticed them!!
I was trying to rely on the diagram, which confused me?
Hello MEC,
Thank you for asking.
Had to suspend the operation a while...Away on business, but I am confident that on my return I shall succeed given your instructions and now that I have realised that each terminal has a tiny number next to it!
It seems obvious once you know, but unfortunately (I really must get round to new glasses), I only saw the numbers for the first time when looking at a blown up photo of the relay!
Stupidly, I had been trying to wire it up using the diagram on its side!
I will let you know as soon as I have it cracked...
Hello MEC,
The white bulb holder in my previous pic is the reversing lamp. It has two red wires, both going to the contact at the side of the bulb with constant 12 volts. It has a white wire going to the base of the bulb, again with constant 12 volts, which should convert to ground when reverse gear is selected.
I have spliced into the two reds and connected them individually to terminals 2 & 3, so that I now have 12 volts at both of those terminals.
I have spliced into the white (switching) wire and connected it to terminal 1.
My ground wire and the camera wire are on terminal 5.
Unfortunately, when I select reverse gear, my screen does not switch to reversing camera and the relay continuously switches on and off so quickly it sounds like a monstrous mosquito! It literally vibrates in my hand, so I quickly pull the ground wire to avoid burning it out?
Switched my multimeter to volts (black probe to ground) and while in reverse checked white wire terminal 1, it read 0.154 volts (not 12 volts, but not zero)? Switched to Ohms, white wire terminal 1 reads 3.50 milli-Ohms, not zero?
MEC, I think my relay has different terminals to your diagram? Anyway, just in case this is so and is helpful, herewith a (hopefully) clearer pic:
Please use only one of the constant 12V wires for the relay. It has to be the wire that goes to the backup lamp. Please don't use both of the red wires.
To test for correct 12V positive and negative wires, insure that you get a 12V reading at both wires (polarity is very important) coming from the backup lamp. Start with testing one red wire using the positive test lead and black test lead to the grounding lug of the car. If you get a negative 12V reading, the polarity is reversed.
I did not have 3 lamp wires connected to the relay. Two lamp wires only.
Apologies for my electrical ignorance. There are two red wires going to the same terminal in the bulb holder (the terminal that touches the ‘body’ of the bulb) and both of them are positive 12 volts. My splice into each of them gives me 12 volts positive at both terminals 2 & 3; I am unable to understand why using just one of them (say, for terminal 2) and then further splicing that splice for terminal 3 would make any difference?
I very obviously could be wrong?
Just to assist my understanding of these things, one of the red wires comes from the main loom and the other from the Brake Light Bulb Holder? Could it be that both the brake and reversing lamps are 12 volt positive wired in series and both are then actuated by grounds? If so, does this mean that the red from the loom carries 12 volts TO the reversing lamp and the other red takes it FROM the reversing lamp to the brake light? Is this what you mean by polarity, please?
In any event, I shall do exactly as you say and second-splice the existing splice coming from the MAIN LOOM red wire (to terminal 2), connecting it to terminal 3.
Okay, I disconnected from the red wire linking the reverse lamp to the brake light and connected just the single red (from the loom to the reverse lamp) to both terminals 2 and 3.
Unfortunately, as soon as I connect the ground and camera wire to terminal 5, the relay buzzes like a bee!
When in reverse and checking for volts at the white wire on terminal #1 I get 0.095 volts and for Ohms I get 0.64 k Ohms; shouldn't both of these be zero, or is this irrelevant, please?
Could it be that the ground is not needed here, given that the white wire on terminal 1 is converted into a ground when reverse is selected?
What do you think, please?
Please recheck my instructions and schematic. You'll note that the chassis ground is only to be connected to the camera ground. This may even be at the front of the car. No chassis ground should go to the relay. I believe your white lamp wire will serve as your relay 12V negative (ground) when the backup lamp is on.
My earlier posts regarding the chassis ground mistated that you would use that for mirror and relay, but the schematic and instructions are corrected and have the chassis ground going only to the mirror harness where 12V ground (-) is required.
If you'd like to have a conversation, we can set a time for a call. Private message me if you'd lkle to do this. I think it will help to get you moving forward at this point.
Hello MEC,
Thank you for such a prompt reply!
There is no camera ground. the cable plugged into the screen goes directly to a short 'tail' on the camera; this tail is obviously so a small hole can be drilled from outside for the tail and the connection made inside the boot roof liner. The cable has 4 male contacts which plug into 4 female contacts within the end of the camera tail. The rear camera is powered and works fine as a rear camera.
The cable also has (coming from it) a thin red wire which is to be wired into the reversing light and this is supposed to cause the screen to switch to the rear camera when reverse gear is selected. The problem here is Jaguar's use of a ground to initiate the reverse lamp.
I have wired everything to your previous instructions, but now I am going to try removing the ground wire and plugging the red wire directly into terminal 5 on its own?
If that doesn't work, then I will take up your kind offer to call.
I really did make a meal out of this! I thank you for your patience in seeing me through to the end; I find automotive electronics to be a ‘Dark Art”?
I did not need the ground wire. I plugged my thin red camera wire into terminal 5 and hey presto! So to recap, (as you stipulated) the red constant 12 volt wire from the loom (not from the brake light) is connected to both terminals 2 & 3 on the relay. The white (switching) wire is connected to terminal 1. The camera wire to 5.
I cannot post pictures because when I (very carefully) first spliced into one of the red wires it literally came away from the bulb holder in my hand! Then, the shortness of the red wire from the Brake Light to the reverse light meant I had to cut the bulb holder out altogether to remove the terminal and re-solder a wire onto it. I had no white wire, so used yellow and my red is more orange; consequently, a picture of the final result would cause more confusion than enlightenment!!
But at least it works, so again…Thank you and thank you for my early Christmas present!
You should also get a 12V test lamp or multimeter to find which wires going to your backup lamp are 12V positive when the lamp is in both the on and off condition. You can do this by checking the leads into the lamp socket when the backup lights are on. Please keep in mind that there will be 2 - 12V positive leads when the backup lamps are off (yes, this is not a typo). One of the leads changes to negative when the backup lamp is on. You should identify that lead as well to insure you get both negative and positive wires identified when the backup lamp is on.
Those 2 leads will be used to power the relay. The lead that changes to 12V negative when the backup lamp is on will be the ground wire for the coil side of the relay. The lead that is 12V positive all the time will be the 12V positive for both the coil side of the relay and the supply side of the relay. The ground wire that you run will be for the camera. The 12V load (positive) side of the relay will go to the camera as well.
To recap; the 12V switching lead (changes from positive to negative when the backup lamp is on) is connected to the ground contact of the coil side of the relay. The 12V positive lead that is always on gets connected to both the positive side of the relay coil and to the positive side of the relay supply.
The positive wire from the load side of the relay goes to the positive side of the camera cable. The wire from the grounding lug goes to the negative side of the camera cable.
Hope that all helps. I'll keep on eye open for any follow-up posts.
I was reading your great posting above and wondered how many mA this puts on the battery when the car is turned off? I tried running power from my navigation system and the pos/neg wire for the trigger on a standard relay. The reverse camera comes on when it is suppose to, but I noticed that my battery gets drained overnight with a draw of more than 40 mA. If I disconnect the pos/neg backup light wire from the relay the mA draw drops down to the normal level.
Thanks,
11-28-2023, 06:35 AM
Finding the lamp
