Back Up Camera Issue

[chas3]

There is an older thread, including diagrams/photos/explanations to install failures.

[jaynana]

if i may resurrect this thread, i have the same problem (although the symptom is different). i think the noise on the signal light is caused by the 'hot check' of the light.

i have done the below tests:
Scenario 1. engine not running, key in position 2, put gear gear into reverse-> relay engages, camera works perfectly.

Scenario 2. engine running (key in position 2), put gear into reverse-> relay starts making a continuous pulsating 'TRRRRRR' noise! audibly it must be like 10htz or so.. the camera still works because the frequency is enough to flip the video module to show the camera feed. but occasionally the screen flickers (so i don't have lines going across the display etc).

the bulbs have a hot check and a cold check. so i assumed this to be the hot check that is coming out as noise.

in fact i did a further test: while in Scenario 2 above, i touched a direct +12v onto the reverse light pin (87) on the relay (through a 5A fuse just in case). and sure enough the relay stops pulsating and sure enough, a 'Check Reverse Lights' comes up when the key is later turned off. this is why i assumed it must be the hot check causing the noise.


in any case adding the second relay wouldn't stop the relay pulsating at the frequency of the light check. it possibly fixes the problem by synchronizing the NTSC timing of the camera by giving the same pulse onto the other wire of the camera?

what i'd like to do is to create scenario 1 ie hold the relay down without making it go TRRRRR.. isn't there a way to do this, options in my mind:

1. switch off the hot check of reverse lights (but how?)
2. a 2000uf (too high?) or so capacitor across pins 85 and 87 (relay would stop pulsating but that might impact the light check).
3. a 2000uf or so capacitor across pins 30 and 87? (relay would still pulsate but the video module would get a constant feed.. hopefully).

[TerminatorX5]

your relay is fed off the reverse lights? the Cold monitoring happens periodically when the light is off, the hot monitoring is happening periodically when the light is on... it is not a continuous signal, there are series of short bursts hitting the bulb, in most cases not long enough to overcome the induction of the relay and to activate the relay... waht you are probably experiencing is a PMW - Pulse Modulating Wave, a signal coming from the LCM that modulates the intensity of the light output by modulating the 12 VDC - a constant series of 0V with 12V (nominal, actual values are 0.5 VDC to 14VDC) with gaps of 0 Volts DC and 12 VDC spaced so the light output is either dimmer or brighter, depending which level of voltage is held longer...

10 Hz pulsating is rather high, which makes me think, that there might be another issue at stake - the lights are powered by the LCM, which powers the lights via transistors, and may so be, that the additional load of an automotive relay that is being used is too much for the sustained current on the transistor's collector, and it is cutting in and out, thus creating the "pulsating" effect... if that is the case, you may eventually fry the transitor inside the LCM, which will render the module defective... applying a direct +12 VDC to the light bulb while it is connected to the LCM may burn the back end of the transistor that powers the light bulb, again, rendering the LCM defective - you should be careful, as the LCM also stores the mileage information of your car...

you may wish to consider replacing the automotive relay with the one with a smaller current draw (see this post http://www.xoutpost.com/918829-post36.html for the spec on the relay that I would recommend)

[jaynana]

thanks,

i have tried disabling the light checks which didn't solve the problem. your analogy explains why, i guess its the said PMW that is noticed as noise. not the light checks.

thanks also for indicating the risks of what i've done. fortunately i don't think there's any damage so far.

i can change the relay to the likes of what you have shown (i have searched around and found suitable models), but that still doesn't solve the problem does it?

the PMW would still be felt by the relay as noise?

[TerminatorX5]

do you have factory PDC?

[jaynana]

yep both front and rear. why?

EDIT - think i know what you're thinking- drive the relay from the PDC on signal?

wonderful! would you know which 'box' in there is the pdc controller and which wire i can tap onto, to drive the relay pls?

[TerminatorX5]

you may consider tying camera to pdc operation - when pdc activated automatically or manually via button, camera comes on. i have it on mine and love the pdc button activating camera. i have a write up in pdf, if you want to see it. give me your email address, i will send pdf

[jaynana]

Hi, that sounds fantastic!

i've sent you an email (email option in the forum) with my email. please send me the pdf

cheers

jay

[TerminatorX5]

email sent

[jaynana]

thanks! i'm at work wanted to do a quick scan but coudln't resist the tempatation

so its pin 7 on the middle black plug X300 that i'm after - which is the signal that connects to the LED on the PDC switch right? (I already have Ground from somewhere else instead of pin 6 you have mentioned i hope that is ok..)

everything else is already wired in my case. my camera is also permanently powered when the car is 'awake' like you have (can't remember what i tapped onto though..)

before getting my hands dirty i will also get myself a micro relay as well and replace mine.

cheers mate

j