PDC control unit and rear view camera - Page 4

TerminatorX5 · #31 08-06-2012, 01:49 PM

did you tap to that wire and to the coil of the relay, or to the ground? if it went to the relay, what relay did you use?

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relentlessone · #32 08-06-2012, 03:21 PM

Quote:

Originally Posted by TerminatorX5

did you tap to that wire and to the coil of the relay, or to the ground? if it went to the relay, what relay did you use?

I tapped it to the coil, so when the PDC indicator light comes on, the constant 12v power connects to the power of the camera. I used a 12v 30 amp 4 pin relay I got at Pep Boys. I confirmed the relay works by trying it at another location, it just won't work off of pin #7 from the PDC.

I know you used the relay to ground the camera, but I didn't think it made a difference which method I used.

Any ideas?

TerminatorX5 · #33 08-06-2012, 03:36 PM

i am on the road, will get back as soon as i can

TerminatorX5 · #34 08-06-2012, 06:59 PM

I am not sure what the specs of your relay are, but you need something that will draw minimal amount of juice, as the LED green light that illuminates inside the PDC button on the front center console (module A169) draws just few milliamps, thus the output on the Pin 7 is a very low wattage, creating a super small amperage.

When you tap that wire, you dillute the flow of the current in two directions, one is to the original destination of the LED and the other one to coil of the relay. If the resistance of the coil is too low, it will draw a lot more juice, and essentially will shunt the other wire going to the LED, and as a result, will disrupt the operation of the PDC module.

The relay that I use, is a very small and is using just a fraction of the current that is coming on the Pin 7, and such, will not disrupt the PDC operation. If i had willpower and energy, I would have gotten the one that is Sensitive, and draws instead of 37 mA just 17 mA. Most automotive relays sold have rather higher level of triggering amperage. I have attached a datasheet for the one I was talking about.

The relay contacts applied groung to the special pin on the OE TV module (pin 17 on X18804), that supercedes anything going to the front monitor and displays image that is coming to two other pins on the same OE TV Module (X18806 TV Module, Pin 13 (+), pin 14 (-) from reverse camera). the relay did not apply power to camera, the camera was already powered from an ignition hot source in the trunk lid, it merely opened the gates for the signal to go to the monitor...

_________ LED in the front (A169)
l
l
(+ Pin 7)-------HrelayH------(-)ground
X300 coil chassis
PDC

The closing contacts of the relay go to (-) Pin 17 on X18804 (TV Module)
and to ground (chassis)

Do you have a factory TV module installed?

SlickGT1 · #35 08-06-2012, 09:10 PM

Term, where did you buy that relay? Thanks.

TerminatorX5 · #36 08-06-2012, 09:54 PM

can this link be opened?

12VDC/1A SPDT Micro Relay : Micro Relays | RadioShack.com

that is the exact one that i have, 37.5mA...

I should have been looking for the 17mA but I have been lazy... lol...

relentlessone · #37 08-06-2012, 10:39 PM

Terminator, thanks again for taking the time to explain. I am connecting the camera to a GPS unit that switches to video when it gets a video signal (when camera gets power), so I'm not using the TV tuner or anything like that.

I think I am just going to tap my relay into the reverse light wire and call it a day. I appreciate all of your help, I'm sure that many will get good use out of it.

TerminatorX5 · #38 08-06-2012, 11:25 PM

you are welcome. Even if you are not doing it this way, at least you know how it could be done using the OE parts...

The GPS unit that you are talking about - is it auto-sensing on the A/V input? does auto sense the type of video signal, PAL/SECAM or NTSC? If it is one of the chinese units that i saw on the ebay, it should be region-free and multisystem - i was considering it for the E39 that got traded in before that happened...

The reverse light is using Pulse Wave Modulation (PWM) and that means that the voltage on the light socket terminals is not steady 12VDC, but rather a wave, going from 12-14 VDC peak to maybe 6-8 VDC low, but in rapid succession, so the flickering of the lights is not visible to human eye. If a relay with a fast response time of the coil is connected to that source of power, and the power will go below and above the triggering point, the relay will flip the contacts and you may have the flickering issue, that has been disscussed already... to avoid that, either choose an alternative source of reverse activated power, or use a very slow responding relay, which will be too slow to react to the changes of the PWM and will hold the contacts engaged...

relentlessone · #39 08-06-2012, 11:58 PM

Quote:

Originally Posted by TerminatorX5

you are welcome. Even if you are not doing it this way, at least you know how it could be done using the OE parts...

The GPS unit that you are talking about - is it auto-sensing on the A/V input? does auto sense the type of video signal, PAL/SECAM or NTSC? If it is one of the chinese units that i saw on the ebay, it should be region-free and multisystem - i was considering it for the E39 that got traded in before that happened...

The reverse light is using Pulse Wave Modulation (PWM) and that means that the voltage on the light socket terminals is not steady 12VDC, but rather a wave, going from 12-14 VDC peak to maybe 6-8 VDC low, but in rapid succession, so the flickering of the lights is not visible to human eye. If a relay with a fast response time of the coil is connected to that source of power, and the power will go below and above the triggering point, the relay will flip the contacts and you may have the flickering issue, that has been disscussed already... to avoid that, either choose an alternative source of reverse activated power, or use a very slow responding relay, which will be too slow to react to the changes of the PWM and will hold the contacts engaged...

My GPS unit is a Magellan Roadmate 1700, and I believe it auto-senses the NTSC signal, but I have never tried PAL.

I was aware of the pulsing associated with the reverse lights, but not that I needed to worry about the response time of the relay. I'll hook my existing relay up and see if I need to get one with a slower response time.

I'll do some more research and see what my other options are for tripping the relay to power my camera. Thanks again.

SlickGT1 · #40 08-07-2012, 09:43 AM

I am also avoiding the whole TV setup. I though about getting the TV module, but decided to skip it.

I have the navtool. That intercepts the signal from the Navi DVD, and is supposed to show the camera. The relay is necessary to let it know when I hit reverse, or PDC as I plan to follow your setup. The one great thing, is that I can do a front camera as well with it.

All I have left to do, is get the cameras and that relay. I missed the radio shack link before. Almost there, and time to start wiring up.

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