Infra Red Remote System (Yes, I searched!)

WordMan · Nov 23, 2018

I have searched and read a good dozen posts on the IR remotes, but I can't seem to find an answer to my particular problem.

1997 Sl320

Single button infrared remote

I have two remotes that work well, but only at night. In the daytime, even in the carport, no joy. I can get them to work if I hold the remote nearly against the sensor with my hand around the remote to block all light. All three sensor points work in the dark, but not with the sun up.

Thoughts?

RKH · Nov 23, 2018

Have you check the battery in the remote ? and clean the lens (of the remote and the receiver).

WordMan · Nov 23, 2018

RKH said:
Have you check the battery in the remote ? and clean the lens (of the remote and the receiver).

Both remotes have new batteries. I polished one of the receiver lenses, but it made no difference. The lenses on the remotes seem clear.

e-420 · Nov 23, 2018

in my case I had similar symptoms even with brand new remote batteries but ONLY with the trunk IR sensor. sensor was on it's way out and replacing the sensor solved the problem.

In your case, not working on all 3 sensors, wouldn't immediately have me believe sensors are the issue. and since it is with both remotes, doesn't sound like remotes. Not sure what that leaves for possibilities.

R129FE · Nov 23, 2018

I guess with the 97 the sensor is rather underneath the inner rearview mirror than in the doors or trunk, perhaps it needs some cleaning.

WordMan · Nov 23, 2018

R129FE said:
I guess with the 97 the sensor is rather underneath the inner rearview mirror than in the doors or trunk, perhaps it needs some cleaning.

Mine are in the doors and trunk lid.

WordMan · Nov 23, 2018

e-420 said:
in my case I had similar symptoms even with brand new remote batteries but ONLY with the trunk IR sensor. sensor was on it's way out and replacing the sensor solved the problem.

In your case, not working on all 3 sensors, wouldn't immediately have me believe sensors are the issue. and since it is with both remotes, doesn't sound like remotes. Not sure what that leaves for possibilities.

Well, you've answered one of my thoughts/questions, anyway. I was thinking perhaps the sensors were somehow daisy-chained and thus a single bad one might affect all the others.

The next question was, could all three sensors be bad. The car did spend a fair amount of its life in Florida (and the Florida sun), but I wouldn't think the sensors would degrade from sun exposure, rather I figured they would "go bad" (i.e. not work or work intermittently).

So the only common part is the brain, yes?

Which then leads me to the next question: as the brain appears to be discontinued, I'll need to buy one used (I see several on Ebay, so that's not a problem), do I need to match my part number exactly, or are they all interchangeable?

e-420 · Nov 23, 2018

R129FE said:
I guess with the 97 the sensor is rather underneath the inner rearview mirror than in the doors or trunk, perhaps it needs some cleaning.

97 doesn't have a mirror sensor, just sensors in each door and trunk.

WordMan · Nov 25, 2018

Well, since it's the thing that's common to all three sensors, I ordered a used module. We'll see if it works...

robm.UK · Nov 26, 2018

I had same problem with a '92 500SL. Read all the posts. Tried most things people recommended, including replacing fuses. No luck. I ended up solving the problem completely by accident while trying to sort out another problem.

Engine had an intermittent hesitation at high revs. Narrowed it down to MAS module. I did a blanket solder on the MAS module pcb, and... this is the relevant bit - at same time I unplugged every module in the engine bay and cleaned the contacts with electrical spray cleaner. While I was at it, I did same with the modules in the trunk. I also replaced the OVP.

[Edit - I also recall that I cleaned the earth straps to]

Hesitation was fixed, but to my surprise so too was the infra-red central locking. This was 2 years ago, and infra-red still works like new. Full daylight 5m away.

My best guess is that the problem with old infra-red locking systems is due to a build up of electrical resistance in the wiring/circuit over time, which could explain why cleaning the contacts and changing the OVP worked.

My best guess is that any change in the current to the IR sensors (by a few hundred milliamps) affects the sensitivity of the IR sensors to different wavelengths of light. The build up of resistance reduces the current in the IR circuit, which changes the sensivity of the IR sensors so that they no longer see the IR, or they have a reduced sensitivity to IR light.

Lee Wireless · Nov 28, 2018

WordMan said:
I have searched and read a good dozen posts on the IR remotes, but I can't seem to find an answer to my particular problem.

1997 Sl320

Single button infrared remote

I have two remotes that work well, but only at night. In the daytime, even in the carport, no joy. I can get them to work if I hold the remote nearly against the sensor with my hand around the remote to block all light. All three sensor points work in the dark, but not with the sun up.

Thoughts?

see attached

WordMan · Nov 28, 2018

Lee Wireless said:
see attached

I've read these, but they don't really help.

mrboca · Nov 28, 2018

Just get a small piece of black electrical tape and mount in where the door lens is, and then try.

I have an IR remote control for my PC and I just put a black tape in front of the receiver lens, and the remote functioned as it did without the tape. The tape acts as a "filter" for visible light, but the IR light goes through it (as long as it is not very thick).

If this helps out, I would say the lenses in front of the door/trunk IR receivers are not filtering the sunlight properly due to long periods of exposure to UV, and this interferes with the signal reception.

smata67 · Nov 28, 2018

I had the car for a while before I realized that the remote control needs to have its button pushed for about 2 seconds before it flashed the brighter red. In other words, this is not a momentary button that activates when press pressed and released. You must hold.

My remote works fine in the garage. Therefore, there is nothing wrong with the system in the car or the remote I am using. But I do get the same result of intermittent function when in sunlight. So sunlight is somehow interfering with the receiver (the car side). I guess the remote could also have weak output and this effect is worsened when it has to compete with sunlight.

Let's assume for now this is not the case and the receiver side is being affected by sunlight. So let's filter out as much non-IR light as we can on the receiver side. We can do this with an IR pass filter. Attached is a discussion of how to make one, exposed film and floppy disk material seem to have the property we are looking for. We can place this over the receiver lens and see if it now works. We can also remove the lens and just use the IR filter. Given that this lens is plastic, which we know is adversely affected by sunlight and it is exposed to the elements, a likely source of the problem is that this lens has degraded and is blocking IR that it should be passing. This test should reveal that.

http://www.lucidscience.com/pro-infrared light converter-1.aspx

Infra Red Remote System (Yes, I searched!)

WordMan

RKH

WordMan

e-420

R129FE

WordMan

WordMan

e-420

WordMan

robm.UK

Lee Wireless

Attachments

WordMan

mrboca

smata67

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