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Premium Member
'92 300TE 4matic 280,000miles, '92 300TE 4Matic 'Ice Blue Metalic' 101,000miles
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Discussion Starter #1
Man, this car is punishing me for not using it more...lol. I've had this problem before;puddle lights come on when I open the front doors, but no overhead light.

There is no fix that I'm aware of other than to replace that IC chip which is probably the culprit. A JY overhead module light fixed this in the old TE....I jerked that out and put it in. And as luck would have it, the overhead light won't shut off after I shut the doors(yes, the switch was in the right position so that the light turns off on its own).

Going with the 'cold solder' theory(which I find only very rarely works), I re-soldered both units. No change.

Interesting that all the little plastic tabs that hold things held up except for the tabs that hold the sunroof switch in. Every single tab that holds that switch in, broke. It's ABS plastic....I can glue them back, but it's easier for now just put a tiny drop of Rhino glue in two corners and let that hold the switch in place.

The IC does have number sets all over it.....has anyone ever found that chip and replaced it? If I found that chip I could possible make three overhead modules work and could pass one along to the membership.

The cabin sensor was filthy with dirt and so was the one from my old TE.......I cleaned that one too, but not enough it seems.

Kevin
 

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Premium Member
'92 300TE 4matic 280,000miles, '92 300TE 4Matic 'Ice Blue Metalic' 101,000miles
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10,572 Posts
Discussion Starter #2
Rhino glue does not adhere well to ABS plastic. Put a tiny amount of ABS glue on the switch. Every thing back in....darkness when I open the doors. Madness because all the dome lights work if you switch to them.

Guess I'll go down the rabbit hole of replacing the IC chip in another unit.

Kevin
 

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W124 Moderator
86 190E 2.3L 16V, 2 95 320TE's, 02 S500
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12,930 Posts
Kevin

Given the dome lights work when you manually move the switch, do they stay on when the door is opened? I assume you've tested the door jam switch/switches, but I have to ask.

Jim

Sent from my SM-A515U using Tapatalk
 

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Premium Member
'92 300TE 4matic 280,000miles, '92 300TE 4Matic 'Ice Blue Metalic' 101,000miles
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10,572 Posts
Discussion Starter #4
Jim,
Of the two dome light assemblies, the one that has darkness when the doors are open has all the lights work manually. The other dome assembly....the one I pulled from the old TE, the dome light stays on after the doors are shut. But it too has all the lights work when you move the switch. That's the one I put in there and just moved the switch to no lights.

That's why I think it's the IC chip, because in both assemblies, you can manually make the lights work as they should with the switch.

Yes, I tested the door jam switches. Don't forget the puddle lights go on and off as they should as the doors open and close. That tells me it's that firggin' module chip.



Kevin
 

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Premium Member
2014 G550, 2000 SL500, 1995 E320 Cabriolet, 1980 TR8
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1,468 Posts
Yes, unfortunately, these seem to be a common failure item with age. I suspect that the IC is just a private label version of a standard automotive lighting controller, but even if you could find the cross reference, I'd bet that it is long since out of production.
 
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Premium Member
'92 300TE 4matic 280,000miles, '92 300TE 4Matic 'Ice Blue Metalic' 101,000miles
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10,572 Posts
Discussion Starter #6
Yes, unfortunately, these seem to be a common failure item with age. I suspect that the IC is just a private label version of a standard automotive lighting controller, but even if you could find the cross reference, I'd bet that it is long since out of production.
Bummer. But there may be some light at the end of the tunnel. In old analog audio gear, unobtainium IC's are coming out of Russia. They have literally restored old gear that had been idle for decades. Their failure rates are about normal and they're cheap.

I don't know how far I want to go down the rabbit hole, but this may be my only option.

Kevin
 

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Premium Member
2014 G550, 2000 SL500, 1995 E320 Cabriolet, 1980 TR8
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1,468 Posts
Bummer. But there may be some light at the end of the tunnel. In old analog audio gear, unobtainium IC's are coming out of Russia. They have literally restored old gear that had been idle for decades. Their failure rates are about normal and they're cheap.

I don't know how far I want to go down the rabbit hole, but this may be my only option.

Kevin
Totally agree! An an audiophile myself, I'm glad some of this stuff is coming back from the dead. You can now get reliable KT88 and 12AX7A vacuum tubes and even Nixie tubes if you fancy them (I do - the only issue is that the Russian tubes use an upside-down 2 as a 5 whereas the original Burroughs had a dedicated 5).
 
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Premium Member
'92 300TE 4matic 280,000miles, '92 300TE 4Matic 'Ice Blue Metalic' 101,000miles
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10,572 Posts
Discussion Starter #8
Totally agree! An an audiophile myself, I'm glad some of this stuff is coming back from the dead. You can now get reliable KT88 and 12AX7A vacuum tubes and even Nixie tubes if you fancy them (I do - the only issue is that the Russian tubes use an upside-down 2 as a 5 whereas the original Burroughs had a dedicated 5).
Yeah, who would have thought the Russians would play a part in old analog restoration this late in the game??!

Supposedly their IC's are sold through vendors on eBay.....crazy.

Kevin
 

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W124, 230E 5 speeds Manual
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The dome light can be easily bench tested for proper operation. you can simulate closed and open doors and test its functions. if you are willing to do the test just ask here and I will provide the wiring diagram and help you with the testing. all you need is a 12v source and some wires.

Be aware that there is a Relay that controls the dome light hidden behind the instrument cluster. it is the same relay that has the ignition buzzer.
2654196
 

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2014 G550, 2000 SL500, 1995 E320 Cabriolet, 1980 TR8
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The "relay" in the ignition buzzer module is actually just a diode so there are no moving contacts to wear out. If this module is disconnected, the dome light will not trigger via the driver's door, but the passenger door should still trigger it.
 

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'92 300TE 4matic 280,000miles, '92 300TE 4Matic 'Ice Blue Metalic' 101,000miles
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Discussion Starter #11
The dome light can be easily bench tested for proper operation. you can simulate closed and open doors and test its functions. if you are willing to do the test just ask here and I will provide the wiring diagram and help you with the testing. all you need is a 12v source and some wires.

Be aware that there is a Relay that controls the dome light hidden behind the instrument cluster. it is the same relay that has the ignition buzzer.
View attachment 2654196

You bet....at this point I'm game for anything!

I have a nice Fluke and jumper wires....lead me to it...lol. I can troubleshoot one of the two extras I have.

Kevin
 

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About a dozen 1988, 1989, 1990, and 1991 sedans, wagons, 4Matics and 1 coupe
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I've had the dome light failure in several of my 124s and always solved the problem with a JY part. The problem these days is that there aren't any 124s in the junkyard. When i think of all the 124s sans jacking tube/rocket panel rot in the southwest getting crushed it hurts. Really hurts.
 

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Premium Member
'92 300TE 4matic 280,000miles, '92 300TE 4Matic 'Ice Blue Metalic' 101,000miles
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10,572 Posts
Discussion Starter #13
I've had the dome light failure in several of my 124s and always solved the problem with a JY part. The problem these days is that there aren't any 124s in the junkyard. When i think of all the 124s sans jacking tube/rocket panel rot in the southwest getting crushed it hurts. Really hurts.
Hear that. I'm tired of JY dome light modules and yes, this is a common problem on the 124's. That and the convience module under the carpet that starts to get funky about controlling your windows and sunroof from the door lock.

I don't think we can afford to just throw them away anymore. Like the cruise control modules, I'm sure they can be fixed.

Most of the 4Matics that had languished in JY's for so long are crushed by now. That really hurts.

Kevin
 

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Ok. I forgot to say that Things will be a lot easier if you have a spare plug somehow that you can attach to your domelight for easier connection with the pins.
As per the attached diagram, we re goin to focus on the top right Reading/dome lamp. The pins in question are 1, 2, 3 and 4
From your 12v power source: connect pin 3 to positive and pin 4 to negative.
Now pin 1 can be connected or not it just tell the light that the ignition is on so it change the timer behaviour when opening and closing the doors.
Right now you can test the manual function of light with the switch it shall turns on.
Now you need to simulate door open scenario via pin 2 . You do this by grounding pin 2 and the light shall turn on. Disconnect pin2 from the ground and wait a little the light shall turn off. This is the normal function.

Thr pin numbers are written on the plug obviously so you can identify them.
 

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Premium Member
'92 300TE 4matic 280,000miles, '92 300TE 4Matic 'Ice Blue Metalic' 101,000miles
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10,572 Posts
Discussion Starter #15
Ok. I forgot to say that Things will be a lot easier if you have a spare plug somehow that you can attach to your domelight for easier connection with the pins.
As per the attached diagram, we re goin to focus on the top right Reading/dome lamp. The pins in question are 1, 2, 3 and 4
From your 12v power source: connect pin 3 to positive and pin 4 to negative.
Now pin 1 can be connected or not it just tell the light that the ignition is on so it change the timer behaviour when opening and closing the doors.
Right now you can test the manual function of light with the switch it shall turns on.
Now you need to simulate door open scenario via pin 2 . You do this by grounding pin 2 and the light shall turn on. Disconnect pin2 from the ground and wait a little the light shall turn off. This is the normal function.

Thr pin numbers are written on the plug obviously so you can identify them.

Ok, you say, "Now pin 1 can be connected or not it just tell the light that the ignition is on so it change the timer behaviour when opening and closing the doors."

Connected to 'what'?

I can cut the plug from my donor car so I have leads. Give me a bit to try all this.

Kevin
 

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Ok, you say, "Now pin 1 can be connected or not it just tell the light that the ignition is on so it change the timer behaviour when opening and closing the doors."

Connected to 'what'?

I can cut the plug from my donor car so I have leads. Give me a bit to try all this.

Kevin
Connected to positive.
 

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Premium Member
'92 300TE 4matic 280,000miles, '92 300TE 4Matic 'Ice Blue Metalic' 101,000miles
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10,572 Posts
Discussion Starter #17 (Edited)
Ok. I forgot to say that Things will be a lot easier if you have a spare plug somehow that you can attach to your domelight for easier connection with the pins.
As per the attached diagram, we re goin to focus on the top right Reading/dome lamp. The pins in question are 1, 2, 3 and 4
From your 12v power source: connect pin 3 to positive and pin 4 to negative.
Now pin 1 can be connected or not it just tell the light that the ignition is on so it change the timer behaviour when opening and closing the doors.
Right now you can test the manual function of light with the switch it shall turns on.
Now you need to simulate door open scenario via pin 2 . You do this by grounding pin 2 and the light shall turn on. Disconnect pin2 from the ground and wait a little the light shall turn off. This is the normal function.

Thr pin numbers are written on the plug obviously so you can identify them.

OK...so I got into this tonight.

I took my original overhead module from the old TE for the test. It was replaced because the seat-belt light wouldn't turn off and/or blinked incessantly. And.....the interior overhead lights wouldn't come on when set to the 'auto' feature.....but the lights all worked individually.

So when I put power to #3 and grounded #4 like you said, no lights came on with the switch on the 'auto' feature. Then I grounded #2 and both lights turned on. Disconnected #2 like you said and in a few moments the lights both went out and then the seat belt light went out.

If this is normal, I may sub in this unit as it appears to be working. Unless you want me to do more tests?

Kevin
 

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Registered
W124, 230E 5 speeds Manual
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84 Posts
Ok. I forgot to say that Things will be a lot easier if you have a spare plug somehow that you can attach to your domelight for easier connection with the pins.
As per the attached diagram, we re goin to focus on the top right Reading/dome lamp. The pins in question are 1, 2, 3 and 4
From your 12v power source: connect pin 3 to positive and pin 4 to negative.
Now pin 1 can be connected or not it just tell the light that the ignition is on so it change the timer behaviour when opening and closing the doors.
Right now you can test the manual function of light with the switch it shall turns on.
Now you need to simulate door open scenario via pin 2 . You do this by grounding pin 2 and the light shall turn on. Disconnect pin2 from the ground and wait a little the light shall turn off. This is the normal function.

Thr pin numbers are written on the plug obviously so you can identify them.

OK...so I got into this tonight.

I took my original overhead module from the old TE for the test. It was replaced because the seat-belt light wouldn't turn off and/or blinked incessantly. And.....the interior overhead lights wouldn't come on when set to the 'auto' feature.....but the lights all worked individually.

So when I put power to #3 and grounded #4 like you said, no lights came on with the switch on the 'auto' feature. Then I grounded #2 and both lights turned on. Disconnected #2 like you said and in a few moments the lights both went out and then the seat belt light went out.

If this is normal, I may sub in this unit as it appears to be working. Unless you want me to do more tests?

Kevin
Your unit is working as it should.
But don't be very sure, once in a time, I had the same problem but only after installing the unit into place. if I tap on it or I remove it it would work normally. It was a cracked solder joint that was breaking the circuit when the unit is slightly bent when in place. so try to tap on it or bend it slightly and see if something changes in order to be sure it is fine. But as you said I guess your t is probably good.

Now that you know how it works. take your multimeter and go test the plug in your car. you know which wire should have ground when you open the door. all you need is to check that ground continuity and so...
 

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Premium Member
'92 300TE 4matic 280,000miles, '92 300TE 4Matic 'Ice Blue Metalic' 101,000miles
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10,572 Posts
Discussion Starter #19
Thanks so far for the testing procedure! I did reinstall it and it works fine.

But it's been my experience, specially in these cars, that they don't 'fix themselves'. And this was a known bad unit from my other car.

Now the one I took out(which I re-soldered) does not fare well with with your test. The dome light comes on when I hook up #3 and ground #4. When I ground out #2, the dome light blinks like the seat belt light. Maybe I accidentally bridged a solder connection or this means the IC chip is bad?

I have another unit I'll test too.....I would like to have a working spare because I have no confidence in the unit I put in over the weekend.

Kevin
 

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I had the same issue with one of my domelight where the light start blinking with the seat belt light. I did resolder it but never installes it into the car. I m pretty sure you havent bridged any connection. It s likely a bad IC
 
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