Hi all, I've been a long time lurker but now I am in need of some help. I am working on a mechanism from a Porsche vintage car. Im on my phone so apologies in advance if this isn't clear. The mechanism has 3 inputs and a series of 5 relays. Red is constant 12v, brown is earth and yellow is 12v switched on car. I can get the mechanism to work correctly by applying 12v to brown and earthing red till it runs and hits the limit switch, then earth to both red and yellow it runs in the opposite direction till it hits the limit switch. This is the correct operation of the mechanism BUT it won't work in the car as brown is earth on the car and red is 12v constant and yellow is 12v switched. Am I being a complete fool here?
Any help would be appreciated. I have no idea why there are 5 relays as I would have thought 2 would suffice.
Thanks is advance.

 

Welcome to AAC.

Unfortunately, your explanation is far from clear. This doesn't seem like a difficult problem but without a clearer explanation it will be difficult to help.

Let's try to clarify things.

1) Is this the mechanism?

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2. If the wiring diagram above isn't what you are working on, what is the year and model of the car?

 

Apologies for not being clear. The system utilises a 944 sunroof mechanism, the early model one mentioned here
https://www.clarks-garage.com/shop-manual/body-03.htm

 

Hi. I hate to be the idiot who makes this suggestion, but I've seen it before where people diagnose a problem without ever checking the fuses. Have you checked the fuses?
A friend of mine replaced the timing belt on his car because he thought that was the problem. The real problem was that he was out of gas.

 

Hi. I hate to be the idiot who makes this suggestion, but I've seen it before where people diagnose a problem without ever checking the fuses. Have you checked the fuses?
A friend of mine replaced the timing belt on his car because he thought that was the problem. The real problem was that he was out of gas.

Hi there, yes, I have 12v constant to red on car and switched 12v on yellow when I turn on the headlight switch

 

What is confusing me, is that the mechanism will work perfectly when 12v constant to brown(brown is earth on car wiring)

 

A friend of mine replaced the timing belt on his car because he thought that was the problem. The real problem was that he was out of gas.

Same guy, same car - headlights would not come on unless you stepped on the clutch. That one had him hugely baffled. They'd work but only after you've stepped on the clutch. Finally he gave up and said I could have the car. One night no matter what I did I couldn't get the lights to come on. Opening the hood I saw a light coming from one of the ground connections. Not realizing what it was I was looking at I touched it with my finger. Got an immediate burn. Bad ground! Turned out there were a lot of bad grounds. Since I owned the car now - I made all new ground points to the chassis from the battery and from the engine block. That was the last of that problem.

Stay tuned for more car adventures with this Chevy Geo.

 

Would it be right in saying that this is a h bridge setup??

 

Would it be right in saying that this is a h bridge setup??

Can't be sure. Wife had an 89 Celica with pop-up headlights. It's possible. But it was a long time ago when we scrapped that car. She loved it until she wrecked it.

 

View attachment 359064
Based on what I'm seeing - the motor runs only in one direction. What stops it at a given position is the rotary switch and the relay above the motor. Guessing but it looks like power is applied to the rotary switch either of the two tall wires and the rotary switch. In the shown position - if power is applied to the right most wire (not the wire going to the relay contact) the relay should turn on and the motor should run until the rotary switch with the outer gap reaches the contact lead. When it reaches the open position the relay drops out and shorts the motor, both poles, to ground effectively stopping the motor from over-running its "stop" position.

 

Full open
View attachment 359066
Line B activated; Rotating clockwise to close
View attachment 359067
Rotating
View attachment 359068
Rotating
View attachment 359069
Rotating
View attachment 359070
Line B disconnects from relay; Fully closed.
Or vice versa, which ever may be the case.

Motor drives one way - from Open to Closed or from Closed to Open.
Activate line A to do the opposite. From closed to open.
Next time you switch the headlights from on to off or vice versa, the rotary contact will continue to rotate clockwise.

 

HEh! You might have a bad rotary switch. If - as you possibly elude to - you reverse power to the motor it may run in reverse. But looking at the schem. I see the motor can only run one way. Like the arms of a windshield wiper, the motor runs one way while an arm raises the lamps. Run the motor further and the arms bring the lamps back down.

Don't know what you're calling a limit switch - but if it's that rotary switch I've drawn in five different positions then it's not really a limit switch it just shuts the motor off at a given point in its rotation. The fact that the relay shorts both motor leads to ground to stop the motor from continuing to coast to a stop suggests they want the motor to stop hard at that location. So I'm keying in on your rotary switch. It may not be seeing much abuse, but up and down and up and down can take a toll on a rotary contact. Vintage Porsche - what year? Likely worn out.

OK, I'm done. 't's all I can do.

 

Here's a direct question with comments:

Looking at your diagram: 12VDC from battery (Red - or "R" for short) passes through the lamp control switches. That puts power on (in my diagram) line A, your diagram the Red,Green (RG) wire. When the key is on SW2 provides power to the headlights (not important to this issue) and power to the Grey (Gy) wire. With the cam in the position shown the relay will activate and apply power to the motor. The motor raises the headlights. On SW2 there's a Black,Yellow wire (BY) that is powered only when the key is on. Apparently it looks like there might be an indicator light Grey,Blue (Gy,B) (see note 2).

When switched to Parking Lights (only) the headlights do not light or raise. But the side markers and license plate lights come on.
When you turn the key off the RG wire conducts power to the relay moving the motor until the cam reaches the shown position. The key is off - the headlights have shut off and have retracted.

With the key on and the lamp switch set to headlights ON the Gy wire turns the relay on and the motor moves until the cam has rotated 180˚ and the headlights are in the up and ON position. If you have the headlamp assembly on the bench for testing then power the grey wire and the lights should rise up. Turn the Gy wire off and turn the RG on and the lamps should retract.

If the headlight extends and retracts as described then the problem is in the lamp control switch. Likely the Gy wire is not getting power to the cam. The cam is what decides what position the headlights are to be in.

The questions are: Is this what you're finding when bench testing? Or are you testing on the vehicle (far more easily tested there)? And when you test and as you say it functions normally, have you checked for voltage on either the Gy wire or the RG wire?

I can get the mechanism to work correctly by applying 12v to brown and earthing red till it runs and hits the limit switch, then earth to both red and yellow it runs in the opposite direction till it hits the limit switch.

Earthing (grounding) the red and powering the brown would run the system backwards. Stop doing that. You might damage the cam and cam switches. If you haven't already done so.
Another question: What happens when you power the red RB wire and ground the Brown (Bn) wire?

 

Apologies for not being clear. The system utilises a 944 sunroof mechanism, the early model one mentioned here
https://www.clarks-garage.com/shop-manual/body-03.htm

If we're talking about the headlight system why did you link us to the sunroof?
The diagram, as I have just realized, is not your posting. Ya’akov generally has some pretty good and reliable information. Still, the diagram is his post, not yours. Do you have a diagram of your own showing what you have?

{I hate chasing weasels when I'm looking for rabbits}