No low beam
10-24-2017, 10:33 AM
#1
Instructor
Thread Starter
No low beam
My 1984s refuses to dim its lights. It had a 928 618 107 02 relay. I removed it and jumpered between 30a and 56a then 56b. The high and low beams on both sides worked. I ordered a new relay. I cleaned the grounds and checked the 4 headlight fuses. I got a new 928 618 107 05 Friday. I replaced the relay. No change. I removed the dimmer switch and replaced it with the switch from my parts car. No change. I sprayed all the connections with deoxit. I sprayed the old relay inside and out with deoxit. I removed the CE panel and made sure there was no rodent damage and all the connectors were in the sockets. With either relay and any of three switches in place the headlights come up when they are turned on, the brights come on but the dimmer has no effect on the high/low beams. The blue high beam indicator stays on whenever the lights are on. I need some guidance on how to test the switches and the relays. I am aware that there has been a problem with the 928 618 107 05 relays in the past. I am guessing that is my problem but I would like to test both relays and all three dimmer switches before sending the new relay back and getting another one. Any help would be very much appreciated.
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10-24-2017, 05:26 PM
#2
Captain Obvious
Super User
Super User
Is the high beam side of the relay getting the trigger +12 regardless what you do with the steering column stalk switch? If it does, trace the line back and see where it gets energized. If not then the problem are the two replays (old and new).
11-02-2017, 12:29 PM
#4
Instructor
Thread Starter
After some searching I found an explanation of the headlight wiring that I could follow. The repair is still a work in progress but I thought I would post the following 2010 explanation for future use in 1984 and older cars.
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Thread Starter
Join Date: Aug 2010
Location: Netherlands
Posts: 17
Default Porsche 928S2 (1984) Combination Light Relay
Hello Shark Lovers,
Last year, it happend once with my 1984 S2, that I turned the lights On and nothing happend. The lights didn't pop up and didn't turn On. I cranked them up mannually and they turned On. I drove away and the lights worked fine, when I switched them Off they went out and down. So I turned them On again they worked as advertised. A bad contact maybe?? I finally forgot all about it.
Yesterday night however, I turned the lights ON and they went On, but didn't pop up. What the heck??? Some Heavenly lights on a shark? Then slowly they popped up, first half way and then fully. I drove home and turned them Off and On, and again and again they worked as advertised.
I searched all English and German 928 forums, and read about all sorts of problems with the lighting system, but nobody ever explained how the Combination Light Relay / Motor switch works (to complicated). So I tried to figure it out myself (How I love those crumpy 928 schematics). It took me all night, I still don't know what the heck is/was wrong with my lights, but beneath is how I think the system should work. If anyone has any additions / suggestions please let me know, also if somebody figured out the inside (electronic logic) of the relay, please show me. I don't want to break open my relay if it is working (most of the time?).
Porsche 928S (1984) Combination Light Relay (CLR) XIX-XX
This CLR has three functions:
1) Operate the Concealed Headlight Motor to go Up and Down.
2) Operate the Headlights ON and Off.
3) Operate the High/Low beam function of the Headlights.
To do this the unit has three relays and some simple electronic cirquitry to perform logic functions when operating the 3 relays. The motor relay also has some sort of spark protection (capacitor?).
The CLR has 12 contacts:
1) 30bM Supplies 12V to the Motor Switch (30b) to turn the lamps down.
2) 30b Receives 12V from the Light Switch only in position 0 (All lights OFF)
3) X Receives 12V from the Ignition Switch postion X (12V in position I and II)
4) 56 Receives 12V from the Light Switch only in position II (main lights ON)
5) 30a Receives 12V from the Battery true 16A fuse 19 (Concealed Headlight Motor)
6) 30 Receives 12V from the Battery unfused to power the head lights
7) 31 Ground connection for electronics and relays inside the unit
8) 86M Receives 12V from the Motor Switch (86) to turn the motor relay ON
9) 30M Supplies 12V to the Motor (30) to make it turn.
10) 86 Receives 12V from the Steering Colum Switch (56a) when Hi beam is selected
11) 56a Supplies 12V to the Hi Beam Lights over 8A fuses 24 (Left) and 25 (Right)
12) 56b Supplies 12V to the Lo Beam Lights over 8A fuses 27 (Left) and 28 (Right)
The Concealed Headlight Motor (30) receives 12V from the CLR (30M) and is connected to ground (31). There is a Motor Switch on the Concealed Headlight Motor, this position switch has three contacts:
1) 30b Receives 12V from CLR to turn the lamps DOWN.
2) 86 Supplies 12V to the CLR (86M) to turn the motor relay ON.
3) 56 Receives 12V from Light Switch (postion II) to turn the lamps UP.
In switch position UP contact 86 is diconnected from contact 56 (30b is still connected).
In switch position DOWN contact 86 is diconnected from contact 30b (56 is still connected).
In all switch positions between UP and DOWN all three contact are connected, therefore one diode is used on 30b to prevent contact 56 from powering it and one diode is used on 56 to prevent contact 30b from powering it. Both diodes only carry the relay drive current (+/- 100 mA not the motor current).
If the 56 diode would break (open cirquit), the lights will not come up. If the 30b diode would break (open cirquit), the lights will not go down. If the 56 diode would short cirquit, the lights will probable come down when commanded but could maybe come back up again immediatly afterwards. If the 30b diode would short cirquit, the lights will probable come up when commanded but could maybe come back down again immediatly afterwards.
Basic operation is as follows:
Main Lights ON:
1) When the Light Switch is turned into position II (Main Lights ON), the Motor Switch receives 12V (56). When the lights are not Up, the switch (86) then supplies this 12V to the CLR (86M) to turn the motor relay ON.
When the CLR (X) also receives 12V from the Ignition Switch postion X, the internal logic will:
2) Turn the motor relay on (30M) and supply 12V to the Motor (30) which will start turning untill the Lights are UP and the Motor Switch 86 disconnects from 56.
3) Turn the light relay on and supply 12V to the Hi/Lo relay, which will turn ON the Lo Beam (56b) or the Hi beam (56a), when it receives 12V from the Steering Colum Switch (56a).
If the Ignition Switch does not supply 12V to the CLR (X) the motor relay is not powered and nothing happens.
Park Lights ON:
When the Light Switch is turned from position 0 into position I (Park Lights ON), the Motor Switch will not receive 12V (56). When the lights are not Up, the switch (86) will Not supply 12V to the CLR (86M), the motor relay will not turn ON and the lights stay Down.
When the Light Switch is turned from position II into position I (Park Lights ON), the CLR will turn the light relay Off and the lights turn Off. The Motor Switch will no longer receive 12V (56), but it does not yet receive 12V (30b), so the Motor will not turn and the lights stay Up.
Lights OFF:
When the lights are Up, the Motor Switch (30b) will receive 12V from the CLR (30bM), the motor relay will turn ON and the CLR (30M) supplies 12V to the Motor (30) which will start turning untill the Motor Switch (30b) disconnects the CLR (86) when the lights are Down.
If the Ignition Switch does not supply 12V to the CLR (X) the motor relay is not powered and nothing happens.
I hope this will help anybody experiencing the same or other lighting problems!
Shark greetings
Paul
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Join Date: Aug 2010
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Posts: 17
Default Porsche 928S2 (1984) Combination Light Relay
Hello Shark Lovers,
Last year, it happend once with my 1984 S2, that I turned the lights On and nothing happend. The lights didn't pop up and didn't turn On. I cranked them up mannually and they turned On. I drove away and the lights worked fine, when I switched them Off they went out and down. So I turned them On again they worked as advertised. A bad contact maybe?? I finally forgot all about it.
Yesterday night however, I turned the lights ON and they went On, but didn't pop up. What the heck??? Some Heavenly lights on a shark? Then slowly they popped up, first half way and then fully. I drove home and turned them Off and On, and again and again they worked as advertised.
I searched all English and German 928 forums, and read about all sorts of problems with the lighting system, but nobody ever explained how the Combination Light Relay / Motor switch works (to complicated). So I tried to figure it out myself (How I love those crumpy 928 schematics). It took me all night, I still don't know what the heck is/was wrong with my lights, but beneath is how I think the system should work. If anyone has any additions / suggestions please let me know, also if somebody figured out the inside (electronic logic) of the relay, please show me. I don't want to break open my relay if it is working (most of the time?).
Porsche 928S (1984) Combination Light Relay (CLR) XIX-XX
This CLR has three functions:
1) Operate the Concealed Headlight Motor to go Up and Down.
2) Operate the Headlights ON and Off.
3) Operate the High/Low beam function of the Headlights.
To do this the unit has three relays and some simple electronic cirquitry to perform logic functions when operating the 3 relays. The motor relay also has some sort of spark protection (capacitor?).
The CLR has 12 contacts:
1) 30bM Supplies 12V to the Motor Switch (30b) to turn the lamps down.
2) 30b Receives 12V from the Light Switch only in position 0 (All lights OFF)
3) X Receives 12V from the Ignition Switch postion X (12V in position I and II)
4) 56 Receives 12V from the Light Switch only in position II (main lights ON)
5) 30a Receives 12V from the Battery true 16A fuse 19 (Concealed Headlight Motor)
6) 30 Receives 12V from the Battery unfused to power the head lights
7) 31 Ground connection for electronics and relays inside the unit
8) 86M Receives 12V from the Motor Switch (86) to turn the motor relay ON
9) 30M Supplies 12V to the Motor (30) to make it turn.
10) 86 Receives 12V from the Steering Colum Switch (56a) when Hi beam is selected
11) 56a Supplies 12V to the Hi Beam Lights over 8A fuses 24 (Left) and 25 (Right)
12) 56b Supplies 12V to the Lo Beam Lights over 8A fuses 27 (Left) and 28 (Right)
The Concealed Headlight Motor (30) receives 12V from the CLR (30M) and is connected to ground (31). There is a Motor Switch on the Concealed Headlight Motor, this position switch has three contacts:
1) 30b Receives 12V from CLR to turn the lamps DOWN.
2) 86 Supplies 12V to the CLR (86M) to turn the motor relay ON.
3) 56 Receives 12V from Light Switch (postion II) to turn the lamps UP.
In switch position UP contact 86 is diconnected from contact 56 (30b is still connected).
In switch position DOWN contact 86 is diconnected from contact 30b (56 is still connected).
In all switch positions between UP and DOWN all three contact are connected, therefore one diode is used on 30b to prevent contact 56 from powering it and one diode is used on 56 to prevent contact 30b from powering it. Both diodes only carry the relay drive current (+/- 100 mA not the motor current).
If the 56 diode would break (open cirquit), the lights will not come up. If the 30b diode would break (open cirquit), the lights will not go down. If the 56 diode would short cirquit, the lights will probable come down when commanded but could maybe come back up again immediatly afterwards. If the 30b diode would short cirquit, the lights will probable come up when commanded but could maybe come back down again immediatly afterwards.
Basic operation is as follows:
Main Lights ON:
1) When the Light Switch is turned into position II (Main Lights ON), the Motor Switch receives 12V (56). When the lights are not Up, the switch (86) then supplies this 12V to the CLR (86M) to turn the motor relay ON.
When the CLR (X) also receives 12V from the Ignition Switch postion X, the internal logic will:
2) Turn the motor relay on (30M) and supply 12V to the Motor (30) which will start turning untill the Lights are UP and the Motor Switch 86 disconnects from 56.
3) Turn the light relay on and supply 12V to the Hi/Lo relay, which will turn ON the Lo Beam (56b) or the Hi beam (56a), when it receives 12V from the Steering Colum Switch (56a).
If the Ignition Switch does not supply 12V to the CLR (X) the motor relay is not powered and nothing happens.
Park Lights ON:
When the Light Switch is turned from position 0 into position I (Park Lights ON), the Motor Switch will not receive 12V (56). When the lights are not Up, the switch (86) will Not supply 12V to the CLR (86M), the motor relay will not turn ON and the lights stay Down.
When the Light Switch is turned from position II into position I (Park Lights ON), the CLR will turn the light relay Off and the lights turn Off. The Motor Switch will no longer receive 12V (56), but it does not yet receive 12V (30b), so the Motor will not turn and the lights stay Up.
Lights OFF:
When the lights are Up, the Motor Switch (30b) will receive 12V from the CLR (30bM), the motor relay will turn ON and the CLR (30M) supplies 12V to the Motor (30) which will start turning untill the Motor Switch (30b) disconnects the CLR (86) when the lights are Down.
If the Ignition Switch does not supply 12V to the CLR (X) the motor relay is not powered and nothing happens.
I hope this will help anybody experiencing the same or other lighting problems!
Shark greetings
Paul
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928 kiln (10-01-2019)
11-03-2017, 10:41 PM
#5
Team Owner
I have had issues with no low beams and the blue hi beam light stays on.
a good switch was needed.
I had 3 to try,
the original was bad ,
another used one from a parts car was bad,
then finally a new part the lights worked as advertised
NOTE spray some deoxit 5% intro the switch and work it,
I have fixed a few switches by doing this.
NOTE put a towel under the switch so the solvent doesnt get on the carpets.
a good switch was needed.
I had 3 to try,
the original was bad ,
another used one from a parts car was bad,
then finally a new part the lights worked as advertised
NOTE spray some deoxit 5% intro the switch and work it,
I have fixed a few switches by doing this.
NOTE put a towel under the switch so the solvent doesnt get on the carpets.