posted by
someone claiming to be Boris
on
Fri May 31 17:15 CST 2024 [ RELATED]
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When I turn the headlight switch on I get no low beams. If at this point I pull on the high beam lever, high beams come on and stay on as long as I am pulling on the level. If I let go, high beams go out.
If I put the ignition key to position I and then turn the parking lights on, that will work. At the same time the dash is illuminated as well. If I turn the light switch to engage the headlights they will not come on, and the dash illumination goes dark. The bulbs for headlights are fine...
The fuses from 19 to 22 are fine too. Fuse 26 (light switch) is fine also.
Any ideas?
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Hi Boris,
Two culprits are the the Main Light relay In the main fuse block marked
"104 106" This solid state relay provides power to the low beam fuses.
The main light switch enables the relay.
Bill
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Do you mean light relay 9148880 ?
On the side it says 104 108.
The headlight switch has power on it, it can turn parking lights on.
I suppose it can still be bad.
Is there way to determine whether it is the switch or the relay?
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Hi Boris,
Yes the lamp relay is "104 108" ("2/1"in the schematic)
The part # for 850 is 3523200
I'm using the schematic for a 95 850 which is likely the same but no guarantee.
You should dig up the Volvo wiring diagram for your model year to troubleshoot
with high confidence. Maybe you'll find it for free?
When you pull the dual relay 104 108 are you able to read connector pins
where the relay plugs in?
You can read pin numbers on the dual relay,
pin 15 is the +12V control line from the light switch for low beams
make sure the headlight switch sends +12V to pin 15
This may help.
Trying to troubleshoot wiring requires the Volvo Wiring diagram for your model year.
Give an email address and I'll send you the headlight wiring info that includes the relay and harness pinout from the 850 book.
Bill
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Thanks B.B.
I appreciate your feedback.
You call this relay "dual". Why? Does it control headlights and signal lights?
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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The lamp controller has two sets of switches with multiple inputs.
Volvo has different lighting circuits for different countries.
So one answer doesn't fit all.
That's why you need the Volvo wiring diagram for your model year.
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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I was able to find and download wiring diagram book for my exact model.
Now if I can just find my reading glasses...
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Hi Boris,
There's no substitute for the Volvo wiring greenbook.
Please share the link so others can grab that manual, Borko for instance.
Thanks, Bill
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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I've been reading the wiring manual...it's only about 320 pages of technical lingo and no English description of part names. I like the challenge but this will be a PITA. I discovered something interesting. My headlight switch is removed, and on my work bench. I have no keys in the ignition. If I pinch the low beam contacts on the headlight relay I get the low beams.
Is it normal to have power on the headlight relay all the time?
That being said, which is the bigger culprit now, the headlight switch, the headlight relay, or perhaps something else? All the fuses are fine. The plot thickens...
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Hi Boris,
I don't have the correct manual here, and asked you for the link to get it.
Look at the last few pages of the manual for the pages that tell you what the
schematic items are.
You should locate the low beam pages for your car to understand what happens to
run the low beams. There will be a 12V line from the main light switch to the lamp controller and output from the controller to the low beams.
The Volvo schematic give you the relay/controller socket pin numbers AND the
harness connector pin numbers to aid testing with your VOM. Note the Bulb out sensor is in series with the low beams.
If you have a junk yard near you you can get a light switch and controller cheap.
If you go to the dealer bring a fat bankroll and take a strong sedative before you hear the price.
Cheers, Bill
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Wiring diagram:
https://mega.nz/file/Bu5xDKTL#CHtqU8IOAkieViVjPNZMRR_MMmOmFID1KOin9bLmA7A
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Hi Boris,
Thanks for the nice manual on a creepy cloud server, where did you find it?
First thing to do is to check F-5 (Fuse) it looks like you didn't check the lamp
controller fuse. Don't pull the ATC fuses to check, probe the top legs (2)
and confirm +12V on each side... easier and you can't lose the fuse.
A dead Fuse 5 will shoot down your lights, but not the high flasher.
Check the ground connection 31/51 to the lamp controller pin 8A
see pg 110-111
See if you get joy, Bill
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Ahoy Boris!
Where did you go?
Did you solve your issue with Fuse-5 ?
Please report what solved your problem and get 10 points.
Thanks, Bill
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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There was no problem with fuse #5 or any other.
All fuses are OK, all relays are OK.
Mysterious intermittent electrical problem remains.
I can drive off and everything works fine, all the electrical appliances work perfectly. Then, sometimes, I will start the engine, it runs fine, but problems return:
Can't move the shifter from P to R or from P to D unless I use the shiftlock button to release it.
No signal lights, no head lights, no brake lights...
Then, at next stop, it may all be fine again...I suspected the ignition lock. But wiggling the key does not change anything.
Very frustrating...
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Hey Boris!
You disappeared for weeks. I was worried that you were conscripted and sent to the front line in the temporarily occupied Ukraine. I'm glad you're OK.
Now you indicate another clue, the shift lock fails with the lights, eh?
Relay 2/26 is common to the lights and shift lock, both are switched by the ignition switch.
And you checked all the fuses and relays and none are intermittent or have
a loose connection. You can have relays go intermittent, and also
relay socket pins can get loose, usually after several removals by enthusiastic brutes that can rock the relay and damage the socket pins.
It's a good idea to take a 1/4" male spade connector and crimp it on a solid
copper wire so you can test each relay socket pin to see if it is tight.
If a pin is loose then it needs to be removed and tightened or replaced.
If you get to that point I'll tell you how to do it.
Use Penetrox-A, anti corrosion zinc paste, on female connectors.
Volvo had a connector grease Part # 1161417-9 if you can't find Pentrox-A.
Here's what to do: The next time it fails be ready with your VOM to measure
+12V at the top of Fuse 26 with the Key remaining in KPII run position.
Look carefully at the top of your ATC fuses, you can probe each leg of the fuses. Ground your meter at the Negative battery terminal.
No +12 Volts then it's a bad relay 2/26 marked "106", or the ignition switch.
Remove 2/26 and measure +12V at pin #2 with your ground lead on pin #4
If you get +12 your ignition switch and ground 31/50 is OK.
measure +12V at pin 1 to pin 4. If that's OK try another relay
If both of the above tests get no +12V, try the test again except ground your meter to the Negative of the battery, and if both are +12V check for a crappy ground 31/50 which is under the main fuse box, lower level, in the engine bay.
Use conductive grease nickel or copper anti seize or Penetrox after cleaning up the connections.
Report back what you find, Bill
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Thanks Bill. You gave me a lot of good tips.
Intermittent electrical problems are very hard to figure out.
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Do you mean light relay 9148880 ?
On the side it says 104 108.
The headlight switch has power on it, it can turn parking lights on.
I suppose it can still be bad.
Is there way to determine whether it is the switch or the relay?
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Do you mean light relay 9148880 ?
On the side it says 104 108.
The headlight switch has power on it, it can turn parking lights on.
I suppose it can still be bad.
Is there way to determine whether it is the switch or the relay?
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