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Hazard Warning Issue

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Old Oct 21st, 2020, 15:14   #21
Othen
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Originally Posted by MrBloxz View Post
Ok, I've checked the wiring diagram that you kindly posted and things aren't adding up, the fuze usages don't correspond to what is on the back of my fuze box cover and I'm looking at the back of my hazard warning light and the colours of the wires also don't add up, I have a 1993 Torslanda, are they known to be so different?

Attachment 131234

As for the buzzing, all the noises are coming from the flasher relay for the hazards/indicators, there is no other relay making noise and I can't find the seatbelt warning buzzer relay anywhere
Okay. Don't worry about fuse numbers and wire colours changing between model years, manufacturers do that all the time and Volvo is no more guilty than most. The way the wires run will hardly change between years though, so you can easily identify what is running to where by resting for continuity/discontinuity.

The fuse numbering on the back of your fuse box is almost certainly right for your car, so use that to identify what goes where - there will be a 1:1 correlation (more or less) with the cct diagram on pp 96 of the wiring diagrams:



Let's be more methodical and see if we can find the fault.

First of all let's think about the warning buzzer that someone told you to change: this operates under the following conditions:
a. keys in/door open.
b. Lights on/door open.
c. Keys left in car.

... so the first thing to do it check it works under these
- none of these are anything to do with the fault you have reported, so we may almost certainly discount the buzzer relay.

So, the problem almost certainly isn't with the warning buzzer cct, it is with the hazard flashers cct. Someone (Bob I think) mentioned that the seat belt warning should slow down when the hazards are turned on - this is probably because they share a common power supply from fuse 13 (it might have a different number on your car, but it will be easy to work out what that is), so they interfere with each other. Don't worry about that.

Again thinking methodically, do the left and right side indicators work normally? If they do then the indicator relay is okay (all it does is turn on and off, it doesn't matter which cct that is for). If the left and right indicators don't work properly then change just that relay and the problem will probably be fixed.

So, assuming the left and right indicators work properly, what else is left to be faulty: either the hazard switch (someone, I think Bob talked about this - the switch will be easy enough to check electrically - it only does one thing - off and on), or there is some wiring between that is playing up (maybe chaffed through to earth on the body).

Once you have checked the switch for continuity/discontinuity and either fixed it or discounted it, the only thing left is those bits of wire. There are only 6 of them (look at the diagram I've left you above) - you can probably discount the bottom 4 if the left and right turn signals work properly, which leaves the two power cables at the top - if I were a betting man (which I am not) I'd go for the one that is common to the warning buzzer fuse (I think I said this several posts ago). Checking each wire for continuity/discontinuity and to earth should tell you what is wrong if one of the other things I mentioned in the process has not already led you there.

All this is just logic - nothing to do with owning Volvos for 50 years (which I have not) or being a member of the VOC or this forum since Abraham was a boy. My only relevant qualifications in this respect are that I'm an electrician, have been fixing cars and bikes for decades and have a degree in physics. I will not be offended in any way if you want to ignore all the above and just randomly change bits to see if they work, but I have spent long enough on this problem.

I hope you fix your car.

Alan

Last edited by Othen; Oct 21st, 2020 at 15:18. Reason: Spelling error.
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Old Oct 22nd, 2020, 14:34   #22
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Okay. Don't worry about fuse numbers and wire colours changing between model years, manufacturers do that all the time and Volvo is no more guilty than most. The way the wires run will hardly change between years though, so you can easily identify what is running to where by resting for continuity/discontinuity.

The fuse numbering on the back of your fuse box is almost certainly right for your car, so use that to identify what goes where - there will be a 1:1 correlation (more or less) with the cct diagram on pp 96 of the wiring diagrams:



Let's be more methodical and see if we can find the fault.

First of all let's think about the warning buzzer that someone told you to change: this operates under the following conditions:
a. keys in/door open.
b. Lights on/door open.
c. Keys left in car.

... so the first thing to do it check it works under these
- none of these are anything to do with the fault you have reported, so we may almost certainly discount the buzzer relay.

So, the problem almost certainly isn't with the warning buzzer cct, it is with the hazard flashers cct. Someone (Bob I think) mentioned that the seat belt warning should slow down when the hazards are turned on - this is probably because they share a common power supply from fuse 13 (it might have a different number on your car, but it will be easy to work out what that is), so they interfere with each other. Don't worry about that.

Again thinking methodically, do the left and right side indicators work normally? If they do then the indicator relay is okay (all it does is turn on and off, it doesn't matter which cct that is for). If the left and right indicators don't work properly then change just that relay and the problem will probably be fixed.

So, assuming the left and right indicators work properly, what else is left to be faulty: either the hazard switch (someone, I think Bob talked about this - the switch will be easy enough to check electrically - it only does one thing - off and on), or there is some wiring between that is playing up (maybe chaffed through to earth on the body).

Once you have checked the switch for continuity/discontinuity and either fixed it or discounted it, the only thing left is those bits of wire. There are only 6 of them (look at the diagram I've left you above) - you can probably discount the bottom 4 if the left and right turn signals work properly, which leaves the two power cables at the top - if I were a betting man (which I am not) I'd go for the one that is common to the warning buzzer fuse (I think I said this several posts ago). Checking each wire for continuity/discontinuity and to earth should tell you what is wrong if one of the other things I mentioned in the process has not already led you there.

All this is just logic - nothing to do with owning Volvos for 50 years (which I have not) or being a member of the VOC or this forum since Abraham was a boy. My only relevant qualifications in this respect are that I'm an electrician, have been fixing cars and bikes for decades and have a degree in physics. I will not be offended in any way if you want to ignore all the above and just randomly change bits to see if they work, but I have spent long enough on this problem.

I hope you fix your car.

Alan
Thanks Alan

I've put a meter across the switch and continuity seems ok, however I noticed when connected the power pins were pulling 12v but when you switch the hazards on it goes down to around 4v, I'm guessing this means there is a short in the wiring somewhere?
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Old Oct 22nd, 2020, 17:48   #23
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Thanks Alan

I've put a meter across the switch and continuity seems ok, however I noticed when connected the power pins were pulling 12v but when you switch the hazards on it goes down to around 4v, I'm guessing this means there is a short in the wiring somewhere?
Ah, just as I thought: that explains the buzzing sound you are hearing, it isn't a buzzer at all but the flasher unit trying to flash but not having enough current going through it to open the contacts fully.

Okay, so you are losing 8v somewhere, you just have to find it (could be the switch, a short circuit or an earth (-ve return) problem with the wiring.

Check the voltage at pins 30 and 15 (to earth) they should both be 12v (30 should be permanent, 15 is switched by the ignition), then check the potential between them both with the switch open and closed to make sure there is no leakage happening inside the switch.

Now try the output to pin 49 with the external wire to the flasher removed - this may be what you have measured already - it should be 12v both open and closed, but there should be a jump between as the switch goes from pin 30 to 15. If it isn't then the fault is inside the switch (the external wire being disconnected). Change the switch and it should work.

Pin 49 gives 12v then the fault is probably in the wiring, fortunately there isn't much of it to check.

Einfach? Just use logic like the above to narrow down where the fault can be until you find it, all the information you should need is in the cct diagram above.

It shouldn't take long with a meter - just be methodical and eliminate one thing at a time.

Good fortune,

Alan

PS. Having thought about it: the most likely fault is a spurious high resistance somewhere, maybe the sliding contact in the switch, one of the contacts or a joint.

Last edited by Othen; Oct 22nd, 2020 at 19:21.
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Old Oct 22nd, 2020, 21:43   #24
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PPS. I just had a idea to check whether the hazard switch is at fault whilst watching the Giro highlights (come on Ineos Grenadiers!). If you don't have a spare switch to swap out then disconnect the old one from the loom and connect:

a. a jumper from terminal 30 (be careful, it is permanent live) to terminal 49 of the block, and
b. jumpers from terminal 49a to both the L and R terminals (again on the loom, not the switch).

That will replicate the switch being closed - if the hazards work and the flasher relay stops buzzing (starts clicking slowly) then you will know the issue is with the switch. Einfach nicht wahr?
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Old Nov 5th, 2020, 08:34   #25
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Thanks Alan

I've put a meter across the switch and continuity seems ok, however I noticed when connected the power pins were pulling 12v but when you switch the hazards on it goes down to around 4v, I'm guessing this means there is a short in the wiring somewhere?
Did you get this sorted out?

Alan
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