Hazard Warning Light fault

[davep]

My pre-cat Griffith failed its MOT today, the hazard warning lights do not work with the ignition off. I've checked the wiring to the dash switch and I'm a bit confused. There's four wires to the twin reed On/Off switch: double red (battery 12V, sourced from dash supply), single red (battery 12 V), brown/black (12V switched from ignition), brown (output). Does anyone that's done a dash removal have a record of how their Hazard Warning light switch is wired?

The hazards work OK with the ignition switched On, and they work OK when arming and disarming the alarm, therefore the flasher relay on the main relay board is OK (indicators work OK). The relays on the relay board behind the dash are OK continuity wise.

The bible talks about two diodes that seem to isolate the two 12V feeds for the flasher and hazard warning circuits has anyone had problems with these?

Any help would be appreciated.

[Hedgehopper]

No idea what your hazard light problem is but two things come to mind...

1), Has it ever worked with ignition off before, or is this a recent fault?

2), You say that your brown/black wire is ignition live. This may be why it doesn't work with the ignition off.

Just me guessing as you've had no other help.

[Loubaruch]

From some rough notes made years ago when I removed the dash the connections to my hazard switch are:

Red, Presumably Live +12v
Black/Brown, presumably connection to the flasher unit
Green/White, LH indicators
Green/White, RH indicators

There could be diodes somewhere for isolation, have no idea where these are located.

My car is a 1996 500 so could well be different.

Unfortunately Steves Bible does not seem to include a hazard switch on his circuit diagram.

Best of luck!

Edited by Loubaruch on Saturday 12th October 19:09

[davep]

Thanks for the input guys.

From the bible circuit diagram there should be two 12V feeds, one from the ignition and one from the battery, two diodes isolate the ignition circuit from the hazard 12V when the switch is On and ignition Off. Both flasher and hazard circuits are working Ok with ignition On, so both sets of relays are working. One side of the switch is wired with brown/black to brown the other double red to red, both 12V permanently On, which doesn't make sense. Why connect 12V to 12V? I think I'll have a closer look at the loom and see if there's another brown buried in there.

I'm not sure if the hazards have ever worked with the ignition Off. But the problem has never been flagged in previous MOT tests so I'm assuming they have worked correctly in the past.

[Mr Jenks]

Pic of my `99 500 dash wiring, not much help because colours are different to the ones you have.


There are many ways of wiring the hazard lights switch, depends on how many relays are used, this is an early version I think from a Chim

[davep]

Thanks Mr Jenks.

I've been through the circuit and the switch has been connected up incorrectly (bodged for an ignition 12V supply to both flasher unit and hazard relay) and I've discovered why. When I connect the switch correctly there's a huge current drain in the dash's battery 12V supply circuit. So now it's hunt the short time, great!

[Hoover.]

^^^^ problem found so good enough to botch to get MOT... n then spend time sorting issue

[davep]

Well that was a weird one. I've got 'Glow when Blown' fuses on the car and the 10A fuse for the Dash was glowing when the Hazards were switched On but not glowing when switched Off, however the clock and dash lights which are on the same 12V battery supply were working fine (until the Hazards were switched On). So the fuse was passing sufficient current for the clock and dash lights to work but with the extra current load of the hazards (370mA) the fuse would go to a 'blown' state sending the circuit open circuit. So a standard fuse has gone back in and the problem is fixed.

[EGB]

davep said:

Well that was a weird one. I've got 'Glow when Blown' fuses on the car and the 10A fuse for the Dash was glowing when the Hazards were switched On but not glowing when switched Off, however the clock and dash lights which are on the same 12V battery supply were working fine (until the Hazards were switched On). So the fuse was passing sufficient current for the clock and dash lights to work but with the extra current load of the hazards (370mA) the fuse would go to a 'blown' state sending the circuit open circuit. So a standard fuse has gone back in and the problem is fixed.

Glad prob is now fixed. What was the amp of the standard fuse?

[davep]

I've put a 10A fuse in. It looks like the clock was drawing current via the fuse's glow lamp even though the fuse element itself was blown. Couple that with an incorrectly wired switch and you have confuse a Griff owner.