haygeebaby

Guys
Does anyone know the fix for this?
The clock works fine, but when the headlights are turned on - the clock stops working.
Noticed the other day when driving at night.
Thanks in advance.

pp000830

Hi Hay Gee,
I would replace the related fuses as old fuses can develop oxide on their paddles and clean their socket connections with spray CRC QD electronic cleaner or similar. Then, I would pull the clock and test the ground wire going to it with a volt/ohm meter, the brown wire, and see if it is a good connection to ground. While the clock is out clean its plug and socket with spray electronic cleaner as well. An inexpensive meter is $10 at a discount retailer or online.
https://smile.amazon.com/AstroAI-Dig...UA6/ref=sr_1_5
Follow-up here with the results.
Andy

jay@EZimmoblock.com

The clock mechanism shares the same ground connection as the 2 clock illumination lamps. If those go out at the same time the clock stops, the problem is on the ground side. If they stay on when the clock stops, the problem is on the power side. (The clock gets power from fuse #12). Curious, does the clock adjustment switch move the hands?

haygeebaby

Thanks for the prompt reply gents.
I will check the fuse and ground later today.
The clock switch works when headlights not turned on - but does not work when headlights are on.

haygeebaby

Ok - fuse #12 is fine and neg and pos on the round connector is fine - when headlight switch is on and off.
So - thinking that the problem is with the globes - I started taking a few out and swapping around to test.

I noticed that when light orange bulb is removed the clock works fine.
Put the orange globe back - clock doesn't work with headlights on.
Dam - any ideas guys?

jay@EZimmoblock.com

Very strange. Not sure how the power and ground measurements were made, but if the clock has power and ground, it should work...
Need more info:
1) Does the clock backlight illumination also go out when the clock stops?
2) Does the clock also stop working when just the parking lights are on or do the headlights have to be on?
3) Which bulb exactly did you remove to make things ok - front/rear, marker/directional? Does it work when you remove the left OR right bulb or just one side? Which?
4) Euro car?
5) LHD or RHD?
6) Any work done/changes made recently?

pp000830

Hay Gee & Jay,
A related issue, The solder joints on the circuit board in the clock are a known failure item. Years ago when sorting out an issue I reheated the solder joints on the board and cleaned and bent the lamp contacts to ensure good connectivity to their sockets. I seem to recall the pins that go to the clock have to have their solder joints heated to release the circuit board to work on it. It was easy work with a 25~35 watt pencil-style soldering iron. It didn't take very long to do and will eliminate any suspect issues internal to the clock as the root cause of a clock problem.
Andy

jay@EZimmoblock.com

Andy, yeah, not a bad idea hitting the solder joints with an iron but the correlation to headlights ON is still hard to explain. On RHD cars (which he may have), the clock is on the same ground as the headlights, but even so, I can't explain the behavior.....

pp000830

Assuming the gauge face illumination works properly and lights up the clock when the headlights are turned on:
Im thinkin' that a + trace on the board is open so when the headlights are on the gauge illumination is powered and with it the clock. When the headlights are off there is broken internal to the gauge path to the clock so it stops.
Pulling the board will likely show a broken solder joint or a failed trace to the clock.
Andy

jay@EZimmoblock.com

..Except it's the opposite...the clock STOPS when the lights are on. The suggestion to check clock illumination when the clock is stopped is if they are ON, the ground side of both the clock and the lamps (which they share) is intact. But they get powered differently: the clock is powered by constant +12 (thru F12); the lamps are powered by dimmer R24. So if the lamps work when the clock doesn't, the problem is 12 v to the clock, not it's ground. We'll have to see what OP comes back with. Still can't see the connection to the headlights....

pp000830

Hi Jay,
Yes, I guess my dyslexia is kicking in or maybe a Dotage flair-up,
Andy ;-)