CLOCK VDO not working
 

The clock (VDO) on my 1987 volvo 245 was working erratically for quite some time. It was working and stopping without any pattern. Finally it stopped completely and I decided to disconnect it from the cluster to isolate the error. On the back of the clock there are two wires one black (12V) and the other is brown (ground). I connected these two wires to a 12 v DC transformer for few moments and noticed no motion at all. It is appreciated if someone could tell me what could be the problem with this clock and how it can be fixed. Thanks.

"its broken".

Pierce, thanks for your reply. What is the part that is broken? and can it be replaced?

the whole clock is one part. you could open it up and try to repair it, I suppose, if you are a wizard with quartz electric clocks.

get one from the junkyard. Thats the cheap and simple option. Just remember to get a non ABS and non SRS version (nothing 1990+)

why would the clock be different for ABS or SRS?

are we talking about the full sized clock, or the little one used on cars with tachometers ?

No the clocks (full sized ones) will be exactly the same. Not quite sure what happens if you put an ABS/SRS cluster into a non equipped vehicle. I did the opposite (non SRS cluster into SRS vehicle) and the SRS light came on when I swapped back to original cluster.

Maybe a DTC could be stored related to cruise control or something?

ah, IIRC, ABS have a different speed ratio as there are more ticks on the encoder wheel in the rear end, so an ABS speedometer will read very slow with a non-ABS differential, like less than half your actual speed or something. ditto the odometer.

the 240/740/940 ABS is 3-channel, not 4-channel. the rear wheels are lumped together and use the speedometer pickup.

^^ exactly. The speed will be off by about 5mph (atleast that's what I found by running the 2 clusters on the same stretch of road and measuring the corresponding speed on GPS - which is obviously not very "scientific")

I would expect it to be quite a lot more than 5mph, unless you measured that at like 10mph. I'm not 100% sure offhand, but I thought the non-ABS were like 8-10 pulses/turn, while the ABS were more like 25 pulses/turn. this would make the error 2.5X or 3X or something, so it would read 20 or 25mph when you're going 60MPH

yeah it was in a parking lot. So not very accurate haha

Thank you gentlemen for all your feedbacks. What I did is that I opened the clock and found one of the capacitors is shorted. I replaced it and the clock is running just fine.

awesome!