Digital clock - problem

Forum: 

The digital clock in my 1988 F75 doesn't keep time while the truck is turned off. At first I thought this was the clock fault but I got a replacement and the behaviour is exactly the same. Every time I start the engine the watch switches on at 1:00...

I have checked the technical manual to try and find an answer to my problem, but my electrical knowledge isn't too great. Maybe you can help me?

Here's the page manual regarding the digital clock:

http://img125.imagevenue.com/img.php?image=25062_clock_circuit_122_974lo.jpg

Sounds like your continuess

Sounds like your continuess feed has gone. May only be a blown fuse. Take the clock out, and un-plug it. Then using a multi meter you should be able to work out which wire to the plug is earth (negative / - (offten black & white)), which is live (+) when the ignition is on only and which is live when the lights are switched on only. The remaining wire should be liva all the time.
If you can't find a blown fuse, or other obviouse problem, you can take a new permonent feed from somewhere els (back of the fuse box maybe) and run it up to the plug for the clock.
Without this permanent feed there is no power to keep the clocks memory, so it goes back to factory settings every time you switch on the ignition.

Any veiws expresed in this thread by me are purely from my own experience, and (sometimes) falible memory. Hope my comments help, but please don't take them as gospel.

Any veiws expresed in this thread by me are purely from my own experience, and (sometimes) falible memory. Hope my comments help, but please don't take them as gospel.

I had this once. It drove me

I had this once. It drove me mad tracing lines and the like, until one day the battery gave up. Replaced it, and hey presto - one fully functioning clock!

Dave with a Sporty

Dave with a Sporty

That sugestes that the car

That sugestes that the car has a safety cut off on the power? Ie, if the voltage from the battery dropes below a pre set threashold when the ignition is off the power is cut to all standby sistems, to presurve power for starting the engine. Sounds very Japanies!

Any veiws expresed in this thread by me are purely from my own experience, and (sometimes) falible memory. Hope my comments help, but please don't take them as gospel.

Any veiws expresed in this thread by me are purely from my own experience, and (sometimes) falible memory. Hope my comments help, but please don't take them as gospel.

Multi meter

Alright - I shall do what you suggest - since the multi meter has two leads - one of them is supposed to connect to the earth wire and the other to whatever lead I'm measuring, correct?

There are four connections on the back of the clock - the circuit diagram lists them has:

-Earth
-Tail (on/off via light control switch)
-ACC (on/off IG Switch (ignition?)) [CIG 15A FUSE]
-Clock [Lock-dome 15A FUSE]

So basically I'll check 3 connections and two fuses - one of them in the main fuse block at the cowl side of the driver's side and the other, sub fuse block near the battery. Correct?

Clocked

Sounds as if the wiring has been tampered with at sometime, this has been wired through an ignition circuit, and therefore the power is switched off when the ignition is turned off.

As Nev says, try to find the correct wiring by testing for the constant feeds, and not the ignition controlled feeds.

Battery charger.

I agree with Dave. The suspect could be the 12v battery. What happens to the clock's time if you connect a battery charger and fully charge overnight?

If that proves ineffective, remove the clock and connect the supply directly to a multi meter and check for a supply voltage with ignition switched off. No voltage = someone has connected to the ignition supply rather than a 12v permanent circuit. Clock will need a new 12v connection.

Ok - I've checked the

Ok - I've checked the connections with a multi meter.

Here's what I got:

When the ignition if OFF:

Clock (+) - Has voltage;
Tail (+) - No voltage;
ACC (+) - No voltage;

When the ignition if ON:

Clock (+) - Has voltage;
Tail (+) - No voltage;
ACC (+) - Has voltage;

If I turn either of the lights on, I get NO voltage readings on the leads - which is strange because the clock functions normally when I turn the lights on (with the ignition on).

I've also did a visual check on CIG 15A fuse - looked fine. I couldn't find the "Lock-dome 15A FUSE" nor the sub fuse block the technical manual refers to...

Thoughts, anyone?

Quote:
Alright - I shall do what you suggest - since the multi meter has two leads - one of them is supposed to connect to the earth wire and the other to whatever lead I'm measuring, correct?

There are four connections on the back of the clock - the circuit diagram lists them has:

-Earth
-Tail (on/off via light control switch)
-ACC (on/off IG Switch (ignition?)) [CIG 15A FUSE]
-Clock [Lock-dome 15A FUSE]

So basically I'll check 3 connections and two fuses - one of them in the main fuse block at the cowl side of the driver's side and the other, sub fuse block near the battery. Correct?

Voltages.

The diagram is same as for Sportrak.
Do you have access to the previous page 'BE 111' which gives the voltages between terminals when ignition is 'on and off'?

Quote: Do you have access

Quote:
Do you have access to the previous page 'BE 111' which gives the voltages between terminals when ignition is 'on and off'?

No I don't...

On the 1992 Rocky manual:

Terminal____Voltage_______Remarks

CLOCK_______Approx. 12V___At all times

ACC_________Approx. 12V___When IG switch is set to ACC

TAIL________Approx. 12V___When light control switch is turned on

Check Voltages.

Check those voltages - page BE 111. Note Ignition on/off as mentioned.

Have you fully charged the 12v battery or temporary fitted a fully charged replacemend battery

BE 111 on the Sportrak

BE 111 on the Sportrak manual correct?

Quote:
Have you fully charged the 12v battery or temporary fitted a fully charged replacemend battery

No I didn't - I didn't/don't have neither a charger nor a suitable replacement. My battery SEEMS to be ok, but...

Try putting the multi meter

Try putting the multi meter across the battery terminals while someone els starts her up. If the voltage drops a lot (say below 9v), then this would point to a dying batery. This could also be the reason for the reseting clock, as too low a voltage (and therfor current) would have the same effect as no power at all.

I would also try running a temporary wire straight from the batery positive to the clock. If that makes no diffrence try a temp. wire from the Battery negative direct to the clock instead. This could trace the fult to a particular part of the wiring.

Any veiws expresed in this thread by me are purely from my own experience, and (sometimes) falible memory. Hope my comments help, but please don't take them as gospel.

Any veiws expresed in this thread by me are purely from my own experience, and (sometimes) falible memory. Hope my comments help, but please don't take them as gospel.

Problem Solved

My electrician re-wired the continuous lead from another source and lo and behold: a fully functional clock!

Thanks for all the input!

Smile