digital clock connector pin id

sdelasal · Post by **sdelasal** » Tue Nov 23, 2010 6:50 pm

Can anyone tell me what the 4 connector pins should lbe wired to? The brown is ground. One is 12V continuous, one is sidelights - that leaves one other ... and I don't know which pin is which. The Haynes is useless, it actually shows 5 pins on the clock in one of the diagrams. Archives don't help either.

Steve

Post by **mat_fenwick** » Tue Nov 23, 2010 10:26 pm

If you have a multimeter you can check which are which - there should be about 120 ohms between ground and the ignition feed (which will change to infinate resistance when the bulb is removed). There will be a higher resistance than this between ground and the sidelight supply, again changing to infinate when the bulb is removed. The other terminal will be the permanent 12V feed, the resistance between this and ground will not be changed by removing the bulb.

sdelasal · Post by **sdelasal** » Tue Nov 23, 2010 11:26 pm

Matt - relative to ground on pin#2 (brown), measurements are:
1- Open loop
3: 120-ohms - goes open loop if bulb is removed
4. Open loop.

so i'm still none the wiser! Steve

Post by **mat_fenwick** » Wed Nov 24, 2010 9:04 am

mat_fenwick wrote:120 ohms....There will be a higher resistance than this between ground and the sidelight supply

Sorry, ignore that statement, it isn't correct. (After coming back to it I can see I wasn't thinking very logically

)

I'll try and check the wiring on the car today.

electrokid · Post by **electrokid** » Wed Nov 24, 2010 10:12 am

Another way is to test for volts rather than ohms...

Get a meter or test bulb and connect one side to a part of the car's bodywork.
Switch on ignition and sidelights.
Probe all 4 connections with the other end of the test bulb or meter.

The connection that doesn't read 12v or cause the test bulb to light is ground / 0v.

Switch off the sidelights and re-check - the connection that was 12v before and is now dead is the sidelight connection.

Switch off the ignition and re-check - the connection that has just gone from 12v to zero is the ignition.

And the one that is still 12v is the permanent 12v from the battery (and is routed via fuse 8 according to the drawing).

Hope that helps.

Post by **mat_fenwick** » Wed Nov 24, 2010 10:44 am

I'd assumed (not sure why now I look back on it!) that Steve had the clock and was retro fitting it in a car without the wiring.

electrokid · Post by **electrokid** » Wed Nov 24, 2010 11:20 am

'Tis indeed possible - in which case volts won't be available

Post by **mat_fenwick** » Wed Nov 24, 2010 11:50 am

Well, seeing as I'm nice like that, I've taken the clock out (and found a 1 Euro cent coin in the process

) to measure the voltages.

No. 1 is the permanent 12V feed, 2 earth, 3 ignition 12V and 4 sidelight 12V.

sdelasal · Post by **sdelasal** » Wed Nov 24, 2010 2:40 pm

fantastic - Thanks Mat - This is for a potential retrofit by the way for if/when I get the necessary engine sensor to drive the tachometer - thought'd i'd get the wiring all in place whilst it's all opened up. Steve

electrokid · Post by **electrokid** » Wed Nov 24, 2010 7:00 pm

Well done Mat

I'd spend the Euro fairly soon just in case