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wiring a rev counter
Posted: 26 Jan 2014, 10:27
by rallye69
thinking of getting a 2nd hand vdo rev counter , how easy is it to wire on t25, done it on a Golf mk2 years ago ?
Re: wiring a rev counter
Posted: 26 Jan 2014, 10:36
by itchyfeet
Easy
Any Rev counter needs fused ignition 12v and ground which you can pick ip from many places but stereo is easy
Then you need the feed from the negative of the coil, this is green and goes to the multiplug on the dash and also via the fusebox easiest to use a scotchloc on that
If you drive at night you may want to wire up the backlight to the sidelights
Re: wiring a rev counter
Posted: 26 Jan 2014, 10:46
by kevtherev
Or if it's a derv then the alternator for the trigger wire
Re: wiring a rev counter
Posted: 26 Jan 2014, 10:52
by rallye69
cheers, just need to find a decent one now
Re: wiring a rev counter
Posted: 26 Jan 2014, 11:06
by MidLifeCrisis
Not sure that an '81 will have the wiring for the rev counter ...... I know my '84 does not .....
Has anyone got a nice clear pic of where the correct connection on the coil is?
Re: wiring a rev counter
Posted: 26 Jan 2014, 11:24
by itchyfeet
Ok never occured to me it wasn't there on early vehicles
You don't really need a pic there are only two terminals on the coil
One is black and has ignition 12v and connects to the + terminal the other is green and connects to the - terminal
Its the green - you want
The green is switched to negative by the ignition module ( or points on a 009) and each time its switched to ground a spark is produced (actually when its disconnected spark is produced)
Rev counter just counts these switching cycles
As said diesels don't have coils so the alternator generates a signal for the revcounter
Re: wiring a rev counter
Posted: 26 Jan 2014, 12:23
by kevtherev
rallye69 wrote:cheers, just need to find a decent one now
I fitted one
from Demon Tweeks, eaasy fit
Re: wiring a rev counter
Posted: 26 Jan 2014, 12:45
by Tufty_B
I'm also thinking of adding a tacho, but I was looking at replacing the right hand clock in the instrument pod rather than adding an additional pod/clock.
I'd like to know people's reasons for choosing to add a standalone tacho rather swapping out the clock in the existing pod, is it just the cost?
Re: wiring a rev counter
Posted: 26 Jan 2014, 13:58
by kevtherev
Nope it's a nightmare.
Re: wiring a rev counter
Posted: 26 Jan 2014, 14:13
by itchyfeet
snap
no holes drilled position
Re: wiring a rev counter
Posted: 26 Jan 2014, 23:38
by ScienceBoy
Where's a decent place to get a meter? They all seem to cost a bomb.
Re: wiring a rev counter
Posted: 27 Jan 2014, 00:18
by Tufty_B
kevtherev wrote:Nope it's a nightmare.
Is it not just a case of taking the instrument pod off and unscrewing the back and swapping the units over?
Re: wiring a rev counter
Posted: 27 Jan 2014, 06:12
by itchyfeet
ScienceBoy wrote:Where's a decent place to get a meter? They all seem to cost a bomb.
Assume you mean rev counter paid £40 for that tim one off ebay new with postage
Re: wiring a rev counter
Posted: 27 Jan 2014, 07:27
by kevtherev
Tufty_B wrote:kevtherev wrote:Nope it's a nightmare.
Is it not just a case of taking the instrument pod off and unscrewing the back and swapping the units over?
to fit it yes.
to make it work no.
Re: wiring a rev counter
Posted: 27 Jan 2014, 20:13
by Tufty_B
kevtherev wrote:Tufty_B wrote:kevtherev wrote:Nope it's a nightmare.
Is it not just a case of taking the instrument pod off and unscrewing the back and swapping the units over?
to fit it yes.
to make it work no.
Looking at the Bentley, it seems all the tacho needs on the T14 plug are connections:
3 Earth - brown
8 Ignition positive - black
9 Ignition coil - green
I guess in reality, actually wiring it up could be a mare.
