Tach woes

[bottlecapE30]

my 2.7 had the old 4500rpm redline tach in the cluster and i got a 7000 rpm tach out of an old cluster but when i installed it the needle still moves at the same rate as the old 4500rpm tach what do i have to change to make the tach read the right number of rpms?
any clues?

[Brianmoooore]

Try a 6 pot "i" coding plug for a start.

[Chris]

Sorry to sound dumb (i'm new) but what is a 6 pot "i" coding plug??

[bottlecapE30]

i have the same question i have nearly zero knowlage of electrionics
sorry

[DanThe]

The coding plug fits in the front of the clocks on the right hand side, clocks dont need to be removed to change it, basically just tells the tach how many cylinders your engine has so it gives the correct reading.
ie. 4 cyl coding plug + 6 cyl coding plug

[Brianmoooore]

ie. 4 cyl coding plug + 6 cyl coding plug

And it looks like, 325e coding plug.
You can get at the coding plug by taking off the little trim piece just above the steering column shroud. Held on by two "finger" nuts up behind the dash.

[Chris]

All makes sense now, cheers. Wots the 'i' for then? lol

[bottlecapE30]

Thanks so much guys
all the best

[Brianmoooore]

[quote=" Wots the 'i' for then? lol[/quote]
Really have to spell it out for some people!
Look at the badge on the RH side of your boot lid!