Rev counter fault

[trackerjack]

My Mki tacho does not work, is this common?
Any leccy guru,s got some advice as to where it is connected or is it ecu controlled?

[Richyvrlimited]

trackerjack said:

My Mki tacho does not work, is this common?
Any leccy guru,s got some advice as to where it is connected or is it ecu controlled?

Depends on the car.

Early 1.6 MK1's the tacho signal is sourced from the igniter box (that's a matchbox sized device bolted to the offside drivers wheel arch, in the engine bay). If the tacho has failed it usually means the igniter is on it's way out.

Early 1.8 MK1's the igniter (and tacho pulse) is integrated into the coilpacks. with 1/2 the signal coming from each coilpack. Again replacement would be necessary to fix.

Later 1.8 MK1's (post 1995.5) the tacho source moved to an ECU provided signal.

All MK2's & Mk3's the tacho signal comes from the ECU.

[Oldandslow]

Daft question maybe but does everything else work?

I occasionally blow a fuse that takes out the rev counter, petrol guage and indicators. 10amp in the driver's footwell box.

[trackerjack]

Thanks folks it is actually an early MK1 1.6 and was the blue and white car that was in PPC magazine a few years ago and runs an HSK turbo as they tried to extract the most from an MX5.

I am using it in all its running gear in a lotus seven type car which is 99.9% complete now after 3 years building.
The car ran for the first time in six years last night and sounds glorious and all except the tacho works.

Forgive my ignorance but what does an igniter look like?
I am a coil man and leccy is not my thing.

[trackerjack]

Well replaced the little black igniter with known working one and no change so now it must be a wiring or tacho fault.
Thanks for the help.

[trackerjack]

Phew why are problems so costly in time!!
Changed igniter no change.
Pinched wifes instrument pod from her Eunos and no Tacho.
Checked contact with the bolts that hold the Tacho, which also are the contacts, no change.
Finally looking closely at the igniter it has moulded writing as to the connections and fourth one in labelled "tac" is the wire that I spliced into and ran a separate wire direct to the top connection and nearest the multi plug and HEY PRESTO TACHO WORKS.
It has eaten hours of my time but that is what messing with cars is all about.