Rev 1 NA - Tachometer Issue - Please!!!!

[gtech]

Hi People,

Well this fault has had me pulling my hair out and driving me insane.

The tachometer started playing the idiot the other week, bouncing all over and then finally stopped all together.

Well found out that the signal wire is the BLACK wire from the ignitor (I believe also the Red/White cable from Pin 11 of the 22 pin connector on the ecu also does RPM)

Anyway did a continuity check from the ignitor to the Tacho head and that tests fine, although when you put a digital mulimeter on the black wire it just shows a constant 14.** Volt, I would of expected fluctuation as its the RPM signal wire ??? so baffled there.

Anyway been through everything I cannot get the damm thing to work,.

Any Ideas???? Am I looking at the correct wire???? anything would be appreciated.

Thanks

Graeme

[Mr2Fixer]

Hmmm, if this happened to me, I'd:

(1) unplug and replug all connectors involved. A crusty connection could be the cause.

(2) buy a salvaged guage cluster off Ebay and swap tachometers.

(3) check the resistance on the two hall effect generators in the Distributor. They should be between 140 and 160 ohms.

Without a Tach signal the car would at most idle, if run at all. So your ECU and Ignitor must be OK if the car still runs good.

[gtech]

Hi Mr2Fixer :-) cool name.

Well have unplugged every connector I could find and checked all them, in fact did the whole loom from the engine bay to the cluster.

Just waiting for a salvage tacho to be sent to me.

Where/which are the "Hall Effect Generators" on the dizzy, have multimeter, which is best way to test them....getting slightly beyond me there, but will tackle it, if you could oblige with some instructions...

On the tacho head, there are three connectors:

IG+ IG- S

I assume IG+ is a 12v Feed, IG is Ground S is Signal,

That being so, could I not just supply a ground and voltage to the head I will get and link the "S" straight into the BLACK wire from the Ignitor....Just to make sure all works at that point???

Your advise is much appreciated.

Graeme

[gtech]

Further to above...Have been looking at some diags and I MAY have viewed this the wrong way.....

The BLACK wire coming from IGNITOR which goes to the Tachometer, I assumed that was OUTPUT from IGNITOR, when in fact if i read correctly its OUTPUT from TACHO to the IGNITOR which is why it measured 14.* volts instead of fluctuating.

Is this correct.

if so, where does the RPM signal originate from, the diags shows:

Tacho receiving info from the Speed Sensor...Where would this be on a Rev 1 3SGE (Cable driven speedo) ???

The BLACK wire in the ignitor.... is this an INPUT or OUTPUT as it measure 14+ volts. IF this wire developed a problem in the ignitor would this cause a problem with running.

Thanks

Graeme