E30 Tacho' question.

[Nobody You Know]

Evening all.

I bought an F Reg' 320i Touring a few weeks ago, the tacho was not working but the previous owner kindly gave me a replacement tacho' with the car.

Today I went to replace the tacho' (just the dial not the whole instrument pod). I replaced it no problem but the tacho still does not work, the mpg gauge under the tacho which is part of te same dial worked on both tacho's.

I noticed though that the instrument panel had 3 electricl connector ports Left = White, Middle = Yellow, Right = Blue but there are only plugs on the loom to fit into the blue and white connections.

Really I'm wondering did the 320i actually have a tacho? And has somebody later fitted an instrument pod with a tacho that there is no wiring for? Should there be a Yellow plug coming from the wiring loom to fit into the yellow connector on the back of the instrument pod?

Or is this correct and there is a wiring fault somewhere further down the loom or a bad sensor causing the tacho not to work?

I cannot believe that both Tacho's are broken in exactly the same way.

[Nobody You Know]

Anyone?

[E30M3SE]

320i's all had tacho's the missing plug is for the OBC iirc, am guessing that your car only has an analogue clock.

You may well have an instrument cluster circuit board problem which is why the tacho does not work, quite common.

[VX Foxy]

Could be a problem with the battery on the instrument pcb. Quite easy to replace.

[T89 Preparation.]

VX Foxy said:

Could be a problem with the battery on the instrument pcb. Quite easy to replace.

Where abouts is this battery?

[E30M3SE]

T89 Preparation. said:

VX Foxy said:

Could be a problem with the battery on the instrument pcb. Quite easy to replace.

Where abouts is this battery?

Soldered to the Si board.

Step by step guide

[T89 Preparation.]

E30M3SE said:

T89 Preparation. said:

VX Foxy said:

Could be a problem with the battery on the instrument pcb. Quite easy to replace.

Where abouts is this battery?

Soldered to the Si board.

Step by step guide

Thankypou sir

[VX Foxy]

That's the one

[T89 Preparation.]

T89 Preparation. said:

E30M3SE said:

T89 Preparation. said:

VX Foxy said:

Could be a problem with the battery on the instrument pcb. Quite easy to replace.

Where abouts is this battery?

Soldered to the Si board.

Step by step guide

Thankypou sir

Cheers guys,

I have just changed the battery and the Oil Service LED's have stopped going mental and the Temp Gauge is working again (the most important thing) but still the Tacho' doesn't work. Any more ideas?

[Oi_Oi_Savaloy]

I'd register on www.e30zone.net and type this problem into the Technical Help area. There's not a single problem with an e30 that's not been dealt with on that board.

Good luck fella.

[E30M3SE]

T89 Preparation. said:

T89 Preparation. said:

E30M3SE said:

T89 Preparation. said:

VX Foxy said:

Could be a problem with the battery on the instrument pcb. Quite easy to replace.

Where abouts is this battery?

Soldered to the Si board.

Step by step guide

Thankypou sir

Cheers guys,

I have just changed the battery and the Oil Service LED's have stopped going mental and the Temp Gauge is working again (the most important thing) but still the Tacho' doesn't work. Any more ideas?

While it was all apart did you inspect the Si board itself for defects in the tracks or cracks?

Input pin on the cluster is A7 (blue connector, black wire) also check connector C101 on the bulk head, engine loom as the signal to the tacho comes directly from the ECU black wire pin 9 on C101 connector.

These may help for reference.

[T89 Preparation.]

E30M3SE said:

T89 Preparation. said:

T89 Preparation. said:

E30M3SE said:

T89 Preparation. said:

VX Foxy said:

Could be a problem with the battery on the instrument pcb. Quite easy to replace.

Where abouts is this battery?

Soldered to the Si board.

Step by step guide

Thankypou sir

Cheers guys,

I have just changed the battery and the Oil Service LED's have stopped going mental and the Temp Gauge is working again (the most important thing) but still the Tacho' doesn't work. Any more ideas?

While it was all apart did you inspect the Si board itself for defects in the tracks or cracks?

Input pin on the cluster is A7 (blue connector, black wire) also check connector C101 on the bulk head, engine loom as the signal to the tacho comes directly from the ECU black wire pin 9 on C101 connector.

These may help for reference.

Cheers, I'll have another look at the Si board, it looked O.K if a little 'dry' so I will have a detailed check and make sure it is all good.