Rev counter and ecomometer not working

[Scoot1]

Hi everyone,

I went to Prescott Hill climb at the w/e put the hood down and whilst driving merrily along I noticed the rev counter and econometer are not working.
Any help as to what i should do, be looking at to fix this please.

Thanks

[Blitz]

Its probably a fuse. Check for blown fuses in the fuse box.

[Scoot1]

Thanks will do, would the economenter may be vacuum related in any way?

[Grrrmachine]

Before BrianMooore swears at you, no, BMW don't use vacuum-driven lines. They get their feed from the ECU.

I have found mine to be a bit tempremental at times and this is because of dirty pins on one of the engine loom connectors (on an M20 engine, it's the one that's affixed to the firewall just behind the inlet manifold.) Taking that apart, cleaning pins and sockets with contact cleaner and replugging it solved the issue.

[Scoot1]

Thanks, Brief update I took the day off yesterday as it was my other halfs Birthday, she was not too pleased when she tracked me down to the garage with my head under the bonnet pulling fuses out of the cabbie, esp as she was ready to go out for the day (cost me a trip to the shops).

Suffice to say all fuses are in tact, so thanks Grrmachine I will clean the pins on the loom and see what happens.

Apologies to all in lieu of making reference to vacuum's.

[Green]

I have the same issue with my m20, I think it could be down to the SI board's batteries being dead which means having to remove the clocks and soldering in new batteries for it.
Can't say for sure though. Also been told it could be the sender on the diff?

[Cabri-Ole]

Had same prob on my 325i. Was the SI board. Bought a replacement board with batteries already soldered in. Now works fine. Leaky batteries damage the SI board.

[lawriejones]

Excuse me for my ignorance.
What are si boards and batteries, as i'm having a similar problem, my speedo isnt working but my rev counter is.

[Cabri-Ole]

SI = Service indicators ie your little red, yellow and green led's on the instrument panel. Inside the instrument cluster is a circuit board that among other things keeps a tab on the cars service and has batteries to power this, in case you should disconnect the main car battery. Eventually these little blighters corrode and leak all over the circuit board causing gauges on the instrument panel to die or behave erratically!

[_bmw_316_lad_]

iv replaced my si board and batteries and working fine but just went dead again a month ago. the si board was only replaced a year ago

[Saga]

Excuse me for my ignorance.
What are si boards and batteries, as i'm having a similar problem, my speedo isnt working but my rev counter is.

Check the diff sender if you haven't - very easy. Look at diff - is the plug still in place/wires in good condition?

[Scoot1]

Hi everyone

Thanks for the advice will embark upon sorting the problem in the morning starting with the easy fixes such as cleaning the terminals, diff sender.

If the diff sender is not connected properly does that mean the speedometer and odometer will not work?

The speedometer and odometer are working on mine currently but the rev counter and econometer are not. So is that related to the diff sender?

[daimlerman]

Hi everyone

Thanks for the advice will embark upon sorting the problem in the morning starting with the easy fixes such as cleaning the terminals, diff sender.

If the diff sender is not connected properly does that mean the speedometer and odometer will not work?

The speedometer and odometer are working on mine currently but the rev counter and econometer are not. So is that related to the diff sender?

Unlikely.
Most rev counter/ecometer problems are traced to the SI board having leaky batteries.
Cheap fix is a s/h cluster,you can always swap in your current speedo if the milage showing is an issue.

[lawriejones]

Thanks Saga.
I tried a new sensor and checked the wiring. Ive got continuity to the sensor from the plug under the passenger seat. Will need to check continuity from cluster to plug now. Hopefully if this is ok, i'm probably looking at a new cluster I would think/hope.

Any other ideas will be appreciated.

[Green]

Could someone point me in the right direction of the right batteries to buy for the SI board and where i can purchase them from? Rather sort it out pre-taking the clocks out.