Slighty abstract request here, but does anyone have a picture of an e28 instrument cluster coding plug please? Or even better, a picture of the frequency-voltage converter which lives inside the plastic housing.
Not sure if this is what you are after but I have here a 528i Instrument cluster which show the connections etc, if you need pics of the vehicle connectors post in reply as the vehicle is still available, should you require I can remove the clocks from the face but need to know what you are looking for.
Cheers
Fishy
The Following User Says Thank You to fishy For This Useful Post:
Hi Fishy, thanks very much for the reply. The part I'm interested in is the black coding plug on the bottom left of the cluster as you look at it from the rear. What would be incredibly kind and helpful of you is if you could pull the plug out and then open it up and see if it has the same type of black chip (which is the voltage frequency converter) as shown in this picture:
This must all sound rather pointless, so I'll explain why I'm interested. Basically I want my 0-8000rpm tacho in my e30 m3 to work accurately with the s38 6 cylinder engine. As the M3 was a four cylinder car, the signal is all wrong with a 6 cylinder engine. I can swap the coding plug for an e30 6 cylinder version easily enough, but these only have a 0-7000 rpm scale - so isn't accurate with the m3 tacho.
I noticed that the e28 m5 uses a 0-8000 rpm tacho and of course this car has a six cylinder engine. What I was hoping is that I can get an e28 m5 coding plug, remove the voltage-frequencey converter, and fit it in place of the voltage-frequency converter in an e30 coding plug.
That chip wont be any use to me, but it has confirmed that the e28 uses the same components as the e30, so the M5 part should work a treat for my application.
Thanks alot for your help, I really do appreciate it.
just wondering how you got on with this issue ? What exactly does the coding plug do anyway, does it simply ensure that the tacho reads the correct value ?
I got an e28 m5 coding plug and pulled the housing off, then just plugged the chip into the M3 cluster and it works accurately which is most satisfying.
The coding plug takes care of the RPM signal and on non-//M cars also does the econometer. It will also influence the service lights as these take data from the rev counter (ie. the harder you drive the sooner they come on)
This is interesting to me as i'm contemplating an engine conversion however not with a 4 cyl M3. I'm in the middle of converting my 89 635 from auto to manual & once this is done the next step may be to install the s38 motor from the donor car.
Although both cars are 6 cyl, if i leave the std tacho in the car as you point out the upper rev limit is different (7 vs 8k) & i also thought the idle level wouldn't show accurately.
I could swap the whole instrument cluster but as the donor car is LHD, the speedo is in KMs etc. I thought that i could swap out the faces on the tachos (which will hide the econometer nicely) but this would leave me with an inaccurate reading, hence i'm wondering if the coding plug is the answer.
I see. I've just looked on the parts website to see how expensive a new 8000rpm e24/e28 tachometer is; about £300 which is a tad steep! I was going to suggest buying one of these in conjunction with the coding plug I used but that's quite a costly solution.
Actually, I've just re-read your post. Do you already have an e28 donor car for the engine? If so just take the cluster apart and transfer the tachometer from the M5 into the e24 instrument cluster. The e28 m5 and e24 m635 use the same tachometer so it should just slot straight in.
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