Coding Plug Swap

[DTFE30]

I bought a cluster from a 1988 325i to put in my 1985 325e. I know I have to change the fuel gauge and the coding plug. The only problem is that the coding plug on the 88 is square and on the front and my 85 has a long stem coding plug on the back. What square coding plug do I need to make the 88 cluster work in my 85e? Should I just mount a VDO tach on my column like an old hot rod? I am doing this to accommodate my S50's higher rev limit btw..

[jlevie]

Both the 88 325i and the 85 325e have six cylinder engines. Which means that there is no reason to change the coding plug.

[DTFE30]

Why wont my tach work when I plug in the 88 cluster then?

[jlevie]

Could be any of a number of things like a bad SI board, bad tach, bad cluster, no tach signal, etc.

[DTFE30]

I have a euro cluster and the 88 cluster. both have the same result of no tach. My stock "e"cluster works fine.

[bmwm42]

you need a different coding plug while the e and the i are both 6 cyl they do have different r3v limits

[DTFE30]

Yeah What square coding plug do I need? My e cluster has a long pin for a coding plug, not a square one.

[bmwm42]

you cant use a early style coding plug on a late model cluster dude check out realoem.com to find the part number you need for it

[Varinn]

Or, you can try and find someone that would sell you their late cluster style eta coding plug

[DTFE30]

Is there a specific coding plug I need from an eta? are they all plug and play?

[jlevie]

I don't think this is a coding plug issue. The purpose of the coding plug is to tell the tachometer whether the engine has four or six cylinders. I haven't looked to see, but my suspicion is that wiring in your 85 doesn't match what the 88 (or later) cluster needs. You can go to http://wedophones.com/BMWManualsLead.htm, get the diagrams for your 85 and for an 88 and compare the pin outs of the cluster connectors.

[DTFE30]

Thanks! I will check it out.

[DTFE30]

I just checked and both clusters have the engine speed input as the black wire pin #7 on the c1 connector on the cluster.