Tach swap problem

[DTFE30]

Last week I bought a mint vdo cluster from a 1988 325i to put in my 1985 325e because it has the higher red line on the tach for my S50 swap. When I plugged the new cluster in the tach did not werk. I have a euro cluster and had the same result. What needs to be done to get this to werk in my car?

[luckysnafu]

Does your 1985 325e cluster with the 5k tach work when hooked up to the s50?

[DTFE30]

Yeah. Everything werks. Even the fuel consumption guage.