Hi I am new to this forum but could bot find any reference to my problem.

​​​​​I purchased a second hand sport instrument cluster to replace my ugly standard speedometer (with no tacho). Anyway it worked fine but it has only 1 connector while my original one has 2. If I connect only 1 the cluster works perfectly but I noticed that the ac and rear window heater does not work. I think the second connector controls them. Does anyone has some more information please? Or maybe some cluster wiring diagrams or pinouts would be great. Thanks for your help