Check light and panel inoperative
Yo. I am new to the forum and to BMWs, and I just recently came into access of a 1986 BMW 325e - 'access' meaning that it's my roommate's car and that I get to drive and do whatever I want with it. As such, and coming from the worlds of Jeep and Mazda, I jumped all over this opportunity and have been working on it for the past couple of months.
One of the current issues I am facing is with the check light on the instrument cluster and the check panel above the rear-view mirror, neither of which are operating. First off, I recently replaced the old VDO instrument cluster (of which the only thing working on it was the gas gauge, and I came to find that this cluster had a corroded and swiss-cheese-holed SI board) for a Moto-Meter instrument cluster out of a 1987 BMW 325. I thought I would need to pull the SI board out of it and install it into the VDO cluster, as the back of the Moto-Meter cluster had a fourth green 'plug' or set of little plugs that was not a part of the VDOs set of yellow, white and blue plugs. However, I found out that this green plug cluster unclips on the sides and easily pulls out. It appears to work very similarly to how the SI board functions, using long metal pins to make contact with the mainboard. Having done this, I understand that there is a use for that cluster of plugs, but for what I have no idea.
With the green plug cluster now removed from the Moto-Meter, I installed the instrument cluster into my friend's 325e. Using only the yellow, white and blue plugs, everything appears to operate perfectly - I now have a working tach, speedo, temp. gauge, fuel gauge, and all lights except for the Check light. Neither it or the panel above the rear-view mirror are functioning. All appropriate fuses under the hood have been checked and I have combed through threads with the search tool before posting.
What is the next step to take? Is the new Moto-Meter cluster incompatible with the Check control system, or is the green plug cluster what operates the light and panel? If not, and just for curiosity's sake, does anyone know what the plugs operate?