These issues seemed to all happen at the same time when I had my dash out.
1) The left side of my instrument cluster is dead. The coolant temp gauge, oil pressure, and fuel level, as well as all warning lights on that side except for the battery light and high beam indicator. Also all the illumination lights aren't working.
2) When starting the engine, the battery light and abs light remain on, when I tested at the alternator I was only at 12.5v with the engine running. However, when I give it gas (say 2000 rpm just once) the battery light goes off and the alternator voltage is goes up to normal output of 14.5v and will be fine. Issue is only when first cranking the engine, the minute i blip the throttle to about 2000 rpm, everything is fine.

I have checked all fuses, even the small red circuit board fuse on the back of the cluster and all is fine. The alternator is literally brand new with maybe a couple hundred miles on it. I want to say it sounds like a bad ground somewhere, but they all seem fine, I even redid some of the ring terminals that looked a little suspicious.

One test I did do was KOEO and unplugged the oil pressure sender. That would usually cause the oil pressure gauge to peg at 3 bars, but when I did it, I got nothing. I even checked for continuity between the sender plug and ground and all checked out fine so I know the sender is good. Also I know the cluster functions that are currently not working are ok because I bench test the needles and lights and got them all to function. So what is going on? Is this all related? Where is the cluster grounded at on the left side? and what about the battery light coming on??

__________________

1990 190E 3.0L

The cluster portion has been resolved.

__________________

1990 190E 3.0L

What was the fix?

Duke

I'm not 100% sure, but I just replaced the circuit board P/N A2015423001. There was some component that failed on my old one and I didn't wanna spend too much time trying to figure that out when I have the other on-going issues. So now all the gauges work again, but the illumination of the backlights on the center console and cluster itself are still out and also the charging issue remains. I have plenty of the red circuit board fuses on the back of the cluster and it isn't that for the illumination so now I'm just tracing wires. Adding +12v to the X6 where the gy/bu wires all join up turns on the lights. Also adding +12v to the 4 pin connector on the back of the cluster turns on the lights as well. I see that terminal 58d is what controls the illumination, but for whatever reason, my w201 seems to be the 1-off model because though I do have some of the same wiring as what the FSM shows, a lot of it is not and so I toggle between the w201 and w124 FSM and try to figure it out.

__________________

1990 190E 3.0L