400E Instrument panel warning lights not working on left side

[Black 034]

The left side warning lights are not coming on with key on engine off. The high beam works ok and right side are intermittent. I have changed bulbs, sockets and ohmed out the 15 pin connector on the board. Before I go looking for a used cluster I was wondering if I have the wires crossed in the 4 pin connector on lower harness behind CAN box. The alternator has a new regulator installed when harness was rebuilt and is charing 14.4 volts at idle. I was hoping to find a pinout of the four wires going into the connector and which pin on the 15 connector is the alternator sense wire.

Thanks for your help.

 

[gsxr]

It's unlikely your cluster has failed. The starter harness connector is X27.

Schematic for starter/alternator here:

https://www.500eboard.co/forums/misc/Manuals/Servicev3.2/W124/w124CD1/Program/ETM/2415200.pdf

Schematic for oil pressure/level sensors to the instrument cluster:

https://www.500eboard.co/forums/misc/Manuals/Servicev3.2/W124/w124CD1/Program/ETM/24544001.pdf

 

[Black 034]

Thanks I have those schematics, but not able to identify pin out of X27. I had pictures of the connector, but updated Iphone and they disappeared. I know the oil pressure is right because the gauge works so only ones that could be switched are oil level and field wire.

 

[Black 034]

The schematic does show it goes through light module and I have tried two light modules that have had the pins resoldered and tested as I had to repair no fog light or running lights on right side of car.

 

[gsxr]

X27 will have numbers on the plastic housing itself.

In this photo of the 034 connector, only one number is readable, next to the empty hole:

 

[natejgreene9871]

I’ve had grounding issues with MB instrument clusters before. May need a little soldering. I can’t remember if the warning lights are grounded via the pcb or if they have a dedicated ground wire to each bulb?

 

[Black 034]

Mystery solved on X27 connector alternator field wire in socket 5 instead of socket 4! Thanks for all the help everyone>

 

[gsxr]

Glad you got it sorted out!

Just to clarify - having the wires backwards at X27 caused all the warning lights on the left side of the cluster to not illuminate?

 

[Black 034]

That is correct because the field wire goes through X27 to light module and then to instrument cluster on pin 9. The other thing is the alternator worked just fine putting out 14 volts. I changed a lot of stuff at once, rebuilt lower harness, new regulator in alternator, instrument panel out to repair odometer, repaired light module due to no right side running lights and replaced all the fuses so figured I caused the issue just hard to track down.

 

[Black 034]

They weren't backwards the alternator field wire was in socket 5 instead of socket 4. Socket 5 is empty!