190E Windscreen washer pump

[JDUB]

My windscreen washer pump stopped working on my 1990 190E 2.6. The pump works if I jump direct battery juice to it. so its not the pump, So it is in the wiring, relay or switch. The wiring is buried and I don't have a clue where the relay is located. Any suggestions in my approach to this problem would be appreciated.

[mbdoc]

The largest relay in the fuse box is the combination relay & operates the pump. Check to see if this relay(module) clicks when operating the switch.

[JSlabotsky]

I have the same issue but on a 1990 300 CE - The pump is good, but not getting juice. How is the troubleshooting different on this model?

Thanks!

[JDUB]

I first tested the pump by directing two jumper wires from the battery to see if the pump motor would work. I next tried jumping the terminal with the brown wire to ground while someone operated the switch, and the pump would not operate. I tested for voltage at the violet wire with the yellow stripe when the switch was operated. No voltage was observed. I went and bought a new relay and it still would not work but I got power to the violet wire with the yellow stripe. I jumped a groung to the brown wire to the battery and it finally was fixed. The brown wire had high resistance and may have helped the fry the relay.

[JSlabotsky]

Can anyone comment on whether the circuit is similar in the 124 chassis? (1990 300CE in this case) I need to troubleshoot mine this week and, like I said, the motor turns when connected to 12v, but no power at the connector.

[mbdoc]

The W124 chassis has the same system as the W201(190) chassis. The combination relay is the second largest relay in the REAR section of the fuse box.