craft1

I am not one to have the vehicle tooken to the dealer for something small, but this seems to be a bit of a problem here. So I am asking for some help.

My moms friend has a 2000 model CL500 and yesterday morning she called my mom to ask her if I would come look at her call cause the coolant light was on. So I went over and her car has the message on the cluster that says "Coolant Visit Workshop". Well assuming the level is low, I check the resovoir and the level is at the top of the container. Well now I am assuming there is an issue with the coolant level sensor.

Well after talking with my friend at the mercedes dealer (he isnt that experienced with mercedes since he hasnt worked there very long and he did however tell me that the coolant level sensor is in series with the washer fluid level sensor. and if either is faulty it can trigger the other one. he also gave me some specs from netstar for the resistance on both switches. both have a resistance of less then 5 ohms with a low fluid reading and 110 for a full reading for the coolant sensor and 160 for the washer level sensor.

Well armed with that info I decided to first test the washer level switch/sensor. now I found that the sensor is magnet operated and with it closed (fluid full position) I had 0.0 ohms and open I had 170 ohms. immediately I assumed the switch was faulty since the readings were opposite. and since 0.0 ohms means something is wrong. friend said it is most likely shorted. Well I went a purchased a new switch from the dealer which had to order it since it wasnt in stock and we got it in today. Well I picked it up and after I installed in, the message was still displaying "coolant, visit workshop". well I pulled off that switch and measured it and I got the same readings, only this time I got 0.4 ohms with it closed and again 170 ohms with it open. now I have a feeling that the specs on netstar may be wrong. So I went and checked the reading of the coolant level sensor with the coolant in the resovoir and it read 110 ohms with the coolant full. which is in spec.

Now just to check to see if maybe this was a wiring issue, I disconnected the coolant sensor and looked at the cluster and it said this time, coolant level low. and also coolant, visit workshop. plugged it back in and the low level went away, but the other message stayed. I then unplugged the washer fluid level switch and the cluster said washer fluid level low and coolant vist workshop. plugged it in and only the coolant visit workshop remained.

So I am stumped at this point. it seems like the wiring is fine since the cluster reconizes that the switches are connected and what not. My friend said the info went through the front SAM and I assume from there is is sent on the interior can bus to the cluster.

Now is it possible that there is a CAN issue here? or possibly a faulty SAM or faulty Cluster or just maybe one or the other needs to be flashed? not sure how else to check this issue, if anyone has an idea, please let me know?

Also would this issue bring up any codes through SDS?

craft1

well I fixed the problem. stupid me, I went into the owners manaul and checked for any info about that message and sure enough found info on "coolant Visit Workshop". it said that if that light is on, the cooling fan is faulty. or a problem with it.

So I had my friend at the dealership hook up the SDS to the vehicle this morning and sure enough there was a stored fault in the ME-SFI control module for the suction fan. since it was stored, he cleared it and the message went away.