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A folks need some more help. I posted before that I have a low coolant light on my 2001 ML 320 that I cant turn off. I purchased a new coolant reservoir with cap and sensor but the light is still on. I noticed my coolant recirculation pump is inoperative and my E-box fan as well. I have received allot of great advice on this site hoping you guys can come through again. Does anyone have a wiring diagram for the ML series I'm really stumped of this one.
OK, the Coolant Level Sw. is a two wire Org. & Grn which runs from the reservoir to connector X18/10 which lives either on the side of the fuse box or under the fuse/relay module.
You must first find this conn., disconnect it and conduct a separate continuity test with a DVOM for each wire from the disconnected connector at the reservoir to the X18/10 connector.
If there is no break in the wires, then you must conduct the same test from the X18/10 conn. to conn. "B", wire numbers 7 & 8,on the Instrument Cluster.
To remove the fuse/relay module, remove both covers to the fuse box, then three additional screws and pull the module up and out of the fuse box. Turn it over and lay it on a folded towel.
Ok Maj so I lift the fuse box and underneath I will find the connector and make sure I have continuity to the plug at the reservoir? If that's ok do I have to pull the instrument cluster to get to the other con "B" 7&8 ?
Ok Maj so I lift the fuse box and underneath I will find the connector and make sure I have continuity to the plug at the reservoir? If that's ok do I have to pull the instrument cluster to get to the other con "B" 7&8 ?
In the fuse box you will find many connectors. You have to find a connector with just two wires, Orange and Green.
Yes you will have to remove the Instrument Cluster. Refer to this link to remove the cluster. Tilt the steering wheel to its lowest position and remove the cluster. There is no need to remove the steering wheel.
The Coolant Level Sw. does not work as a normally open or closed system. It has two electrodes in the tank which reads the amount of fluid in the reservoir and sends an Ohm signal to the Instrument Cluster.
If there is enough fluid, the Ohm value is read by the I.C. and does not illuminate the light. Conversely, if the fluid gets low it sends a different Ohm value to the I.C. and triggers the light.
I have an opposite issue with my 2nd/3rd hand 98 ML320. Seems that the overflow reservoir was changed out (found in a recycle yard by some tell tail markings I found) and possibly the MFG switched up designs mid stream on the connector. While pulling the tank to clean it I found the connector not plugged in. Upon re-installation, I found that the connector from the firewall does not fit the mate on the tank. Turning the keyswitch to KOEO the low coolant lamp functions but after starting the vehicle it turns off as it is receiving a signal from the sensor even though the sensor is not plugged in. I checked the firewall connector and have power on one pin, nothing on the other. Did a ohm check for a short, nothing there. Its got me baffled as well as others.
Sir - As you stated, the wires are orange and green. I do not have a blue wire. Regarding the connector not mating, the connector from the firewall should slip over the mating connector on the tank. They physically don't fit. See attached images.
As you suspected, I also suspected that somewhere along the line the connector was changed but I don't believe that was the case as the terminations to the connector appear to be factory. As per your request the VIN is as follows.
Here's the problem. The last 6 numbers of your vin# is 00820.
For the first 051463 MLs they had one Expansion Tank and every W163 ML produced after that had a different tank.
So the previous owner needed to change the tank, for whatever reason, and did so with the newer version, because the older version was not available any longer.
That means that you have a new tank with an old connector. So what you have to do is purchase a new type connector from M/B and remove the wires from the old conn. and switch them to the new one.
The conn. you need is 003 545 31 26.
I suggest you carefully cut away the plastic without damaging the metal pins and you will be good to go.
Thank you for the investigation work. That is what I did suspect in the first place, i.e. mfg switch up in early/mid year. Sad part about is that I'll be hard pressed to find that connector 18 years later. I'll keep looking.
I forgot to mention that this still does not answer the mystery of why the lamp illuminates on KOEO but yet goes out upon engine start. The sensor is disconnected. Possibly due to the capacitve feedback or lack thereof from the tank probes? I suppose I can run an adapter connection cable and try that.
Thank you for the investigation work. That is what I did suspect in the first place, i.e. mfg switch up in early/mid year. Sad part about is that I'll be hard pressed to find that connector 18 years later. I'll keep looking.
Regards.
- rev -
The only thing you have to do is go to any M/B dealer and order the part number I supplied you. What's so hard about that?
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