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I am way out of my depth on this one. Any help or advise is appreciated. Vehicle is a 2001 ML320 (wfiey's car)
Issue: W163.154 No air conditioning - 1) compressor fails to engage 2) aux fans fail to engage.
With my YouCanic Scan Tool I attempted to manually engage the compressor, but the tool failed to establish communications with the module responsilbe for air conditioning functions.
I performed a full system scan, and everything passes with the exception of EAM and EAA having numerous CAN bus faults in each.
Diagnostics:
From the look of things it appears as though I have a CAN bus connection issue that prevents the EAM and AAM modules communicating to the devices they need to communicate with.
History: Earlier this year I replaced the brake master cylinder. That repair required me to raise the fuse panel wiring located immediately behind the fuse block so that I could better access the master cylinder. I may have loosened a connection in the process. Which one, however, remains to be discovered.
I consulted Xentry for the CAN Bus Wiring Diagram for my ML320 (see below)
The EAM is denoted N10/1 and the AAM is denoted N10 in the wiring diagram. It appears to me the EAM is connected to the bus via the AAM. My thoughts are that I must have dislodged a wire leading to the AAM and the -
Interior Connector sleeve Z51/3 on the CAN high 2 side (ws wire) or Z51/4 on the CAN low 2 side (gn wire) or
Interior Connection sleeve Z51/1 on the CAN high 1 side or Z51/2 on the CAN low 1 side.
Questions: How do I test the CAN Bus connections with my Hand Held Meter? I don't have an oscilliscope. What are the .35 and .5 appearing in the diagram representative of (ohms, amps)? I have read that the EAM is under the passenger side footwell, but the wiring diagram shows it attached to the AAM? Am I right to think they are located next to each other in the engine bay behind the fuse panel? If in fact the EAM is in the passenger footwell, then I am wondering if water incursion could have played a part in this drama via the sunroof drain tube. In any event I will be removing the fender and affixing a proper drain to eliminate any issue relatting to water entering the car in the future.
If you have Xentry you should have "Star Finder". Enter the module identifier for your model and it will bring up a photo of the location. Alternatively, go into WIS for replacing/troubleshooting the module of interest and, again, there will be photos of the location and instructions on removal/replacement.
If you have Xentry you should have "Star Finder". Enter the module identifier for your model and it will bring up a photo of the location. Alternatively, go into WIS for replacing/troubleshooting the module of interest and, again, there will be photos of the location and instructions on removal/replacement.
Well I'll be! I cleaned the battery terminals Started the car, cleared the codes and now I can talk to the EAM and AAM.
What is puzzling is when I cleared the codes before cleaning the terminals, the codes came back. After cleaning the terminals and clearing the codes, I am able to access both the AAM and EAM. As well I can get look at the A/C functions. I suppose the reason the compressor is not kicking in is because the coolant pressure is to low in the system. For the ambient temp shown it should be about 40 - 50 psi and it currently shows 21 psi.
Today, 02:58 PM
