I recently noticed the ScanGaugeII in my 2007 Sprinter was reporting a voltage below 12v. I had replaced the main battery within the last three weeks. So I connected my StarScan tool and confirmed the alternator output was 8.9v when I expected to see about 14v. I had read that these trucks are famous for the "y-cable" that connects the alternator, starter and battery. The cable runs transversely behind the oil pan and can easily be seen while looking from under the front of the truck.
The cable runs from the starter solenoid to the alternator. In this picture it is not easy to spot anything unusual.
This closer view shows the plastic convolute is not fully wrapping the cable. It is deformed from heat. The tape is also cracked from the heat.
This is the same cable as it runs behind the oil pan. In this picture, you can see the heat was enough to melt the convolute to the cable at the zip tie. The bulge in the cable at the left of the image is the inline fuse. The fuse is between the alternator and the starter solenoid lug. The starter solenoid lug is at the middle of the cable and the second leg of the y-cable runs to the battery tray under the driver's feet.
I called Bob at Hoekstra Transportation. They have the cable in stock and was quoted a price of $90.
This cable is reported to cause a great many engine codes. That may be because the battery voltage gets so low since the alternator is trying to charge the battery through a corroded cable.
I will post more pictures and notes when I remove and disassemble the cable.
The removed cable:
The end of the fuse close to the alternator got hot enough to deform the housing of the fuse.
It looks toasty. Why was the alternator putting out so much current?
The new cable: A 906 440 16 41
The cable did not fix any codes but I did notice that the battery voltage reported on OBD is more steady at 14.0 V +/-0.1 now.
Thanks a ton for that thorough writeup. It helped me greatly! I didn't know what to look for when people talked about the "y cable" in fixing my click start issue
ReplyDeleteinteresting to see. I have the same issue and will be replacing the cable with a custom one from alternator to battery direct. The ends will be crimped , soldered and sealed . this is the only way to prevent failure over time as water ingress will corrode the copper. the reason it got so hot as in the pictures is high resistance. the alternator was running at 14.2V the drop in these joints was dissipating huge amounts of power.
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