1986 190d Alternator Issues - PeachParts Mercedes-Benz Forum

Metafly · #1 03-13-2012, 11:19 PM

I am in the process of resurrecting a 190D.

My alternator was not charging the new battery. My alternator light was also on (along with the brake, oil and coolant lights dimly).

Today I removed the alternator and brought it in for testing/swapping. It tested slightly weak, so I replaced it with a new, rebuilt unit. The alternator is still not charging and the same lights are on as above. My sense is something is not wired right. The wires at the back of the alternator are clean and in good shape. I was sure to make the connections correctly.

I realize that sometimes new, rebuilt units are faulty, but is there something I can do to test the alternator and its circuit so I do not have to pull it it out right away for testing?

When I bought the car the two wires (found in post 1 here: http://www.peachparts.com/shopforum/diesel-discussion/313668-1986-190d-intro-no-start-etc.html)were disconnected from the X35 block near the battery. Connecting those gave me juice to the gp's. Could those two wires have something to do with my issue?

Thanks in advance for any thoughts or suggestions. Michael

ROLLGUY · #2 03-13-2012, 11:29 PM

Quote:

Originally Posted by Metafly

When I bought the car the two wires (found in post 1 here: http://www.peachparts.com/shopforum/diesel-discussion/313668-1986-190d-intro-no-start-etc.html)were disconnected from the X35 block near the battery. Connecting those gave me juice to the gp's. Could those two wires have something to do with my issue?

Thanks in advance for any thoughts or suggestions. Michael

I believe the large wire from the alternator to the battery is connected there. That could be where the problem lies.

Metafly · #3 03-13-2012, 11:35 PM

Quote:

Originally Posted by ROLLGUY

I believe the large wire from the alternator to the battery is connected there. That could be where the problem lies.

Thanks for the reply. Yes, the alternator does connect there. I am not sure how they go. There are four small wires going to the box with a phillips head screw. There are two other terminals with 10mm (head) bolts with two wires each (4). One is definitely in the alternator harness. One goes to the glow plug circuit. The other two go into the area behind the battery, where the relays/dash as far as I can tell.

I have wiring diagrams. Unfortunately, I suck at reading them.

ROLLGUY · #4 03-14-2012, 12:36 AM

I think the holes on the terminals are different sizes, and will only fit one way (big hole=big screw, small hole=small screw). The larger wires may be all +12v, and the smaller wires could be for the starter. Most wiring diagrams have a list of colors and wire gauges. It would be fairly easy to find the correct colors and wire gauge of the wires that connect onto the terminal block.